Tag Archives: cosmological

Revolutionary Cosmological Simulations Illuminate Black Hole Growth in the Early Universe

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Revolutionary simulations from Maynooth University astronomers reveal that, at the onset of the dense and turbulent universe, “light seed” black holes could swiftly consume matter, rivaling the supermassive black holes found at the centers of early galaxies.

Computer visualization of a baby black hole growing in an early universe galaxy. Image credit: Maynooth University.

Dr. Daksar Mehta, a candidate at Maynooth University, stated: “Our findings indicate that the chaotic environment of the early universe spawned smaller black holes that underwent a feeding frenzy, consuming surrounding matter and eventually evolving into the supermassive black holes observed today.”

“Through advanced computer simulations, we illustrate that the first-generation black holes, created mere hundreds of millions of years after the Big Bang, expanded at astonishing rates, reaching sizes up to tens of thousands of times that of the Sun.”

Dr. Louis Prowl, a postdoctoral researcher at Maynooth University, added: “This groundbreaking revelation addresses one of astronomy’s most perplexing mysteries.”

“It explains how black holes formed in the early universe could quickly attain supermassive sizes, as confirmed by observations from NASA/ESA/CSA’s James Webb Space Telescope.”

The dense, gas-rich environments of early galaxies facilitated brief episodes of “super-Eddington accretion,” a phenomenon where black holes consume matter at a rate faster than the norm.

Despite this rapid consumption, the black holes continue to devour material effectively.

The results uncover a pivotal “missing link” between the first stars and the immense black holes that emerged later on.

Mehta elaborated: “These smaller black holes were previously considered too insignificant to develop into the gigantic black holes at the centers of early galaxies.”

“What we have demonstrated is that, although these nascent black holes are small, they can grow surprisingly quickly under the right atmospheric conditions.”

There are two classifications of black holes: “heavy seed” and “light seed.”

Light seed black holes start with a mass of only a few hundred solar masses and must grow significantly to transform into supermassive entities, millions of times the mass of the Sun.

Conversely, heavy seed black holes begin life with masses reaching up to 100,000 times that of the Sun.

Previously, many astronomers believed that only heavy seed types could account for the existence of supermassive black holes seen at the hearts of large galaxies.

Dr. John Regan, an astronomer at Maynooth University, remarked: “The situation is now more uncertain.”

“Heavy seeds may be rare and depend on unique conditions for formation.”

“Our simulations indicate that ‘garden-type’ stellar-mass black holes have the potential to grow at extreme rates during the early universe.”

This research not only reshapes our understanding of black hole origins but also underscores the significance of high-resolution simulations in uncovering the universe’s fundamental secrets.

“The early universe was far more chaotic and turbulent than previously anticipated, and the population of supermassive black holes is also more extensive than we thought,” Dr. Regan commented.

The findings hold relevance for the ESA/NASA Laser Interferometer Space Antenna (LISA) mission, set to launch in 2035.

Dr. Regan added, “Future gravitational wave observations from this mission may detect mergers of these small, rapidly growing baby black holes.”

For further insights, refer to this paper, published in this week’s edition of Nature Astronomy.

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D.H. Meter et al. Growth of light seed black holes in the early universe. Nat Astron published online on January 21, 2026. doi: 10.1038/s41550-025-02767-5

Source: www.sci.news

How “Beauty Factory” Addresses Two Major Cosmological Mysteries

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“B-mesons assist us in unraveling significant cosmic queries. Why is there a predominance of matter over antimatter?”

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Did you know that in the realm of physics, there are facilities dubbed beauty factories? This term doesn’t refer to aesthetics; rather, it describes an experiment where electrons collide with their antimatter equivalents, positrons, to create B-mesons.

B-mesons are constructed from quarks, the building blocks of normal matter. Typically, everyday matter comprises up-quarks and down-quarks, while B-mesons are made up of beauty quarks combined with up, down, charm, or strange quarks.

This unique configuration results in B-mesons having a fleeting existence, seemingly detached from common life. However, their significance lies in the potential answers they hold regarding universal enigmas, such as the imbalance of matter versus antimatter.

We understand that all particles have corresponding antiparticles. Yet, when we observe the universe, we see a predominance of particles, like electrons, overshadowing their antiparticle counterparts, positrons, which are merely identical but with reversed charges.

Mesons are particularly intriguing as they inhabit the space between the prevalent matter and antimatter realms. This positions them as potential keys to unlocking the mystery of the disparity between the two. Grasping this could clarify why the universe holds such a favorable balance of matter when encounters between matter and antimatter typically result in annihilation. The formation of B factories arises from the desire to decode this cosmic puzzle.

The complexity deepens when considering mesons and their own antiparticles. Each B-meson consists of beauty quarks paired with up, down, charm, or strange quarks. Neutral B-mesons, devoid of charge, exhibit oscillatory behavior as they transform between mesons and their antiparticles. In essence, neutral B-mesons exemplify a spontaneous non-binary state.

These neutral B-mesons are pivotal in addressing the asymmetry of matter and antimatter. Their non-binary characteristics are anticipated within the standard model of particle physics, which catalogs known particles. However, we must determine whether these oscillatory states are evenly distributed. Are collisions more likely to yield a meson or its antiparticle? Disparities in these oscillations may shed light on the core asymmetries of matter and antimatter.

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B factories could illuminate the nature of an elusive component: dark matter, which remains unseen in laboratories.
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In 2010, researchers from the Fermilab Dzero collaboration identified a 1% deviation, although subsequent studies haven’t corroborated this result. The exploration of these discrepancies continues to intrigue, particularly as variances emerge in unrelated vibration studies.

B factories may also expand our comprehension of dark matter, an entity detected only through its gravitational effects on visible matter. Approximately 85% of the universe’s mass seems to consist of this invisible material, which the standard model has yet to account for.

Crafting a theory to explain dark matter necessitates postulating new particles or forces, some of which might interact subtly with known particles, complicating detection. These interactions often hinge on mediators—entities that facilitate such connections. While these mediators are elusive, under optimal conditions, they may not be directly observable. However, we can anticipate witnessing decay products, such as electron-positron pairs, serving as indicators. This is where B factories play a crucial role; they are engineered to analyze the outcomes of electron-positron collisions.

In addition to collider physics, the longevity of data acquisition and experiments is particularly captivating. For instance, the BABAR experiment at the SLAC National Accelerator Laboratory closed in 2008, yet researchers continue to sift through its data, educating the next generation of physicists.

In 2022, Brian Schub and his undergraduate team at Harvey Mudd College near Los Angeles revisited ideas involving nearly two-decade-old BABAR data. They proposed that virtual particles, referred to as axions, may function as mediators between visible and dark matter. Long-time readers may recognize that axion research is a focal point of my work.

So, do these hypotheses regarding our universe’ mechanics hold water? This inquiry aligns with our quest to comprehend matter-antimatter asymmetry.

What I’m reading

I’ve just finished Wasim, a student of Gazan physics. Witness to the Hellfire of Genocide, A tragic memoir.

What I’m watching

I’m finally watching The Wire after years of avoidance.

What I’m working on

I am reexamining cosmological perturbation theory.

Chanda Prescod-Weinstein is an associate professor of physics and astronomy at the University of New Hampshire. She is the author of The Disordered Cosmos and future works Edges of Space Time: Particles, Poetry, Boogie in the Universe Dreams

Source: www.newscientist.com

Astronomers Use Cosmological Radio Signals to Identify First-Generation Stars in the Universe

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The primordial stars, known as group III, likely formed from the abundant gases present in the young universe. These stars were responsible for generating the first heavier elements, illuminating the universe, bringing an end to the cosmic dark ages, and ushering in the era of reionization. Due to the challenges of direct observation, the characteristics of these early stars are still largely unknown. Professor Anastasia Fialkov from Cambridge University and her team suggest that astronomers can infer the masses of these stars by analyzing the cosmological 21 cm signal produced by hydrogen atoms located between the regions where the stars formed.

Artist’s impression of a field of Population III stars that would have existed hundreds of millions of years post-Big Bang. Image credits: noirlab/nsf/aura/J. da silva/SpaceEngine.

“This presents a unique opportunity to understand how the universe’s first light emerged from darkness,” stated Professor Fialkov.

“We are beginning to unravel the narrative of the transition from a cold, dark cosmos to one filled with stars.”

Studies focused on the universe’s ancient stars rely on the faint 21 cm signal, an energy signature emanating from over 13 billion years ago.

This signal, influenced by the radiation from nascent stars and black holes, offers a rare glimpse into the universe’s formative years.

Professor Fialkov leads the Leach theory group dedicated to radio experiments analyzing space hydrogen.

“Leach is a radio antenna and one of two key projects designed to enhance our understanding of the dawn and reionization phases of the universe, when the first stars reactivated neutral hydrogen atoms,” explained the astronomer.

“While our abilities to capture radio signals are presently undergoing calibration, we remain dedicated to unveiling insights about the early universe.

“Conversely, the Square Kilometer Arrays (SKAs) chart variations in cosmic signals across extensive areas of the sky.”

“Both initiatives are crucial for probing the masses, brightness, and distribution of the universe’s earliest stars.”

In their current research, Professor Fialkov and co-authors formulated a model to predict the 21 cm signal for both REACH and SKA, discovering that the signal is sensitive to the mass of the first stars.

“We are the first group to accurately model how the 21 cm signal correlates with the mass of the first stars, factoring in ultraviolet starlight and x-ray emissions resulting from the demise of the first stars,” stated Professor Fialkov.

“Our findings stem from simulations integrating the primordial conditions of the universe, such as the hydrogen and helium composition formed during the Big Bang.”

In developing their theoretical framework, researchers examined how the 21 cm signal responds to the mass distribution of Population III stars.

They discovered that earlier studies underestimated this relationship as they failed to account for both the quantity and luminosity of x-ray binaries among Population III stars and their impact on the 21 cm signal.

While REACH and SKA cannot photograph individual stars, they do provide comprehensive data on stars, x-ray binary systems, and entire galactic populations.

“Connecting radio data to the narrative of the first stars requires some imagination, but its implications are profound,” remarked Professor Fialkov.

“The predictions we present hold significant value in enhancing our understanding of the universe’s earliest stars,” noted Dr. Eloi de Lera Acedo from Cambridge University.

“We offer insights into the masses of these early stars, suggesting that the light they emitted may have been drastically different from today’s stars.”

“Next-generation telescopes like REACH are set to unlock the secrets of the early universe. These predictions are vital for interpreting radio observations being conducted from Karu, South Africa.”

The research paper was published online today in the journal Nature Astronomy.

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T. Gessey-Jones et al. Determination of the mass distribution of the first stars from a 21 cm signal. Nature Astronomy Published online on June 20th, 2025. doi:10.1038/s41550-025-02575-x

Source: www.sci.news