Tag Archives: milky

New Research Unveils Milky Way’s Central Black Hole as a Compact Object of Fermion Dark Matter

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For decades, the movement of stars near the center of our Milky Way galaxy has provided some of the most convincing evidence for the existence of a supermassive black hole. However, Dr. Valentina Crespi from the La Plata Institute of Astrophysics and her colleagues propose an innovative alternative: a compact object composed of self-gravitating fermion dark matter, which could equally explain the observed stellar motions.

A compact object made of self-gravitating fermion dark matter. Image credit: Gemini AI.

The prevailing theory attributes the observational orbits of a group of stars, known as the S stars, to Sagittarius A*, the supposed supermassive black hole at our galaxy’s center, which causes these stars to move at speeds of thousands of kilometers per second.

In a groundbreaking study, Dr. Crespi and her team propose that fermions—a specific type of dark matter made from light elementary particles—can form a distinct cosmic structure that aligns with our current understanding of the Milky Way’s core.

The hypothesis suggests the formation of an ultra-dense core surrounded by a vast, diffuse halo, functioning as a unified structure.

This dense core could replicate the gravitational effects of a black hole, thereby accounting for the orbits of S stars and nearby dusty objects known as G sources.

A vital aspect of this research includes recent data from ESA’s Gaia DR3 mission, which meticulously maps the Milky Way’s outer halo and reveals the orbital patterns of stars and gas far from the center.

The mission has documented a slowdown in the galaxy’s rotation curve, known as Keplerian decay, which can be reconciled with the outer halo of the dark matter model when combined with the standard disk and bulge components of normal matter.

This finding emphasizes significant structural differences, bolstering the validity of the fermion model.

While traditional cold dark matter halos spread in a “power law” fashion, the fermion model predicts a more compact halo structure with a tighter tail.

“This research marks the first instance where a dark matter model effectively connects vastly different scales and explains the orbits of various cosmic bodies, including contemporary rotation curves and central star data,” remarked Carlos Arguelles of the La Plata Astrophysics Institute.

“We are not merely substituting black holes for dark objects. Instead, we propose that supermassive centers and galactic dark matter halos represent two manifestations of a single continuum of matter.”

Importantly, the team’s fermion dark matter model has already undergone rigorous testing.

A recent 2024 survey demonstrated that as the accretion disk illuminates these dense dark matter cores, it produces shadow-like features reminiscent of those captured by the Event Horizon Telescope (EHT) collaboration at Sagittarius A*.

“This point is crucial. Our model not only elucidates stellar orbits and galactic rotation but also aligns with the famous ‘black hole shadow’ image,” stated Crespi.

“A dense dark matter core bends light to such an extent that it forms a central darkness encircled by a bright ring, creating an effect similar to shadows.”

Astronomers performed a statistical comparison of the fermion dark matter model against traditional black hole models.

While current data on internal stars cannot definitively distinguish between the two theories, the dark matter model offers a cohesive framework to elucidate both the galaxy’s center (encompassing the central star and shadow) and the galaxy at large.

“Gathering more precise data from instruments like the GRAVITY interferometer aboard ESO’s Very Large Telescope in Chile, and searching for specific features of the photon ring, an essential characteristic of black holes that are absent in the dark matter nuclear scenario, will be crucial for testing the predictions of this innovative model,” the authors noted.

“The results of these discoveries have the potential to revolutionize our understanding of the fundamental nature of the Milky Way’s enigmatic core.”

The team’s research was published today in Royal Astronomical Society Monthly Notices.

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V. Crespi et al. 2026. Dynamics of S stars and G sources orbiting supermassive compact objects made of fermion dark matter. MNRAS 546 (1): staf1854; doi: 10.1093/mnras/staf1854

Source: www.sci.news

Mysterious Glow Around the Milky Way May Provide First Evidence of Dark Matter

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For nearly a century, dark matter has posed a significant enigma. Although it outnumbers ordinary matter by a ratio of five to one, it remains invisible and undetectable by current technology.

A daring new analysis of 15 years of data from NASA’s Fermi Gamma-ray Space Telescope now claims to shed light on this mystery.

The latest research reveals the detection of a peculiar halo-like glow of gamma rays surrounding the Milky Way galaxy, with distinct peaks in energy that align closely with the signals predicted for a specific type of hypothetical dark matter particle.

These particles, referred to as weakly interacting massive particles (WIMPs), can generate gamma rays by annihilating one another.

“If this is validated, it would be the first instance where humanity has ‘seen’ dark matter,” stated Professor Tomonori Toya, an astronomer at the University of Tokyo and co-author of the study.

In an interview with BBC Science Focus, he expressed his initial skepticism: “When I first noticed what looked like a traffic light, I was doubtful, but after careful investigation, I became convinced it was accurate—it was an exhilarating moment,” he shared.

However, despite the excitement surrounding the new signals, independent experts caution that this discovery is far from conclusive.

This possible breakthrough emerges nearly a century after Swiss astronomer Fritz Zwicky first proposed dark matter’s existence, after observing that the galaxies in the Milky Way cluster were moving too swiftly for their visible mass.

Mr. Toya’s study, published in the Journal of Cosmology and Astroparticle Physics, scrutinized 15 years of data from the Fermi telescope, focusing on the regions above and below the Milky Way’s main disk—known as the galactic halo.

After modeling and accounting for known sources of gamma rays, such as interstellar gas interactions, cosmic rays, and massive bubbles of high-energy plasma at the galaxy’s center, he identified a leftover component that shouldn’t exist.

“We detected gamma rays with a photon energy measuring 20 giga-electron volts (or an impressive 20 billion electron volts), extending in a halo-like formation toward the Milky Way’s center,” Toya explained. “This gamma-ray-emitting component aligns with the expected shape of a dark matter halo.”

A gigaelectronvolt (GeV) represents a unit of energy utilized by physicists to quantify subatomic particles’ energy levels—approximately a billion times the energy that a single electron attains when traversing a 1-volt battery.

The potential dark matter signal identified by Toya sharply rises from a few GeV, peaks around 20 GeV, and subsequently declines, consistent with predictions for WIMPs, which possess about 500 times the mass of a proton.

This gamma-ray intensity map illustrates a signal that may originate from dark matter encircling the Milky Way halo. The gray horizontal bar in the central area represents the galactic plane, which was exempted from the analysis to avoid strong astrophysical radiation. – Photo credit: Tomonori Toya, University of Tokyo

In Totani’s perspective, this data significantly indicates the existence of dark matter. “This marks a crucial advancement in astronomy and physics,” he asserts.

Nevertheless, Jan Conrad, a professor of astroparticle physics at Stockholm University in Sweden and an independent expert in gamma-ray searches for dark matter, advises prudence.

“Making claims based on Fermi data is notoriously challenging,” he remarked to BBC Science Focus.

This isn’t the first instance of astronomers witnessing such phenomena; the story stretches back to 2009, shortly after the Fermi telescope’s launch. In that year, researchers identified an unexplained surplus of gamma rays emanating from the galactic center.

For years, this finding stood out as a compelling hint of dark matter. However, Conrad pointed out that even after 16 years, the scientific community has yet to arrive at a consensus about the signal’s dark matter roots.

“It’s believed to be related to dark matter,” he claims. “Despite accumulating data and enhanced methods since then, the question of dark matter’s existence remains unresolved.”

Even at this juncture, researchers who have spent over a decade working to disprove the galactic center excess are unable to definitively prove it is astrophysical in nature (originating from sources other than dark matter), nor can they confirm it is attributable to dark matter. The issue remains unsolved.

Conrad emphasized that the emerging signals from the halo are insufficiently studied and will likely necessitate many more years of investigation for verification. Both the new halo anomaly and the much-debated galactic center signal share a common challenge: noise interference.

In these regions, gamma rays potentially stemming from dark matter annihilation may also originate from numerous other, poorly understood sources—complicating efforts to reach definitive conclusions.

“The uncertainties surrounding astrophysical sources make it exceedingly difficult to assert strong claims,” Conrad stated.

Despite their differing confidence levels, both Totani and Conrad highlight the same forthcoming focus: dwarf galaxies.

These small, faint galaxies orbiting the Milky Way are believed to contain significant amounts of dark matter while exhibiting minimal astrophysical gamma-ray background, rendering them ideal for studying dark matter annihilation.

“If we detect a similar excess in dwarf galaxies, that would provide compelling evidence,” Conrad said. “Dwarf galaxies provide a much cleaner environment, allowing for potential confirmation.”

Dr. Toya concurred, noting, “If the results of this study are validated, it wouldn’t be surprising to observe gamma rays emitting from dwarf galaxies.”

The Cherenkov Telescope Array Observatory (CTAO) is the most sensitive ground-based gamma-ray observatory ever constructed, offering a powerful new approach to scrutinize whether this enigmatic signal is indeed dark matter. – Photo credit: Getty

Yet, the ultimate verification of Toya’s discovery might be closer to home. Experiments designed to detect dark matter are currently taking place in facilities situated deep underground around the world.

“If we were to observe a signal there that aligns with a WIMP of the same mass…that would present a robust argument, as it would be much cleaner,” Conrad pointed out.

In the coming years, the next-generation Cherenkov Telescope Array Observatory (CTAO) will significantly enhance sensitivity to high-energy gamma rays, enabling researchers to analyze halo signals with greater detail.

“Naturally, if this turns out to be true, it’s a significant discovery,” Conrad said. “The true nature of dark matter remains elusive. A clear signal indicating dark matter particles would be monumental. However, further research is essential to explore alternative explanations for this excess.”

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Source: www.sciencefocus.com

Study Reveals Disappearance of Dark Matter as Cause for Excess Galactic Centers in the Milky Way

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The galactic center excess refers to an unexpected intensity of gamma rays emerging from the core of the Milky Way galaxy.

This view displays the entire sky at energies exceeding 1 GeV, derived from five years of data from the LAT instrument on NASA’s Fermi Gamma-ray Space Telescope. The most striking aspect is a luminous band of diffuse light along the center of the map, indicating the central plane of the Milky Way galaxy. Image credit: NASA/DOE/Fermi LAT collaboration.

Gamma rays are a form of electromagnetic radiation characterized by the shortest wavelengths and the highest energy.

The intriguing gamma-ray signal from the Milky Way’s center was initially observed in 2009 by the Large Area Telescope, the primary instrument of NASA’s Fermi Gamma-ray Space Telescope.

The source of this signal remains under discussion, with main hypotheses involving self-annihilating dark matter and undetected populations of millisecond pulsars.

“When Fermi directed its gaze toward the galaxy’s center, the outcome was unexpected,” remarked Dr. Noam Libeskind, an astrophysicist at the Leibniz Institute for Astrophysics in Potsdam.

“The telescope detected an excessive number of gamma rays, the most energetic form of light in the universe.”

“Astronomers worldwide were baffled, and numerous competing theories emerged to clarify the so-called gamma-ray excess.”

“After extensive discussion, two primary theories surfaced: either these gamma rays stem from millisecond pulsars (highly dense neutron stars rotating thousands of times per second) or from dark matter particles colliding and annihilating. Both theories, however, have their limitations.”

“Nonetheless, our findings strongly support the notion that the gamma-ray excess arises from dark matter annihilation.”

In their study, Dr. Libeskind and his team simulated the formation of the Milky Way galaxy under conditions akin to those in Earth’s neighboring universe.

They discovered that dark matter does not radiate outward from the galaxy’s core but is organized similarly to stars, suggesting that it could also contribute to the excess gamma rays.

“The Milky Way has long been recognized as existing within a spherical region filled with dark matter, often referred to as a dark matter halo,” explained Dr. Mourits Mikkel Mur, an astrophysicist at the Potsdam Leibniz Institute for Astrophysics and the University of Tartu.

“However, the degree to which this halo is aspheric or ellipsoidal remains unclear.”

“We analyzed simulations of the Milky Way and its dark matter halo and found that the flattening of this region sufficiently accounts for the gamma-ray excess due to self-annihilation of dark matter particles.”

“These calculations indicate that the search for dark matter particles capable of self-annihilation should be emphasized, bringing us closer to uncovering the enigmatic properties of these particles.”

A study of the survey results was published in this month’s edition of Physical Review Letters.

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Mikel Mur the Moor et al. 2025. Excess forms of dark matter in Fermi LAT galactic center Milky Way simulations. Physics. Pastore Rhett 135, 161005; doi: 10.1103/g9qz-h8wd

Source: www.sci.news

The Perfect Season to Admire the Milky Way

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Milky Way over Uluru, Australia

Stefan Liebermann/Mauritius Images GmbH/Alamy

Being located in the Northern Hemisphere, my recommendations for observing the night sky are often limited by this perspective. Thus, in this edition, we shift our focus to the stunning views offered by the Southern Hemisphere, particularly the Milky Way during this time.

Every visible star belongs to our galaxy; when I gaze at the night sky, I’m encountering the Milky Way. Stargazers refer to the Milky Way as the luminous bands of stars and cosmic dust found toward the core of our spiral galaxy. This plane is tilted approximately 60 degrees relative to the solar system, enabling us to see the inner edge of the spiral arm that faces away from our location. Viewed in three dimensions, it resembles a curved arc across the sky.

This view is significantly enhanced in the Southern Hemisphere due to the Earth’s tilt. Stargazers in the southern part of the globe have the advantage of looking toward the galaxy’s center, while those in the north gaze away from it into a star-bereft region. This positioning allows for a clearer view of numerous constellations near the galactic core, including Centaurus and Sagittarius.

Regardless of your location on Earth, we share the same sunlit side, making this the optimum time for celestial observation. However, the Southern Hemisphere offers year-round visibility of the Milky Way—a perk of our planet’s tilt plus the benefits of darker nights during this season.

A decade-old study indicates that one-third of the global population is unable to see the Milky Way, a figure likely increasing due to growing light pollution. I encourage you to seek a remote location on a moonlit night; a new moon, around June 25th, would be ideal. It typically takes your eyes about 40 minutes to adjust to darkness, so if you’re in the Northern Hemisphere, you might need to wait until after midnight for optimal conditions.

Some of my most unforgettable nights under the stars occurred in the Southern Hemisphere. The first was at Mount Cook, New Zealand, in early June, and the second was at Warrumbungle National Park, Australia, in April. On both occasions, I was utterly amazed by the sight of the Milky Way, as captured in the image of Uluru, Australia.

If you’re stargazing in the Southern Hemisphere, make sure to look for the Milky Way. You might even spot two of our neighboring galaxies: the Large and Small Magellanic Clouds. Neither of these is visible from the Northern Hemisphere but can be located near the southern celestial pole.

Abigail Beall is the editor of New Scientist and author of Art of Urban Astronomy. Follow her @abbybeall

For additional projects, visit newscientist.com/maker

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Source: www.newscientist.com

Milky Way Black Holes Could Be Rotating at Their Limit

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SEI 255742397

Image of Sagittarius A*, the black hole at the center of the Milky Way galaxy

EHT

At the core of our Galaxy lies an extraordinary rotating entity: a black hole that appears to be spinning near its maximum velocity.

Michael Jansen from Radboud University in the Netherlands and his team investigated black holes in the center of the Milky Way, specifically Sagittarius A*, utilizing data gathered by a collective network known as the Event Horizon Telescope (EHT). To tackle the intricacies of the data, they opted for artificial intelligence methods.

Initially, they simulated approximately one million black holes using established mathematical models, a computational endeavor that necessitated millions of hours on supercomputers. These simulations served as training data for a type of AI known as neural networks, enabling them to assess the properties of black holes based on empirical observations. Subsequently, they fed the AI with data on Sagittarius A* collected by the EHT throughout 2017.

The AI determined that Sagittarius A* is rotating at 80-90% of its theoretical maximum speed. It also indicated to the researchers that none of the currently available magnetic field models adequately describe the characteristics of this black hole, highlighting the need for additional mathematical modeling. Janssen notes that earlier studies had merely narrowed down the potential characteristics of Sagittarius A*, such as its rotation speed and surrounding magnetic fields, while this new methodology has refined those estimates.

Dimitrios Psaltis from Georgia Tech in Atlanta remarked that some of the findings were unexpectedly counterintuitive. Previous analyses had not clarified whether black hole spins could be accurately discerned from EHT data.

While earlier research suggested that Sagittarius A* might be spinning at significant speeds,
Mizuno Yuishi from Zhejiang University in Shanghai, China, noted that there is still room for enhancement in the computational models applied in this new analysis. “Our theoretical model is still not perfect,” he acknowledged.

However, both Mizuno and Psaltis agree that integrating AI into the study of exotic cosmic entities like black holes is increasingly essential. “We possess a wealth of data and numerous models, and we require a contemporary approach to merge the two,” Psaltis states. “This is precisely where machine learning proves to be transformative.”

Yet, this integration presents unique challenges, as AI work necessitates verification to mitigate potential inaccuracies and errors in subsequent analysis.

Janssen and his team have conducted numerous verification checks, including testing the AI with specially designed simulation data. They are also evaluating data from subsequent EHT operations and will be analyzing new findings from observatory results, he explains.

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Source: www.newscientist.com

New Research Hints That Our Milky Way May Avoid Collision with Andromeda Galaxy

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The Milky Way galaxy is often believed to be on a collision path with the neighboring Andromeda galaxy. This merger, anticipated roughly 5 billion years in the future, is expected to create a new elliptical galaxy. However, recent studies indicate that the likelihood of such a catastrophic event may be less than previously assumed.

These images depict three encounter scenarios between the Milky Way galaxy and the neighboring Andromeda galaxy. Top left: Messier 81 and Messier82. TopRight: NGC6786. BOTTOM: NGC 520. Image credits: NASA/ESA/STSCI/DSS/Till Sawala, Helsinki University/Joseph Depasquale, STSCI.

The Milky Way navigates through space, its trajectory affected by the gravitational forces from nearby galaxies, including Andromeda, Triangulum, and the Large Magellanic Cloud.

Consequently, prior studies have proposed for over a decade that the Milky Way is likely to collide with Andromeda, forming a new elliptical galaxy referred to as Milkomeda in about 5 billion years.

Dr. Thiru Sawara, an astronomer at the University of Helsinki, stated:

In their latest research, Dr. Sawara and colleagues utilized updated data from the ESA Gaia satellite and the NASA/ESA Hubble Space Telescope to model the Milky Way’s movement through space over the next 10 billion years, while also refining estimates of the masses of local galaxies.

They discovered that there is about a 50% chance that no collision will occur between the Milky Way and Andromeda during this time frame.

The authors suggest that previous analyses overlooked certain calculations and uncertainties, including the gravitational influence of the Large Magellanic Cloud (a smaller galaxy orbiting the Milky Way).

They also propose that a merger with the Magellanic Clouds is nearly certain within the next two billion years, prior to any potential interaction with Andromeda.

“Even with the latest and most precise observational data at hand, the future of local galaxy groups remains uncertain,” Dr. Sawara remarked.

“Interestingly, there are roughly equal probabilities of widely discussed merger scenarios or, conversely, scenarios where the Milky Way and Andromeda remain unaffected.”

The team’s findings will be featured this week in the journal Nature Astronomy.

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T. Sawara et al. There is no certainty regarding the Milky Way and Andromeda collision. Nature Astronomy. Published online on June 2, 2025. doi:10.1038/s41550-025-02563-1

Source: www.sci.news

Webb finds a Milky Way-like spiral galaxy in ancient universes

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Astronomers using the NASA/ESA/CSA James Webb Space Telescope discovered a very ancient grand design spiral galaxy that existed just a billion years after the Big Bang. Named Zhúlóng (Torch Dragon), this galaxy is the most distant bulging disc galaxy candidate for which spiral arms have been known to date.

This image of Zhúlóng, the furthest spiral galaxy discovered to date, shows its very well-defined spiral arm, old bulge in the middle, and a large star-forming disc resembling the structure of the Milky Way. Image credits: NASA/CSA/ESA/M. Xiao, University of Geneva/G. Brammer, Niels Bohr Institute/Dawn JWST Archive.

Large spiral galaxies like our Milky Way are expected to take billions of years to form.

For the first billion years of universe history, galaxies are considered small, chaotic and irregular.

However, Webb is beginning to reveal very different photos.

Telescope deep infrared imaging reveals surprisingly large and well-structured galaxies much earlier than previously expected.

Among these new findings is Zhúlóng, the most distant spiral galaxy candidate ever identified, seen at a redshift of 5.2.

Despite this early period, galaxies exhibit surprisingly mature structures. Old bulge in the middle, large star-forming discs, spiral arms – a feature usually found in nearby galaxies.

“What stands out for Zhúlóng is both how similar it is to the Milky Way, its shape, size and star mass,” says Dr. Mengyuan Xiao, a postdoctoral researcher at Unige.

“The disc spans over 60,000 light years, comparable to our own galaxy, and the star contains over 100 billion solar masses.”

“This makes it one of the most persuasive Milky Way analogs discovered at such an early age, raising new questions about how a large, ordered spiral galaxy will form right after the Big Bang.”

The Zhúlóng Galaxy was discovered as part of a panoramic investigation.

“The findings highlight the possibility of purely parallel programs to reveal rare, distant objects that stress-test galaxy formation models,” says Dr. Christina Williams, a No-Arab astronomer and lead researcher of the Panorama Program.

Spiral structures were previously thought to take billions of years, but large galaxies were not expected to exist much later in the universe.

“The discovery shows that Webb is fundamentally changing the way we see the universe in its early days,” says Professor Pascal Oesch, an astronomer at Unige and a co-researcher of the Panorama Program.

a paper The discovery was published in the journal today Astronomy and Astrophysics.

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Mengyuan Xiao et al. 2025. Panorama: Discovery of a super gentle grand design spiral galaxy from z to 5.2. A&A 696, A156; doi:10.1051/0004-6361/202453487

Source: www.sci.news

A Runaway Magnetar Travels Across the Milky Way, Origin Point Unknown, According to Astronomers

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SGR 0501+4516 is the most likely candidate for Magnetaru’s Milky Way galaxy, which was not born from the supernova explosion, as originally predicted. The object may be very strange and may provide clues to the mechanism behind the fast radio bursts.

Impressions of Magneter artists. Image credit: ESA.

“A magnetor is a neutron star made up entirely of neutrons. What makes Magnetar unique is the extreme magnetic fields,” says Dr. Ashley Chris, an astronomer at the European Center for Space Research and Technology.

The strangeness of SGR 0501+4516 was identified with the help of ESA’s Gaia spacecraft with the help of a sensitive instrument mounted on the NASA/ESA Hubble Space Telescope.

Initially, Magnetar was discovered in 2008 when NASA’s Swift Observatory discovered a fierce flash of gamma rays from the outskirts of the Milky Way.

As magnetors are neutron stars, the natural explanation for their formation is that they are born in Supernova, where stars can explode and even collapse into ultra-density neutron stars.

This looked like the case of SGR 0501+4516, located near the supernova remnants called HB9.

The separation between the sky magnetor and the center of the supernova remnants is only 80 arcs, or slightly wider than the pinky finger, when seen at the edge of the extended arm.

However, a decade of research with Hubble questions Magnetall’s birthplace.

After the initial observation using ground-based telescopic tunables shortly after the discovery of SGR 0501+4516, astronomers used Hubble’s exquisite sensitivity and stable points to find the faint infrared glow of Magnetaral in 2010, 2012, and 2020.

Each of these images was arranged in a reference frame defined by observations from Gaia Spacecraft. GaiaSpacecraft has created a highly accurate 3D map of almost 2 billion stars in the Milky Way.

This method revealed subtle movements of magnets as they crossed the sky.

“All of this movement we measure is smaller than a pixel in a Hubble image,” said Dr. Joe Lyman, an astronomer at Warwick University.

“The ability to perform such measurements robustly is truly a testament to Hubble’s long-term stability.”

By tracking the magnetor’s location, astronomers were able to measure the apparent movement of the object across the sky.

Both the velocity and direction of movement of SGR 0501+4516 indicated that the magnetor was not associated with the remains of nearby supernova.

Tracking the magnetor’s trajectory thousands of years in the past showed that there were no other supernova remnants or large star clusters that it could be associated with.

If SGR 0501+4516 was not born on a supernova, the magnetors must be older than the estimated age of 20,000, or they may have been formed in a different way.

Magnetors can also be formed through a process called amalgamation or accretion-induced decay of two low-mass neutron stars.

Acceleration-induced decay requires a binary star system containing white dwarves.

When a white dwarf pulls gas from its companions, it grows too large to support itself, leading to an explosion, or perhaps a magnet.

“This scenario usually leads to a nuclear reaction ignition and a white d star explosion, leaving nothing behind,” said Dr Andrew Levan, an astronomer at Ladboo University and Warwick University.

“However, it is theorized that under certain conditions, white dwarfs may instead collapse into neutron stars. I think this is how SGR 0501+4516 was born.”

SGR 0501+4516 is currently the best candidate for galaxy magnetarals and may have been formed by a merger or an adductive decay.

The magnets formed through accretion-induced decays can provide some explanation for the mystical fast radio bursts, which are short but powerful flashes of radio waves.

In particular, this scenario may explain the origins of fast radio bursts that emerge from a group of stars that are too old to recently create a huge star to explode as a supernove.

“The magnetor’s fertility and formation scenarios are one of the most pressing issues of high-energy astrophysics, affecting many of the most powerful temporary events in the universe, including gamma-ray bursts, superilluminating supernovas and fast radio bursts.”

Survey results It will be displayed in the journal Astronomy and Astrophysics.

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aa chrime et al. 2025. Magnetor SGR 0501+4516 infrared support and proper movement. A&A 696, A127; doi: 10.1051/0004-6361/202453479

Source: www.sci.news

Gaia ceases operations after completing decade-long mapping of the Milky Way

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From ancient creeks of stars to the innards of white dwarfs, the Gaia Space Telescope has seen it all.

On Thursday, the European Space Agency’s mission specialists will send the low-fuel Gaia into orbit around the Sun, turning it off to astronomers around the world after more than a decade of service.

Gaia has been charting the universe since 2014, creating a vast encyclopedia of the position and movement of celestial objects from the Milky Way and beyond. It is difficult to grasp the breadth of development and discovery that a spinning observatory is enabled. But here are a few numbers: nearly 2 billion stars, millions of potential galaxies, and around 150,000 asteroids. These observations were brought Over 13,000 studies so far by astronomers.

Gaia changed the way scientists understand the universe, and that data became the reference point for many other telescopes on the ground and in the universe. Additionally, less than a third of the data collected has been released to scientists so far.

“It now supports almost everything in astronomy,” says Anthony Brown, an astronomer at Leiden University in the Netherlands, heading Gaia’s data processing and analysis group. “If you were to ask my astronomy colleagues, I don’t think they could have imagined that Gaia would have to do her research even if she wasn’t there.”

Starting in 2013, Gaia’s main goal was to uncover the history and structure of the Milky Way by constructing the most accurate, three-dimensional map of the position and velocity of 1 billion stars. As there is only a small portion of that data, astronomers Halo mass of dark matter We swallowed and identified our galaxy Thousands of trespassing stars ingested from another galaxy 10 billion years ago.

Dr. Brown measures continuous vibrations on the Milky Way disk and measures a kind of galactic seismology – evidence Of encounters with satellite galaxies that have put ourselves in orbit much more recently than scientists believed. That may be the reason for the Milky Way It looks distorted When viewed from the side.

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Source: www.nytimes.com

Previously underestimated activity of ultra-large black holes discovered in the Milky Way

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According to an analysis of new data from NASA/ESA/CSA James Webb Space Telescope, the ejaculation ability that orbits Sagittarius a* emits a constant flow of flares with no period of rest. Some flares are faint flickering for a few seconds, while others are blindly bright eruptions that spit out every day. There is also slight flicker than the surges for several months at a time.

The artist's concept depicts an ultra-high Massive black hole in the heart of the Milky Way galaxy known as Sagittarius a*. Image credits: NASA/ESA/CSA/RALF CRAWFORD, STSCI.

“We expect flares to occur in essentially every super-large black hole, but our black holes are unique,” says Dr. Farhad Yousef Zadeh, an astronomer at Northwestern University. Ta.

“It's always bubbled up with activity and doesn't seem to reach a stable state.”

“We observed Sagittarius A* multiple times throughout 2023 and 2024, and noticed changes in all observations.”

“We saw something different each time, and that's really surprising. It didn't stay the same.”

Dr. Yousefzadeh and his colleagues used it Webb's nircam instrument Observe Sagittarius A* in total of 48 hours, increments of 8-10 hours over a year.

They expected to see the flare, but Sagittarius A* was more active than he had expected.

The accretion disk surrounding the black hole produced 5-6 large flares per day, during which several small subflares were generated.

“Our data showed constantly changing and bubbly brightness,” Dr. Yusef-Zadeh said.

“And boom! A huge explosion of brightness suddenly appeared. Then it settled down again. No patterns were found in this activity. It seems random. The activity profile of the black hole is what we see every time we see it. It was new and exciting.”

“It appears to be caused by two separate processes: short bursts and long flares. If the accretion disk is a river, the short, faint flicker is like a small ripple that fluctuates randomly on the surface of the river. .”

“But longer, brighter flares are like tidal waves caused by more important events.”

“Mild faults in the accretion disk can produce faint flickers. Specifically, turbulent fluctuations within the disk cause plasma (high-temperature charge gas) to be compressed and temporary. It can cause a burst of radiation.”

“This is similar to the way the solar magnetic fields gather together to compress and eject solar flares.”

“Of course, the environment around the black hole is much more energetic and extreme, so the process is more dramatic. But the surface of the sun also bubbles up with activity.”

Astronomers attribute large, bright flares to magnetic reconnection events. This is the process in which two magnetic fields collide and release energy in the form of accelerated particles. These particles, moving at a speed close to the speed of light, emit a burst of bright radiation.

“The magnetic reconnection event is like a static electricity spark, and in some ways it is also an electrical reconnection,” Dr. Yusef-Zadeh said.

The team wants to use Webb to observe Sagittarius A* for a long period of time.

“When you're watching such a weak flare event, you have to compete with the noise,” said Dr. Yousef Zadeh.

“If you can observe 24 hours a day, you can reduce the noise and see features that you didn't see before. That would be great. Also, these flares show periodicity (or repeat yourself) or really You can also check if it is random.”

Survey results It will be published in Astrophysics Journal Letter.

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F. Yusef-Zadeh et al. 2025. Nonstop Variation of SgrA** Uses JWST at wavelengths of 2.1 and 4.8 microns: evidence of clear populations of faint and bright variable emissions. apjlin press; Arxiv: 2501.04096

Source: www.sci.news

XMM-Newton discovers two supernova remnants near the Milky Way satellite galaxy’s edge

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Named SNR J0614-7251 and SNR J0624-6948, the newly discovered supernova remains are located on the outskirts of the large Magelanic Cloud, the largest milky white satellite galaxy.

In the center of the image, stars cluster into a large Magellan cloud, a bright, dark green candy floss colored haze. Scattered in the center of the image are about 50 small yellow crosses, some of which are almost overlapping as they are very close to each other. SNR J0624-6948 (orange, high image) and SNR J0614-7251 (blue, bottom image) are seen in the lower left quarter of the image. Image credits: Eckhard Slawik/ESA/Xmm-Newton/Sasaki et al. / F. Zangrandi.

“Supranovae are stellar explosions, caused by massive star core collapse, neutron stars or black holes (core collapsing supernovae), or by thermonuclear destruction of white nuclei in binary systems. Friedrich- “We are a scientist at the same time,” said Alexander-Universität Erlangen-Nürnberg and colleague Dr. Manami Sasaki.

“Supranovae are important for galaxy material cycles and the formation of next-generation stars. Shockwave produces supernova debris that heats environmental or interstellar media to ionize, sweeping and compressing the environment, and making the environment more environmentally friendly and compressing. Enrich it. With chemical elements.”

use ESA's XMM-Newton Spaceshipastronomers discovered two supernova remnants, SNR J0614-7251 and SNR J0624-6948, in the large Magellan cloud.

“The big and small Magellan clouds are the largest satellite galaxies in the Milky Way and the closest ones,” they said.

“The Magellan Cloud is also the only satellite galaxy in the Milky Way with current active star formation.”

“A large Magellan cloud at a small distance (49,600 Parsec), its morphology is almost a hassle disk, and its low foreground absorption provides a detailed laboratory ideal for the study of large samples of the remaining supernovae. Masu.”

“Proximity allows for spatially resolved spectroscopic studies of supernova debris, and precisely known distances allow for the analysis of the energetics of each supernova debris.”

“In addition, the rich data of wide-field multi-wavelength data available provides information about the environment in which these supernova debris evolves.”

XMM-Newton observed SNR J0614-7251 and SNR J0624-6948 with three different types of X-ray light.

They show the most common chemical elements in various parts of the debris.

The center of SNR J0614-7251 is primarily made up of iron, according to the team.

This clue allowed researchers to classify this remnant for the first time as a result of a type IA supernova.

“The discovery of supernova remnants on the outskirts of the large Magellan cloud confirms that stellar explosions occur outside the galaxy and allows us to study their shocks, stellar ejectors and environment,” they said. I said that.

“It will help us to better understand the evolution of the Magellan cloud and the history of interacting galaxies and their surrounding star formation.”

“We hope that new multi-wavelength investigations will reveal more supernova remnants around the Magellan cloud.”

“This new supernova remnants allows us to study the supernova explosions and the rest of the supernova evolution in low density and low metallic environments, and better serve to better the effects of metallicity on star formation and star evolution. I can understand it.”

result It will be displayed in the journal Astronomy and Astrophysics.

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Manamisasaki et al. 2025. The remains of a supernova on the outskirts of the large Magellan cloud. A&A 693, L15; doi: 10.1051/0004-6361/202452178

Source: www.sci.news

Gaia Announces Most Detailed Map of Milky Way to Date, Achieves Skyscan Milestone in Mission

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Released on December 19, 2013, ESA's star mapping satellite “Gaia” We are now nearing the sky, but this does not mean the mission is complete. Technical tests are scheduled in the weeks before Gaia moves into its “retirement” orbit, with two major data releases scheduled for around 2026 and the end of the century, respectively.

An artist's impression of the Milky Way galaxy based on data from ESA's Gaia Space Telescope. Image credit: ESA / Gaia / DPAC / Stefan Payne-Wardenaar.

ESA Director of Science Carol Mandel said: “Today, as the science observations conclude, we celebrate this amazing mission that has exceeded all our expectations, extending almost twice its original predicted lifetime.” said.

“The treasure trove of data collected by Gaia has given us unique insight into the origin and evolution of the Milky Way galaxy, and has also provided insight into astrophysics and the solar system in ways we still don't fully understand. It transformed science.”

“Gaia is built on Europe’s unique excellence in astronomical measurements and will leave a lasting legacy for future generations.”

“After 11 years in space, surviving micrometeorite impacts and solar storms along the way, Gaia has completed collecting scientific data,” said Gaia project scientist Johannes Sahlmann.

“All eyes are now on preparing for the next data release.”

“We are excited to carry out this incredible mission and are excited about the discoveries that await us.”

An annotated artist's impression of the Milky Way galaxy, based on data from ESA's Gaia Space Telescope. Image credit: ESA / Gaia / DPAC / Stefan Payne-Wardenaar.

Gaia has used the three instruments many times over the course of its mission to observe and chart the stars' positions, distances, movements, changes in brightness, compositions, and numerous other characteristics.

This will allow Gaia to achieve its primary goal of building the largest and most accurate map of the Milky Way, displaying our home galaxy like no other mission has been able to achieve to date. is completed.

“Gaia has changed our impression of the Milky Way, so it contains major changes from previous models,” said Stefan Payne Waldenaar, a science visualizer at the House of Astronomy and the IAU Directorate of Astronomy Education. said.

“Even basic ideas such as the rotation of the galaxy's central bar, the distortion of the disk, the detailed structure of the spiral arms, and the interstellar dust near the sun have been revised.”

“Still, we are still speculating about the distant parts of the Milky Way based on incomplete data.”

“As more Gaia data is released, our view of the Milky Way will become even more accurate.”

Gaia's science and engineering teams are already hard at work preparing for Gaia Data Release 4 (DR4), scheduled for 2026.

The amount and quality of data is increasing with each release, and Gaia DR4, with an expected 500 TB data product, is no exception.

Additionally, it will cover the first 5.5 years of the mission, which is the length of the mission as originally planned.

“This is the release of Gaia that the community has been waiting for, but it's exciting considering it only covers half of the data collected,” said Dr. Antonella Valenari, an astronomer at the National Institute of Astronomical Sciences. Ta.

“Although the mission is currently suspending data collection, it will be business as usual for many years to come as we continue to make these impressive datasets available.”

Over the past decade, Gaia has accumulated more than 3 trillion observations of nearly 2 billion stars and other astronomical objects, revolutionizing the way we see our home galaxy and neighboring universe, and advancing its mission. You have completed the empty scan stage. Image credit: ESA / Gaia / DPAC / Stefan Payne-Wardenaar.

After several weeks of testing, Gaia will leave its current orbit around Lagrangian Point 2, 1.5 million km from Earth, away from the Sun and be placed into a final heliocentric orbit far from Earth's sphere of influence. .

The spacecraft is scheduled to be passivated on March 27, 2025 to avoid harm or interference with other spacecraft.

During the technical test, Gaia's orientation is changed, temporarily making it several orders of magnitude brighter and making it much easier to observe with small telescopes.

Gaia mission manager Uwe Lammers said: “Gaia will shine among the stars before her sad retirement and will treat us with this final gift to bid her farewell.”

“This is a moment to celebrate this transformative mission and to thank all the teams who have worked hard for more than a decade to operate Gaia, plan observations, and ensure the smooth return of valuable data to Earth.”

Source: www.sci.news

Astronomers delve into the three-dimensional makeup of the Milky Way galaxy

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Using data from the APOGEE survey, astronomers from the Potsdam Leibniz Institute for Astrophysics, the University of Vienna, and the Paris Observatory reconstructed the properties of “hidden” stars within the Milky Way’s disk.

Several real star orbits are shown on the overall starlight of the Milky Way galaxy. Image credit: S. Khoperskov / AIP.

“With each dramatic increase in the number of stars, our understanding of the Milky Way has improved,” said Dr. Sergei Khopelskov of the Potsdam Leibniz Institute for Astrophysics and his colleagues.

“From the earliest observations to increasingly advanced space and ground-based telescopes, each milestone has revealed new layers of the galaxy’s complex structure and motion.”

“Although the amount of star research continues to expand, our view of the Milky Way remains very vague because most of the stars we can study are concentrated around the Sun.”

“This discrepancy is primarily due to fundamental limitations in our observations resulting from our position in the central plane of the Milky Way’s disk.”

“At our location, the amount of stars we might be able to observe is limited by their brightness, but also by the possibility of interstellar medium blocking or dimming, called annihilation. It is affected by dust and gas.”

The authors have developed an innovative method to fill gaps in our understanding of the Milky Way’s structure.

“Rather than relying solely on observations of individual stars, we can use the entire orbits of actual stars to represent the structure and dynamics of galaxies,” they explained.

“As stars move around the center of the galaxy, they serve as a tool for mapping areas of the galaxy that our telescopes cannot directly reach, including areas on the opposite side of the Milky Way.”

“Using a model of the Milky Way’s mass distribution and observed star positions and velocities, we not only calculated the stars’ orbits, but more importantly, how much mass is associated with each orbit. I measured what I should do.”

Using a new technique, we apply it to a large sample of stars using spectroscopic parameters from the star. APOGEE surveyThis is part of the Sloan Digital Sky Survey, in which researchers mapped the kinematics of stars across the Milky Way.

They revealed the complex motion of stars within the bar region, unhindered by distance measurement uncertainties.

Astronomers quantified the galaxy’s mass-weighted chemical abundance and age structure by reconstructing the star’s orbit using real Milky Way stars with precisely determined parameters.

This approach avoids the challenges posed by dense interior regions and the disappearance of the interstellar medium, and provides a comprehensive view of the stellar population, including previously unobservable regions on the Milky Way’s far side.

“You can look at this approach from a different perspective,” Dr. Hopelskov said.

“Imagine that for every star we observe, there is a large sample of stars that follow the exact same orbits but were not captured by surveys for various reasons.”

“What we’re doing is reconstructing the positions, velocities and stellar parameters of these invisible stars and filling in the missing parts of the galaxy’s structure.”

“The new data strongly suggest that the Milky Way formed in two distinct stages, as evidenced by the different age and chemical abundance relationships.”

“The inner disk lies well inside the Sun’s radius and formed relatively quickly during the early stages of galactic evolution.”

“About 6 to 7 billion years ago, the outer disk began to assemble, rapidly expanding the radial extent of the Milky Way and forming its current structure.”

Source: www.sci.news

Binary star system found in close proximity to the central black hole of the Milky Way galaxy

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Using data from ESO’s Very Large Telescope (VLT) and the Keck Telescope, astronomers detected a binary star system in the S star cluster near Sagittarius A*, the supermassive black hole at the center of the Milky Way. I discovered it. This is the first time that a binary star has been discovered near a supermassive black hole.

This image shows the location of binary star D9 orbiting Sagittarius A*, the supermassive black hole at the center of the Milky Way. Image credit: ESO / Peißker et al. / S. Guizard.

Sagittarius A* is orbited by fast stars and dusty objects collectively known as the S cluster.

Binary star systems (two stars gravitationally bound to each other around a common center of mass) are predicted to exist within the S cluster, but have not been detected so far.

Previous studies have suggested that such stars are unlikely to be stabilized by their interactions with Sagittarius A*.

“Black holes are not as destructive as we think,” says Florian Peisker, an astronomer at the University of Cologne.

“Our findings show that some binaries can temporarily thrive even under disruptive conditions.”

The newly discovered binary star, named D9, is estimated to be just 2.7 million years old.

Due to the strong gravity of the nearby black hole, it will probably merge into a single star within just a million years, a very short time for such a young system.

“This only provides a short window on the cosmic timescale for observing such binary star systems, but we succeeded,” said Dr. Emma Bordier, also from the University of Cologne. Ta.

“The D9 system shows clear signs of gas and dust surrounding the star, suggesting it may be a very young system that must have formed near a supermassive black hole. ” said Dr. Michal Zajacek. Astronomer at Masaryk University and the University of Cologne.

The most mysterious of the S clusters are the G objects, which behave like stars but look like clouds of gas and dust.

It was while observing these mysterious objects that the research team discovered a surprising pattern in D9.

“This result sheds new light on what the mysterious G-objects are,” the authors said.

“They may actually be a combination of binaries that have not yet merged and leftover material from stars that have already merged.”

“Planets often form around young stars, so this discovery allows us to speculate about their existence,” Dr. Pisker said.

“It seems like it’s only a matter of time before planets are detected at the center of the galaxy.”

a paper This discovery was published in today’s magazine nature communications.

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F. Peisker others. 2024. A binary star system in the S star cluster near the supermassive black hole Sagittarius A*. Nat Commune 15, 10608; doi: 10.1038/s41467-024-54748-3

Source: www.sci.news

Webb’s discovery of brown dwarf candidates hints at first wealthy population outside of the Milky Way

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Astronomers using the NASA/ESA/CSA James Webb Space Telescope detected a population of 64 brown dwarf candidates with masses ranging from 50 to 84 Jupiter masses in the star cluster NGC 602.

This image of NGC 602 includes data from Webb's NIRCam (near-infrared camera) and MIRI (mid-infrared instrument) instruments. Image credits: NASA / ESA / CSA / Webb / P. Zeidler / E. Sabbi / A. Nota / M. Zamani, ESA & Webb.

NGC602 is a very young star cluster, about 200,000 light-years away in the constellation Hydra, about 2 to 3 million years old.

Also known as ESO 29-43, this star resides in the wings of the Small Magellanic Cloud.

NGC 602's local environment closely resembles that of the early Universe, with very low abundances of elements heavier than hydrogen and helium.

The presence of dark clouds of dense dust and the fact that the cluster is rich in ionized gas also suggests the presence of an ongoing star formation process.

Together with the associated HII region N90, which contains clouds of ionized atomic hydrogen, this cluster provides a rare opportunity to examine star formation scenarios under conditions dramatically different from those in the solar neighborhood.

Using Webb, Dr. Peter Zeidler and his colleagues at AURA and ESA were able to detect 64 brown dwarf candidates in NGC 602. This is the first rich population of brown dwarfs to exist outside the Milky Way.

“It is possible to detect objects at such great distances only with incredible sensitivity and spatial resolution in the right wavelength range,” Dr. Zeidler said.

“This has never been possible and will remain impossible from the ground for the foreseeable future.”

“So far, about 3,000 brown dwarfs are known, and they all live in our galaxy,” said Dr. Elena Mangiavakas, also from AURA and ESA.

“This discovery highlights the ability to use both Hubble and Webb to study young star clusters,” said Dr. Antonella Nota, executive director of the International Space Science Institute.

“Hubble showed that NGC 602 hosts very young, low-mass stars, but only Webb can conclusively confirm the extent and significance of substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”

“Our results are very consistent with the theory that the mass distribution of objects below the hydrogen burning limit is simply a continuation of the stellar distribution,” Dr. Zeidler said.

“They seem to form the same way, they just haven't accumulated enough mass to become full stars.”

NSF astronomer Dr. Elena Sabbi said, “Studying the newly discovered metal-poor young brown dwarfs in NGC 602 will shed light on how stars and planets formed under the harsh conditions in the early universe. We are getting closer to uncovering the secrets of this.” NOIRLab, University of Arizona, Space Telescope Science Institute.

“These are the first substellar objects outside the Milky Way,” Manjavakas said.

“We need to be prepared for new breakthrough discoveries in these new objects.”

of result will appear in astrophysical journal.

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peter zeidler others. 2024. A candidate for a subsolar metallic brown dwarf is discovered in the Small Magellanic Cloud. APJ 975, 18; doi: 10.3847/1538-4357/ad779e

Source: www.sci.news

New study suggests Milky Way’s thinner disk formed within one billion years of the Big Bang

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Use of Data ESA's Gaia mission Astronomers have discovered a number of metal-poor stars that are more than 13 billion years old and in orbits similar to our sun.

Rotational motion of a young (blue) and an older (red) star similar to the Sun (orange). Image credit: NASA / JPL-Caltech / R. Hurt / SSC / Caltech.

“The Milky Way has a large halo, a central bulge and bar, and thick and thin disks,” said Dr Samir Nepal of the Leibniz Institute for Astrophysics Potsdam and his colleagues.

“Most of the stars are found in a thin disk of the so-called Milky Way galaxy, which revolves regularly around the galactic center.”

“Middle-aged stars like our Sun, which is 4.6 billion years old, belong to a thin disk that is generally thought to have begun to form between 8 and 10 billion years ago.”

Astronomers used the new Gaia data set to study stars within about 3,200 light-years of the Sun.

They found a surprisingly large number of very old stars in the thin disk orbit, most of which are over 10 billion years old, with some being over 13 billion years old.

These ancient stars show a wide range of metal compositions: some are very metal-poor (as expected), while others have twice the metal content of the much younger Sun, indicating that rapid metal enrichment occurred early in the evolution of the Milky Way.

“These ancient stars in the disk suggest that the formation of the Milky Way's thin disk began much earlier than previously thought, around 4 to 5 billion years ago,” Dr Nepal said.

“This study also reveals that the Galaxy underwent intense star formation early on, leading to rapid metal enrichment in its inner regions and the formation of a disk.”

“This discovery brings the Milky Way's disk formation timeline into line with that of high-redshift galaxies observed with the NASA/ESA/CSA James Webb Space Telescope and the Atacama Large Millimeter Array (ALMA).”

“This shows that cold disks can form and stabilize very early in the history of the universe, providing new insights into the evolution of galaxies.”

“Our study suggests that the Milky Way's thin disk may have formed much earlier than previously thought and that its formation is closely linked to an early chemical enrichment in the innermost regions of the galaxy,” said Dr Cristina Chiappini, astronomer at the Leibniz Institute for Astrophysics Potsdam.

“The combination of data from different sources and the application of advanced machine learning techniques has allowed us to increase the number of stars with high-quality stellar parameters, which is an important step leading our team to these new insights.”

of paper will be published in journal Astronomy and Astrophysics.

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Samir Nepal others2024. Discovery of local counterparts of disk galaxies at z > 4: The oldest thin disk in the Milky Way using Gaia-RVS. A&Ain press; arXiv: 2402.00561

Source: www.sci.news

Intermediate-sized black hole found in the heart of the Milky Way Galaxy

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Using data from the European Southern Observatory's Very Large Telescope (VLT) and other telescopes, astronomers have found evidence of an intermediate-mass black hole. IRS 13a dusty group of stars within the nuclear cluster of our Milky Way galaxy.

Intermediate-mass black holes can form in dense star clusters, either through the merger of stellar-mass black holes or the collapse of very massive stars. Image credit: Sci.News/Zdeněk Bardon/ESO.

Black holes are found in a wide range of masses, from stellar-mass objects with masses of 10 to 100 times that of the Sun, to objects at the centers of galaxies with masses over 100,000 times that of the Sun.

However, there are only a few intermediate-mass black hole candidates between 100 and 100,000 times the mass of the Sun.

“The IRS 13 cluster is located 0.1 light-years away from the centre of our galaxy,” said Dr Florian Peisker from the University of Cologne and his colleagues.

“I noticed that the stars in IRS 13 were moving in an unexpectedly orderly pattern.”

“They actually expected the stars to be randomly positioned.”

“Two conclusions can be drawn from this regular pattern,” they added.

“Meanwhile, IRS 13 appears to be interacting with Sagittarius A*, a black hole at the centre of the Milky Way that is four million times more massive than the Sun, which leads to the orderly motion of stars.”

“However, something else needs to be present inside the cluster to maintain the observed compact shape.”

Using data from the VLT, the Atacama Large Millimeter/submillimeter Array (ALMA), and NASA's Chandra X-ray Telescope, astronomers have found strong evidence that IRS 13 has a disk-like structure.

“Multi-wavelength observations suggest that the reason for IRS 13's compact shape could be an intermediate-mass black hole located at the center of the cluster,” the researchers said.

“We were able to observe characteristic x-rays and ionized gas rotating at hundreds of kilometers per second in the disk surrounding the suspected intermediate-mass black hole.”

“Another indication of the presence of an intermediate-mass black hole is the unusually high density of this cluster, which is higher than the density of any other cluster in our Milky Way galaxy.”

“IRS 13 appears to be an essential component in the growth of the central black hole, Sagittarius A*,” Dr Peisker said.

“This fascinating star cluster has continued to astonish the scientific community since its discovery almost 20 years ago. It was initially thought to be an unusually massive group of stars, but high-resolution data have now allowed us to confirm its component parts, with an intermediate-mass black hole at its center.”

of result Appears in Astrophysical Journal.

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Florian Peisker others2024. The evaporating massive embedded stellar cluster IRS 13 close to Sgr A*. II. Kinematic structure. ApJ 970, 74; doi: 10.3847/1538-4357/ad4098

Source: www.sci.news

Astronomers find intermediate-mass black hole in largest globular cluster in Milky Way

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Using more than 500 images from the NASA/ESA Hubble Space Telescope, astronomers have found evidence of a 20,000-solar-mass black hole at the center of Earth. Omega CentauriIt is a globular cluster located in the constellation Centaurus, 5,430 parsecs (17,710 light years) from the Sun.

Omega Centauri is about 10 times more massive than other large globular clusters. Image credit: NASA / ESA / Hubble / Maximilian Häberle, MPIA.

Astronomers know that stellar-mass black holes (black holes with masses between 10 and 100 times that of the Sun) are the remnants of dying stars, and that supermassive black holes, with masses more than a million times that of the Sun, exist at the center of most galaxies.

But the universe is littered with what appear to be more mysterious types of black holes.

These intermediate-mass black holes, with masses between 100 and 10,000 times that of the Sun, are so difficult to measure that their very existence is sometimes debated.

Only a few intermediate-mass black hole candidates have been discovered so far.

Determining the black hole population is an important step towards understanding the formation of supermassive black holes in the early universe.

“Omega Centauri is a special example among globular clusters in the Milky Way,” said astronomer Maximilian Höberle of the Max Planck Institute for Astronomy and his colleagues.

“Omega Centauri is widely accepted to be the stripped core of an accreted dwarf galaxy due to its high mass, complex stellar population and kinematics.”

“These factors, combined with its proximity, make the planet a prime target in the search for intermediate-mass black holes.”

Omega Centauri is made up of about 10 million stars, making it about 10 times more massive than any other large globular cluster.

In the study, the authors measured the velocities of 1.4 million stars from images of the cluster taken by the Hubble Space Telescope.

Although most of these observations were intended for calibration of Hubble's instruments rather than for scientific use, they proved to be an ideal database for the team's research activities.

“We looked for fast-moving stars that are expected to be near concentrated masses such as black holes,” said astronomer Holger Baumgart of the University of Queensland.

“Identifying these stars was the smoking gun we needed to prove the existence of black holes, and we've done just that.”

“We found seven stars that shouldn't be there,” Dr Hebel said.

“They're moving so fast that they're likely to escape the herd and never come back.”

“The most likely explanation is that a very massive object is gravitationally tugging on these stars, keeping them near the center.”

“The only objects this massive are black holes, which have a mass at least 8,200 times that of the Sun.”

“This discovery is the most direct evidence to date for the presence of an intermediate-mass black hole at Omega Centauri,” said Dr Nadine Neumayer, an astronomer at the Max Planck Institute for Astronomy.

“This is extremely exciting because very few other black holes with similar masses are known.”

“The black hole at Omega Centauri may be the best example of an intermediate-mass black hole in our cosmic neighborhood.”

Team paper Published in the journal Nature.

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M. Heberle others2024. Stars moving at high speed around the intermediate-mass black hole at Omega Centauri. Nature 631, 285-288; Source: 10.1038/s41586-024-07511-z

Source: www.sci.news

The Ideal Location of Our Milky Way Galaxy for Discovering Extraterrestrial Life

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CrackerClips Stock Media/Alamy

All life as we know it in the entire universe is tucked away on a tiny rock floating in a tiny branch of the Milky Way galaxy. There are billions of other planets that could potentially support life, but how does our location affect our chances of finding it?

So far, the search for life elsewhere has only scratched the surface. “The bubble of space we've been able to explore around the Sun is tiny compared to the size of our galaxy,” he said. Jesse Christiansen“But we've already discovered more than 5,000 planets, called exoplanets, that orbit other stars,” says John F. Kennedy, an astrophysicist at the California Institute of Technology. Some of these have been found throughout our galaxy and even in other galaxies, but most are within a few hundred light years of the sun, a stone's throw in the scheme of the universe.

Our Galactic Neighborhood

Astronomers are beginning to look at different types of stars in the galactic outskirts and how they affect the habitability of planets around them. We live in an arm of the Milky Way galaxy called Orion, inside the main plane of the galaxy called the thin disk. We are surrounded by stars in the Orion arm. Further outwards, we are surrounded by the dense bulge of the galaxy's dense core on one side, and the sparser outer parts of the other arms of the galaxy on the other side.

Thin, disk-shaped stars, like our Sun and other stars in the constellation Orion, generally…

Source: www.newscientist.com

Astrophysicist reveals the genesis of one of the Milky Way’s biggest moons

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Satellite Galaxy Crater II The Milky Way's Crater 2 (or Crater 2) is located in the constellation Crater, about 380,000 light-years from Earth. This galaxy is very cold, very diffuse, and has a low surface brightness. According to a new study, Crater 2 exists thanks to self-interacting dark matter.

Location of Crater II and other Milky Way moons at distances between 100,000 and 400,000 parsecs from the Sun. Image courtesy of Torrealba others., doi: 10.1093/mnras/stw733.

” discovery “Since 2016, there have been numerous attempts to recreate the anomalous properties of Crater II, but these have proven extremely difficult,” said Haibo Yu, a professor at the University of California, Riverside.

Dark matter makes up 85% of the matter in the universe, and under the influence of gravity it can form spherical structures called dark matter halos.

Invisible halos permeate and surround galaxies like Crater II, and the fact that Crater II is so cold indicates that its halo is low density.

“Crater II developed within the Milky Way's tidal field and experienced tidal interactions with its host galaxy, similar to how Earth's oceans experience tidal forces due to the Moon's gravity,” Professor Yu said.

“In theory, tidal interactions can reduce the density of dark matter haloes.”

However, recent measurements of Crater II's orbit around the Milky Way suggest that if dark matter is made of cold, collisionless particles, as predicted by the prevailing cold dark matter theory (CDM), the strength of the tidal interactions is too weak to reduce the dark matter density in the satellite galaxy enough to match the measurements.

“Another mystery is why Crater II is so large when, as the satellite galaxy evolves in the Milky Way's tidal field, tidal interactions should reduce its size,” said Professor Yu.

Professor Yu and his colleagues put forward a different theory to explain the properties and origin of Crater II.

This is called self-interacting dark matter (SIDM) and can plausibly explain the diverse distribution of dark matter.

The theory proposes that dark matter particles self-interact through the dark force and collide with each other forcefully near the center of the galaxy.

“Our study shows that SIDM can explain the anomalous properties of Crater II,” said Professor Yu.

“The key mechanism is that dark matter self-interaction thermalizes Crater II's halo and creates a shallow dense core, i.e. the dark matter density flattens out at a small radius.”

“In contrast, in a CDM halo, the density would increase rapidly towards the center of the galaxy.”

“In SIDM, the strength of the relatively weak tidal interaction, consistent with what is expected from measurements of Crater II's orbit, is sufficient to reduce the dark matter density in Crater II, consistent with observations.”

“Importantly, the size of galaxies is also increasing within the SIDM halo, which could explain the large size of Crater II.”

“Dark matter particles are only more loosely bound in the cored SIDM halo than in the pointed CDM halo.”

“Our study shows that SIDM is a better option than CDM for explaining the origin of Crater II.”

of study Published in Astrophysical Journal Letters.

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Zhang Xingyu others2024. Interpreting self-interacting dark matter in Crater II. Apu JL 968, L13; doi: 10.3847/2041-8213/ad50cd

Source: www.sci.news

The Milky Way’s most recent major merger occurred billions of years later than previously believed

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The discovery was made possible by ESA’s Gaia spacecraft, which is mapping more than a billion stars across the Milky Way galaxy and beyond, tracking their motions, brightness, temperature, and composition.

This image visualizes the Milky Way and its surrounding halo of stars. New Gaia data reveals that the wrinkles seen in the Milky Way are likely the result of a dwarf galaxy colliding with the Milky Way about 2.7 billion years ago. Our galaxy’s two major satellite galaxies, the Large and Small Magellanic Clouds, are visible at the bottom right. Image credit: ESA / Gaia / DPAC / Donlon other./ Stephen Payne Waldenaar.

The Milky Way galaxy has grown over time as other galaxies have approached, collided, been torn apart, and been swallowed up.

Each collision still sends ripples through different groups of stars, influencing their movements and behavior in space.

One of Gaia’s goals is to study these wrinkles to unravel the history of our Milky Way galaxy. It does this by pinpointing the positions and motions of more than 100,000 stars close to Earth, a tiny fraction of the roughly 2 billion objects it observes.

“As we age, we tend to get more wrinkles, but our research shows that the opposite is true in the Milky Way – it’s like a cosmic Benjamin Button, and it gets less wrinkled over time,” said Dr. Thomas Donlon, an astronomer at Rensselaer Polytechnic Institute and the University of Alabama.

“By looking at how these wrinkles fade over time, we can trace when the Milky Way last experienced a major collision — and it turns out this happened billions of years later than we thought.”

The Milky Way’s halo contains many stars with unusual orbits, many of which are thought to have been incorporated into the galaxy in an event that astronomers call the last great merger.

As the name suggests, this is the last time the Milky Way has experienced a significant collision with another galaxy, which is proposed to have been a giant dwarf galaxy that smothered the Milky Way with stars passing very close to the center of the Milky Way.

Astronomers estimate that the merger occurred between 8 and 11 billion years ago, when the Milky Way was still in its infancy, and is known as Gaia-Sausage-Enceladus.

But data from Gaia’s Data Release 3 suggests that another merger could have resulted in the unusually behaving star.

“For the stellar wrinkles to be as clear as we see in the Gaia data, the stars would have had to have appeared on Earth less than 3 billion years ago — at least 5 billion years later than previously thought,” said Dr. Heidi Jo Neuberg, also of Rensselaer Polytechnic Institute.

“Every time a star passes back and forth through the center of the Milky Way, a new stellar wrinkle forms.”

“If they had merged with us 8 billion years ago, there would have been so many wrinkles next to each other that we wouldn’t be able to see them as separate features.”

This discovery suggests that these stars did not result from the ancient Gaia-Sausage-Enceladus merger, but must have arisen from a more recent event called the Virgo radial merger, which occurred less than 3 billion years ago.

“The history of the Milky Way is currently being constantly rewritten, thanks in large part to new data from Gaia,” Dr. Donlon said.

“Our image of the Milky Way’s past has changed dramatically since even 10 years ago, and I think our understanding of these mergers will continue to change rapidly.”

“This finding that most of the Milky Way galaxy joined Earth within the last few billion years is quite different from what astronomers previously thought.”

“Many prevailing models and ideas about the growth of the Milky Way predict that a recent head-on collision with a dwarf galaxy of this mass would be extremely rare.”

“The Virgo radial merger likely pulled in a group of other small dwarf galaxies and star clusters, all of which joined the Milky Way at about the same time.”

“Future exploration will reveal which of these small objects previously thought to be related to the ancient Gaia sausage Enceladus are in fact related to the recent Virgo radial merger.”

of Investigation result Appears in Monthly Bulletin of the Royal Astronomical Society.

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Thomas Donlon otherThe year is 2024. The remains of the “last great merger” are dynamically young. MNRAS 531(1):1422-1439; doi:10.1093/mnras/stae1264

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Astronomers Find Milky Way Center is Ventilated

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Astronomers using NASA's Chandra X-ray Observatory have discovered an “exhaust vent” that directs hot gas away from Sagittarius A*, the supermassive black hole at the center of the Milky Way galaxy. The vent is about 26,000 light-years from Earth and is connected to a previously discovered chimney-like structure perpendicular to the galactic plane. Chandra's data shows a cylindrical tunnel that helps collect gas towards the outer edge of the Milky Way. The results reveal how the Milky Way's black hole takes in and rejects matter.

This image shows a region near the center of the Milky Way galaxy in X-rays and radio waves. At the bottom of the image, near the center, there are knots of shiny, tangled material that resemble paint splatters. This is the brightest region in the image and contains the supermassive black hole at the center of the galaxy known as Sagittarius A*. The bottom third of the image looks like an angry firestorm. Red and orange stripes were scattered in all directions, as if the embers of a fire had crackled and shot into the air all at once. A flame-like structure is licking from the right side towards the center. Most of the image is injected with a wispy blue cloud indicating his X-rays detected by Chandra. In some places, wispy blue clouds appear to form balls of blue-green light, known as dust rings. They are caused by X-rays from a bright X-ray source reflecting off the dust around them. These dust rings resemble underwater lights glowing in a cloudy pool at night. Rising from Sagittarius A* in the center of the image is a pillar of blue light called a chimney. This chimney of hot gas is surrounded by a red cloud filled with stars, appearing as a small red speck. Near the top of the blue pillar is a light blue stripe surrounded by an illustrated gray box. This line is called the chimney exhaust. Immediately to the left is another illustrated box showing a close-up image of the chimney vent that Chandra observed.Image credits: NASA / CXC / Chicago Space / Mackey other. / NRF / SARAO / MeerKAT / SAO / N. Walk.

The chimney begins at the center of the Milky Way and stands perpendicular to the galaxy's spiral disk.

Astronomers previously identified the chimney using X-ray data from NASA's Chandra mission and ESA's XMM Newton mission.

The radio emissions detected by the MeerKAT radio telescope show the influence of the magnetic field surrounding the gas in the chimney.

The latest Chandra data reveals several X-ray ridges nearly perpendicular to the galactic plane.

Astronomers believe these are cylinder-shaped tunnel walls that help collect hot gas as it moves upwards along the chimney and away from the center of the galaxy. .

The newly discovered vent is located near the top of a chimney about 700 light-years from the center of the galaxy.

“We suspected that the magnetic field was acting as a chimney wall, allowing hot gases to rise through it like smoke,” said Dr. Scott McKee, an astronomer at the University of Chicago.

“I just discovered an exhaust near the top of the chimney.”

Astronomers believe the vent formed when hot gas rising through the chimney collided with cooler gas in its path.

The brightness of the exhaust wall in X-rays is caused by the shock wave created by this collision, similar to the sonic boom from a supersonic airplane.

The left side of the exhaust port is thought to be particularly bright because the upwardly flowing gas hits the tunnel wall at a more direct angle and with more force than other areas.

The researchers believe that the hot gas originates from a series of events in which material falls into Sagittarius A*, then erupts from the black hole, sending gas upward along the chimney and out the exhaust vent. I think it is most likely that it did.

However, it is not known exactly how often black holes are fed.

Previous studies have shown that dramatic X-ray flares occur every few hundred years at or near the central black hole, so that these flares send hot gases upward through the exhaust vent. may play an important role in pushing up.

Astronomers also estimate that Sagittarius A* tears apart and swallows a star approximately every 20,000 years.

Such an event would lead to a powerful and explosive release of energy, much of which would rise through the chimney vent.

Dr Mark Morris, an astronomer at the institute, said: 'We don&#39t know whether this energy and heat is caused by a large amount of material being thrown into Sagittarius A* at once. It&#39s like being thrown into it.” University of California, Los Angeles.

“Alternatively, it could result from multiple small loads being fed into the black hole, similar to kindlings thrown in periodically.”

Particles and energy within the vents provide clues about the origins of two mysterious and much larger structures near the center of the Milky Way. Fermi bubbles observed in gamma-rays by NASA&#39s Fermi Gamma-ray Space Telescope, and eROSITA bubbles detected by NASA&#39s Fermi Gamma-ray Space Telescope. ESA&#39s eROSITA X-ray telescope.

These are both pairs of structures that extend thousands of light-years away from the center of our galaxy.

These provide important information about past explosive activity near the center of the galaxy.

Both the Fermi and eROSITA bubbles are aligned along the direction of the chimney and a second X-ray chimney that starts at the center of the galaxy and points in the opposite direction.

The funnel effect of the exhaust near the top of the chimney keeps the hot gases concentrated as they move upwards, which can promote the formation of a bubble agglomerate structure.

“The origin of the Fermi and eROSITA bubbles is one of the greatest mysteries facing the study of high-energy radiation from the Milky Way,” said Dr. Gabriele Ponti, an astronomer at Italy&#39s National Institute of Astrophysics.

“We discovered small structures that may play a major role in the creation of these giant bubbles.”

a paper Regarding the survey results, astrophysical journal.

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Scott C. McKee other. 2024. X-rays from the central “exhaust” of the chimney at the center of the galaxy. APJL 966, L32; doi: 10.3847/2041-8213/ad3248

Source: www.sci.news

Discovery of ancient star in Milky Way halo estimated to be 12-13 billion years old by astronomers

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Astronomers at the Massachusetts Institute of Technology have discovered very old stars in the Milky Way’s halo, a cloud of stars that covers the entire disk of our galaxy. These objects formed between 12 and 13 billion years ago, when the first galaxies were beginning to form. Researchers believe that each star once belonged to its own dwarf galaxy, which was later absorbed into the larger but ever-growing Milky Way, making them known as small accreting star systems (SASS). It’s called a star.

Artist’s concept of the Milky Way galaxy. Image credit: Pablo Carlos Budassi / CC BY-SA 4.0.

“Given what we know about galaxy formation, these oldest stars should definitely exist,” says MIT professor Anna Froebel.

“They are part of our cosmic family tree. And now we have a new way to find them.”

As they discover similar SASS stars, Professor Froebel and his colleagues hope to use them as analogues of ultrafaint dwarf galaxies, which are thought to be some of the first living galaxies in the universe.

These galaxies remain intact today, but they are too distant and faint for astronomers to study in detail.

SASS stars may once have belonged to similar primitive dwarf galaxies, but they are now located within the Milky Way and are much closer, making them more accessible for understanding the evolution of ultrafaint dwarf galaxies. This could be the key.

“Now we can look for more brighter analogs in the Milky Way and study their chemical evolution without chasing these very faint stars,” Professor Froebel said.

The low chemical abundances of these stars suggest that they first formed between 12 and 13 billion years ago.

In fact, their low chemical signature was similar to what astronomers had previously measured for several ancient, ultra-dark dwarf galaxies.

Are the team’s star players from similar galaxies? And how did they come to exist in the Milky Way?

Based on a hunch, scientists studied the orbital patterns of stars and how they move across the sky.

The three stars are located in different locations throughout the Milky Way’s halo and are estimated to be about 30,000 light-years from Earth.

When astronomers used observations from ESA’s Gaia satellite to trace the movement of each star around the galaxy’s center, they noticed something strange. All three stars appeared to be in motion, compared to most of the stars in the main disk, which move like cars on a race track. Wrong way.

In astronomy, this is known as retrograde motion, and is information that the object was once accreted or pulled in from elsewhere.

“The only way to get a star wrong from other members is if you throw it the wrong way,” Professor Froebel says.

The fact that these three stars orbit in a completely different way than the rest of the galactic disk or halo, combined with the fact that their chemical abundances are low, suggests that these stars are actually It was strongly argued that it was ancient and once belonged to an earlier era, a small dwarf galaxy that fell into the Milky Way at a random angle and continued its stubborn orbit billions of years later.

The authors were interested in whether retrograde motion was a feature of other ancient stars in the halo that astronomers had previously analyzed, and they looked at the scientific literature and found similarly low strontium and barium contents, discovered 65 other stars that appear to be moving in retrograde motion as well. Galaxy flow.

“Interestingly, they are all traveling very fast, hundreds of kilometers per second, in opposite directions,” Professor Froebel said.

“They’re on the run! We don’t know why it happened, but this is the piece of the puzzle we need and we never expected it when we started.”

Researchers are keen to find other ancient SASS stars, and now have a relatively simple recipe for doing so. First, they look for stars with low chemical abundance, then track their orbital patterns for signs of retrograde motion.

Researchers hope this method will uncover a small but significant number of the universe’s oldest stars, out of the more than 400 billion stars in the Milky Way.

“I really enjoyed working with three female undergraduates. It was a first for me,” said Professor Froebel.

“This is just an example of the MIT way. It is. And anyone who says, ‘I want to participate,’ can do so, and good things happen.”

team’s paper Published in Royal Astronomical Society Monthly Notices.

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Hilary Diane Anders other. 2024. The oldest star with a small amount of neutron-capturing elements and originating from an ancient dwarf galaxy. MNRAS 530 (4): 4712-4729; doi: 10.1093/mnras/stae670

Source: www.sci.news

New image exposes magnetic field surrounding Milky Way’s black hole

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New and impressive images of the supermassive black hole located at the center of our galaxy show that its powerful magnetic field twists and rotates in a spiral pattern.

This is a never-before-seen view of Sagittarius A* (or Sgr A*), the massive black hole in the Milky Way galaxy that consumes nearby light and matter.

The images suggest similarities in structure between this black hole and the black hole in the galaxy M87. Although the black hole in M87, which was imaged for the first time, is over 1,000 times larger than Sagittarius A*, both exhibit strong, organized magnetic fields.

This pattern hints that many, if not all, black holes may share common traits, according to the scientists who published their findings in the Astrophysics Journal Letter on Wednesday.

“We’ve discovered that strong, orderly magnetic fields are crucial in how black holes interact with surrounding gas and matter,” said study co-leader and NASA Hubble Fellowship Program co-author, Einstein Fellow Sarah Isaun, as stated in a press release.

Isaun worked with an international team of astronomers known as the Event Horizon Telescope to conduct the research. This team comprises over 300 scientists from 80 institutions worldwide.

This same collaboration captured the first direct visual evidence of Sagittarius A* in 2022 and also studied the M87 galaxy, which is located approximately 53 million light-years away from Earth.

The magnetic field around the massive black hole at the center of the M87 galaxy, known as M87*, is believed to play a vital role in its extraordinary behavior. Black holes emit powerful jets of electrons and other subatomic particles into space at nearly the speed of light.

Although no such bursts of activity have been observed from Sagittarius A*, the similarities between the two black holes suggest that hidden jets may still be detected. Researchers suggest this possibility in the new images.


Source: www.nbcnews.com

The Event Horizon Telescope Detects a Twisted Magnetic Field Surrounding the Central Black Hole of the Milky Way

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According to astronomers’ best models of black hole evolution, the magnetic field within the accretion disk must be strong enough to push the accreted plasma out into the surroundings. New results from Sagittarius A*, the 4.3 million solar mass black hole at the center of the Milky Way galaxy, and its much larger cousin M87* provide the first direct observational evidence supporting these models.

This image from the Event Horizon Telescope shows a polarized view of Sagittarius A*. The lines superimposed on this image show the direction of polarization associated with the magnetic field around the black hole’s shadow. Image credit: EHT Collaboration.

In 2022, EHT collaboration The first image of Sagittarius A*, about 27,000 light-years from Earth, has been released, showing that the Milky Way’s supermassive black hole looks very good despite being more than 1/1000th smaller and lighter in mass than M87. revealed that they are similar.

This led scientists to wonder if the two men had more in common than just their looks. To find out, they decided to study Sagittarius A* in polarized light.

Previous studies of the light surrounding M87* revealed that the magnetic field around the supermassive black hole causes powerful jets of matter to be ejected into the surrounding environment.

Based on this study, new EHT images reveal that the same may be true for Sagittarius A*.

“What we’re seeing now is a strong, twisted, organized magnetic field near the black hole at the center of the Milky Way,” said astronomers at the Harvard University & Smithsonian Center for Astrophysics. said Dr. Sarah Isaun.

“In addition to having a polarization structure that is strikingly similar to that seen in the much larger and more powerful M87* black hole, Sagittarius A* has a polarization structure that is strikingly similar to that seen in the much larger and more powerful M87* black hole. We found that strong, well-ordered magnetic fields are important for how they act.”

Light is a vibrating or moving electromagnetic wave that allows us to see objects. Light can oscillate in a particular direction, which scientists call polarization.

Polarized light is all around us, but to the human eye it is indistinguishable from “normal” light.

In the plasma around these black holes, particles swirling around magnetic field lines impart a polarization pattern perpendicular to the magnetic field.

This will allow astronomers to see in clearer detail what’s happening in the black hole region and map its magnetic field lines.

“By imaging polarized light from glowing gas near a black hole, we are directly inferring the structure and strength of the magnetic field that flows through the streams of gas and matter that the black hole feeds and ejects.” said Dr. Angelo Ricarte. Astronomer at Harvard University and the Harvard & Smithsonian Center for Astrophysics.

“Polarized light can tell us much more about astrophysics, the properties of the gas, and the mechanisms that occur when black holes feed.”

But imaging black holes under polarized light isn’t as easy as wearing polarized sunglasses. This is especially true for Sagittarius A*. Sagittarius A* changes so quickly that you can’t stand still and take a photo.

Imaging supermassive black holes requires sophisticated tools beyond those previously used to capture a more stable target, M87*.

“Sagittarius A*s are like enthusiastic toddlers,” said Avery Broderick, a professor at the University of Waterloo.

“For the first time, we see invisible structures that guide matter within a black hole’s disk, drive plasma to the event horizon, and help the plasma grow.”

“Sagittarius A* moves around while trying to photograph it, so it was difficult to even construct an unpolarized image,” said astronomer Dr. Jeffrey Bower of the Institute of Astronomy and Astrophysics, Academia Sinica in Taipei. Told.

“The first image is an average of multiple images from the movement of Sagittarius A*.”

“I was relieved that polarized imaging was also possible. Some models had too much scrambling and turbulence to build polarized images, but nature isn’t that cruel. did.”

Professor Maria Felicia de Laurentiis, University of Naples Federico II, said: “Using samples of two black holes with very different masses and host galaxies, we can determine what they agree on and what they do not agree on.” It’s important.

“Since both point us toward strong magnetic fields, this suggests that this may be a universal and perhaps fundamental feature of this type of system.”

“One similarity between these two black holes could be a jet. But while we imaged a very obvious black hole in M87*, we have yet to find one in Sagittarius A*. not.”

The results of this research are published in two papers (paper #1 & paper #2) in Astrophysics Journal Letter.

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Collaboration with Event Horizon Telescope. 2024. Horizon telescope results for the first Sagittarius A* event. VII. Polarization of the ring. APJL 964, L25; doi: 10.3847/2041-8213/ad2df0

Collaboration with Event Horizon Telescope. 2024. Horizon telescope results for the first Sagittarius A* event. VIII. Physical interpretation of polarization rings. APJL 964, L26; doi: 10.3847/2041-8213/ad2df1

Source: www.sci.news

Astronomers Uncover Two Ancient Substructures within the Milky Way

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The newly identified structures, called Shakti and Shiva, are between 12 billion and 1 billion years old, making them so old that they are even older than the spiral arms and oldest parts of the present-day Milky Way galaxy's disk. may have been formed before.

This image shows the location and distribution of Shakti (yellow) and Shiva (blue) stars throughout the Milky Way. Image credit: ESA / Gaia / DPAC / K. Malhan.

“What's really amazing is that we can detect these ancient structures at all,” said Dr. Kati Malhan, an astronomer at the Max Planck Institute for Astronomy.

“The Milky Way has changed so much since these stars were born that we didn't expect to be able to see them so clearly as a group. But the unprecedented data obtained from ESA's Gaia satellite Thanks to you, this is possible.”

Using Gaia observations, Dr. Mulhan and Dr. Hans-Walter Rix of the Max Planck Institute for Astronomy were able to determine the orbits of individual stars in the Milky Way, as well as their content and composition.

“When we visualized the orbits of all these stars, we found that two new structures stood out from the rest among stars of certain chemical compositions. We named them Shakti and Shiva. '' said Cati.

Each stream contains the mass of about 10 million suns, and the stars, all 12 to 13 billion years old, have similar compositions and move in very similar orbits.

The way they are distributed suggests that they may have formed as separate pieces that merged with the Milky Way early in their lives.

Shakti and Shiva both lie towards the center of the Milky Way.

Gaia explored this part of the Milky Way in 2022 using a type of galactic archaeology. This indicates that this region is filled with the oldest stars in the entire galaxy, all of which were born before the Milky Way disk was properly formed.

“The stars there are so old that they lack many of the heavy metal elements that were created later in the life of the universe,” Dr. Ricks says.

“Because the stars at the center of our galaxy are metal-poor, we named this region the 'poor old heart' of the Milky Way.”

“Until now, we were only aware of very early fragments that came together to form the ancient core of the Milky Way.”

“In Shakti and Shiva we see the first works that appear to be relatively ancient but are located further out.”

“These represent the first steps in the galaxy's growth towards its current size.”

The two streams are very similar, but not identical. The star Shakti orbits a little farther from the center of the Milky Way galaxy and has a more circular orbit than the star Shiva.

Fittingly, these streams are named after the divine couple in Hindu philosophy who come together to create the universe.

About 12 billion years ago, the Milky Way was very different from the orderly spiral we see today.

They believe that our galaxy was formed by the merging of multiple long, irregular filaments of gas and dust that all formed stars and intertwined, giving rise to the galaxy as we know it. It is being

Shaki and Shiva appear to be two of these components, and future Gaia data releases may reveal more.

The authors also created a dynamic map of other known components that play a role in galaxy formation and were discovered using Gaia data.

These include Gaia-Sausage-Enceladus, LMS1/Wukong, Arjuna/Sequoia/I'itoi, and Pontus.

These groups of stars all form part of the Milky Way's complex genealogy that Gaia has been working to build over the past decade.

Dr Timo Prusti, ESA astronomer and Gaia project scientist, said: “Learning more about the early life of the Milky Way is one of Gaia's goals, and we are well on our way to achieving it.”

“To understand how our galaxy formed and evolved, we need to pinpoint subtle but crucial differences between the Milky Way's stars.”

“This requires incredibly accurate data, and now, thanks to Gaia, we have that data.”

“As we discover surprising parts of our galaxy, such as the Shiva and Shakti rivers, we are filling in the gaps and painting a complete picture not just of our current homeland, but of the earliest history of the universe.”

of study Published in astrophysical journal.

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Catty Mulhan & Hans-Walter Ricks. 2024. Shiva and Shakti: A fragment of a primordial galaxy presumed to be inside the Milky Way. APJ 964, 104; doi: 10.3847/1538-4357/ad1885

Source: www.sci.news

Astronomers find hundreds of massive gas clouds streaming away from the Milky Way’s center

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Using new 21 cm radio observations made with NSF's Green Bank Telescope, astronomers have discovered that more than 250 clouds of neutral gas are blasting out into interstellar space from the center of the Milky Way. These clouds are likely the product of the same phenomenon that created the Fermi bubble.

The artist's concept is that clouds flowing from the center of the Milky Way are caught up in extremely hot winds and accelerated to speeds of hundreds of kilometers per second. Image credit: NSF/GBO/P. Vosteen.

It has long been known that energetic processes at the center of the Milky Way generate high-velocity hot winds that spread through intergalactic space with temperatures of millions of degrees and speeds of thousands of kilometers per second. Most large galaxies have winds like this.

The serendipitous discovery that some of this hot gas is trapped in cold hydrogen clouds was made by Australia's ATCA telescope, which measured 21cm radio emissions from interstellar hydrogen atoms.

This suggests that there may be an undiscovered population of clouds transporting material away from the Milky Way's core.

Hydrogen clouds are important in their own right, but they also act as probes for hot air.

Conditions in very hot winds are difficult to measure, but just as a few leaves thrown up on Earth indicate the direction and speed of the wind in the area, cold clouds can You can track its status.

The sensitivity of the Green Bank Telescope (GBT) makes it an ideal instrument for detecting faint signals from interstellar hydrogen, but mapping these clouds and understanding their true extent is essential. It wasn't easy.

Dr Felix James 'Jay' Rockman, senior astronomer at Green Bank Observatory, said: 'It took many years to systematically map hundreds of square degrees using GBT in search of weak hydrogen emissions. ” he said.

“Once we identify a few promising candidates, we can follow up with targeted observations with other telescopes to show us even more.”

“This cloud must have been ripped off from a region near the center of the Milky Way galaxy and flung outward by a burst of star formation or black hole activity.”

Some of these clouds have the fastest outflow velocities of any cloud ever observed in the Milky Way, and may even escape from the Milky Way.

In an unexpected development, new data from the APEX telescope reveals that some hydrogen clouds contain molecules and dense cold gas.

“No one would have expected that the clouds violently ejected from the Milky Way would harbor relatively fragile molecular material, but that's what happened,” Rockman said.

Astronomers using the MeerKAT array recently mapped hydrogen in several clouds with high angular resolution, showing that it evolves and gets shredded as it flows into interstellar space.

“These new results open the door to further discoveries,” Dr. Rockman said.

“How clouds that are accelerated to speeds of more than 400 kilometers per second remain stable is a mystery.”

“The chemical processes inside these clouds are very unusual and unexplored.”

Dr. Rockman and his colleague Dr. Enrico Di Teodoro of the University of Florence, findings in AAS243243rd Meeting of the American Astronomical Society, New Orleans, Louisiana, USA.

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Felix Rockman and Enrico di Teodoro. 2024. New investigation of neutral clouds in the Milky Way's core wind. AAS243Abstract #2851

Source: www.sci.news

New Study Reveals the Superfast Spin of the Milky Way’s Supermassive Black Hole

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Sagittarius A*, the 4.3 million solar mass black hole at the center of the Milky Way, spins so fast that space-time around it is warped into the shape of a soccer ball, according to an analysis. Data collected by NASA's Chandra X-ray Observatory and NSF's Carl G. Jansky Very Large Array.

daily other. Sagittarius A* was found to be rotating at 60% of its maximum rotational speed, which is set by matter that cannot travel faster than the speed of light. This image shows Sagittarius A* in X-ray light from NASA's Chandra X-ray Observatory. Image credit: NASA / CXC / University of Wisconsin / Bai other.

Black holes have two fundamental properties: mass (weight) and spin (rotational speed).

Determining either of these two values ​​can tell astrophysicists a lot about black holes and their behavior.

Dr. Ruth Daly of Pennsylvania State University and colleagues applied a new method using X-ray and radio data to predict Sagittarius A*'s rotation rate based on how matter moves toward or away from the black hole. Decided.

They discovered that Sagittarius A* rotates at an angular velocity (rotations per second). Its angular velocity is about 60% of its maximum possible value, a limit set by the inability of matter to travel faster than the speed of light.

In the past, different astronomers have used different techniques to estimate the rate of rotation of Sagittarius A*, ranging from not rotating at all to rotating at near maximum speed, with mixed results.

“Our research may help answer the question of how fast our galaxy's supermassive black holes rotate,” said Dr. Daly.

“Our results show that Sagittarius A* is rotating very rapidly, which is interesting and has far-reaching implications.”

A rotating black hole pulls space-time and nearby matter into its surroundings as it rotates. Spacetime around a rotating black hole is also crushed.

If you look down at a black hole from above and follow the barrel of the jet it produces, spacetime is circular.

However, if you look at a rotating black hole from the side, spacetime looks like a soccer ball. The faster the spin, the flatter the football.

The spin of a black hole acts as an important source of energy. When a supermassive black hole rotates, its spin energy can be extracted to produce a parallel outflow, a thin beam of matter such as a jet, but this requires at least some material near the black hole. must exist.

Because of the limited fuel surrounding Sagittarius A*, the black hole has been relatively quiet for the last several thousand years, with a relatively weak jet stream.

But new research shows that this could change as the amount of material increases near Sagittarius A*.

“A collimated jet powered by a galaxy's rotating central black hole could have a significant impact on the galaxy's entire gas supply,” said Michigan State University astronomer Megan Donahue. “This also influences the rate and uniformity with which stars form.”

“Fermi bubbles seen in X-rays and gamma rays around the Milky Way's black hole indicate that the black hole was probably active in the past. Measuring the black hole's rotation is important in this scenario. It's a test.”

To determine Sagittarius A*'s spin, astronomers looked at the black hole's spin and its mass, the nature of the matter near the black hole, and its outflow properties.

The parallel outflow produces radio waves, and the disk of gas surrounding the black hole is responsible for emitting X-rays.

Using this method, the researchers combined data from NASA's Chandra X-ray Observatory and NSF's Carl G. Jansky Very Large Array with independent estimates of the black hole's mass from other telescopes. to limit the rotation of the black hole.

“Sagittarius A* offers a special perspective because it is the closest supermassive black hole to us,” said Dr. Anand Lu, an astronomer at McGill University.

“Although it is quiet now, our research shows that in the future it will have an incredibly powerful impact on the matter around it.”

“It could happen in a thousand or million years, or it could happen in our lifetime.”

of study Published in Royal Astronomical Society Monthly Notices.

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Ruth A. Daly et al. 2024. New black hole spin values ​​for Sagittarius A* obtained using the outflow method. MNRAS 527 (1): 428-436; doi: 10.1093/mnras/stad3228

Source: www.sci.news

Three new young stars found in the central region of the Milky Way galaxy by astronomers

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According to some researchers, the oldest of these stars is 1.5 billion years old, while the youngest is only 100 million years old. paper Published in Astrophysics Journal Letter.

This infrared image from Hubble shows the Milky Way Core Cluster, the densest and most massive star cluster in our galaxy. Image credit: NASA / ESA / Hubble Heritage Team / STScI / AURA / T. Do & A. Ghez, UCLA / V. Bajaj, STScI.

The center of our Milky Way galaxy is located about 27,000 light-years away in the constellation Sagittarius and is a crowded place.

This region is so dense that it’s equivalent to a million stars crammed into the space between the Sun and Alpha Centauri, 4.3 light-years away.

This nuclear cluster surrounds Sagittarius A*, a 4.3 million solar mass black hole at the center of the galaxy.

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In general, many nuclear star clusters coexist with supermassive black holes, which are found in more than 70% of galaxies with masses greater than 100 million to 10 billion solar masses.

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“In previous work, we hypothesized that these particular stars in the middle of the Milky Way may be unusually young,” said Lund University astronomer Rebecca Forsberg.

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“Now we can confirm this. Our study shows that three of these stars are relatively young, at least as far as astronomers are concerned, ranging in age from 100 million years to about 1 billion years. We were able to determine the age.”

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“This is equivalent to the age of the Sun, which is 4.6 billion years old.”

This panorama shows the central region of the Milky Way galaxy. It builds on previous surveys by NASA’s Chandra X-ray Observatory and other telescopes, and extends Chandra’s high-energy field of view further up and down the galactic plane than previous imaging campaigns. The X-rays from Chandra are orange, green, and violet, indicating different X-ray energies. Radio data from MeerKAT is gray. Image credits: NASA / CXC / UMass / QD Wang / NRF / SARAO / MeerKAT.

In this study, Dr. Forsberg and colleagues used high-resolution data from the Keck II telescope in Hawaii. This Keck II telescope is one of the largest telescopes in the world with a 10 meter diameter mirror.

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For further verification, they measured the amount of iron, a heavy element, in the stars

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This element is important in tracking the development of galaxies. This is because astronomers’ theories about star formation and galaxy development show that the formation of heavy elements increases over time in the Universe, so younger stars contain more heavy elements.

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To determine iron levels, astronomers looked at the star’s spectrum in infrared light. Infrared light is a part of the light spectrum that can more easily illuminate dust-dense parts of the Milky Way compared to optical light.

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Researchers say there is considerable variation in iron levels.

“The very wide spread in iron levels could indicate that the innermost parts of the galaxy are incredibly heterogeneous, or unmixed,” said Dr. Brian Thorsbro, an astronomer at Lund University. Stated.

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“This is something we didn’t expect, and it tells us something not only about what the center of a galaxy looks like, but also about what the early universe looked like.”

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“Personally, I think it’s very exciting that we can now study the galactic center itself at such a detailed level,” Dr. Forsberg said.

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“While these types of measurements have been standard for observations of our own galactic disk, they have been an unattainable goal in more remote and exotic parts of the galaxy.”

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“Studies like this can teach us a lot about how our home galaxy formed and developed.”

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B. Thorsbro other. 2023. The range of old metallicities of stars in nuclear clusters is wide. APJL 958, L18; doi: 10.3847/2041-8213/ad08b1

Source: www.sci.news