Researchers find that fluctuations in the kinetic energy of the expanding universe are often mistaken for dark energy

Dark energy, the unknown energy source accelerating the expansion of the universe, doesn't actually exist, according to a new study.

This artist's impression shows the evolution of the universe, starting with the Big Bang on the left and continuing with the emergence of the Cosmic Microwave Background. The formation of the first stars ends the Dark Ages of the universe, followed by the formation of galaxies. Image credit: M. Weiss / Harvard-Smithsonian Center for Astrophysics.

Dark energy is generally thought to be a weak antigravity that acts independently of matter and accounts for about two-thirds of the mass-energy density of the universe.

The lambda cold dark matter (ΛCDM) model, which has served as the standard cosmological model for a quarter of a century, requires dark energy to explain the observed acceleration in the expansion rate of the universe.

Astrophysicists base this conclusion on measurements of distances to supernova explosions in distant galaxies, which appear to be farther away than they should be if the expansion of the universe is not accelerating.

However, the current expansion rate of the universe is increasingly being questioned by new observations.

First, evidence from the Big Bang's afterglow (cosmic microwave background radiation) shows that the expansion of the early Universe is inconsistent with the current expansion, an anomaly known as the Hubble tension.

Furthermore, in an analysis of new high-precision data from the Dark Energy Spectrometer (DESI), the scientists showed that the ΛCDM model does not fit a model in which dark energy does not remain constant but evolves over time. I discovered it.

Both the Hubble tension and the surprises revealed by DESI are difficult to resolve with models that use the simplistic expansion law of the universe from 100 years ago, or the Friedman equation.

This assumes that the universe expands uniformly on average. It's as if you could put all the cosmic structures in a blender and make a nondescript soup without complex structures.

But the current universe actually contains a complex cosmic web of galaxy clusters of sheets and filaments that surround and thread a vast void.

“Our findings show that dark energy is not needed to explain why the universe appears to be expanding at an accelerating rate,” said Professor David Wiltshire.

“Dark energy is a misidentification of fluctuations in the kinetic energy of expansion, which is not uniform in the blocky universe we actually live in.”

“This study provides compelling evidence that may answer some of the key questions about the quirks of our expanding universe.”

“With new data, the universe's greatest mysteries could be solved by the end of the decade.”

New evidence supports the timescape model of the expansion of the universe, which says dark energy is not needed because the difference in the stretch of light is not a result of the universe's acceleration, but of how it adjusts time and distance. .

An ideal clock in empty space would tick faster than in a galaxy, since gravity slows time down.

This model suggests that the Milky Way's clock is about 35% slower than the same clock at its average location in the large cosmic void. That means billions more years have passed in the void.

This allows for further expansion of the universe, and as such a vast void grows to dominate the universe, it appears to be expanding faster and faster.

“We now have so much data that only in the 21st century can we begin to answer the question of how and why a simple mean expansion law emerges from complexity. ” said Professor Wiltshire.

“A simple law of expansion consistent with Einstein's theory of general relativity does not need to obey Friedman's equation.”

“ESA's Euclid satellite, launched in July 2023, has the ability to test and differentiate the Friedman equation from timescape alternatives.”

“However, this will require at least 1,000 independent high-quality supernova observations.”

of study Published in Monthly Notices of the Royal Astronomical Society: Letters.

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antonia seifert others. 2025. Supernovae are evidence of fundamental changes in cosmological models. MNRASL 537 (1): L55-L60;doi: 10.1093/mnrasl/slae112

Source: www.sci.news

Astronomers reveal new main-belt comet mistaken for active asteroid

456P/Panstars, an active main-belt asteroid first discovered in 2021, is repeatedly active, and its activity is linked to volatile ice formations, according to new observations from the Magellan-Baade and Lowell Discovery telescopes. It is likely that this is caused by sublimation.



456P/PanSTARS image taken on October 3, 2024 with the Magellan Baade Telescope in Chile and with the Lowell Discovery Telescope in Arizona on October 26, 2024. At the center of each image is the comet’s head or nucleus, the tail extends to the right. Image credits: Scott S. Sheppard / Carnegie Institution for Science / Audrey Thirouin, Lowell Observatory / Henry H. Hsieh, Planetary Science Institute.

“Main-belt comets are icy objects found in the asteroid belt between Mars and Jupiter, rather than outside the cold solar system, where icy objects would normally be expected,” said Henry Hsieh, senior scientist at the Planetary Science Institute.

“They have comet-like features, such as tails that extend away from the sun and fuzzy clouds as the sun’s heat evaporates the ice.”

These objects were first discovered in 2006 at the University of Hawaii by Dr. Hsieh and his then-doctoral supervisor, Professor David Jewitt.

“Main-belt comets belong to a larger group of Solar System objects known as active asteroids, which look like comets but have asteroid-like orbits in the warm inner Solar System,” the astronomers said.

“This large group includes not only objects that emit dust from evaporated ice, but also objects that have clouds or tails of ejected dust from collisions or rapid rotation.”

“Both main-belt comets and active asteroids in general are still relatively rare, but scientists are discovering them.”

456P/PANSTARRS was discovered as P/2021 L4 (PANSTARRS) through observations by Pan-STARRS1 on June 9 and 14, 2021, and observations by Canada, France, and Hawaii telescopes on June 14, 2021.

Dr. Hsieh and his co-authors observed the object twice in October 2024 using the Magellan-Baade Telescope and the Lowell Discovery Telescope, establishing its status as a main-belt comet.

“This object is not just an asteroid that experienced a one-off event, but is essentially an active icy object, like other comets in the outer solar system,” Hsieh said.

If 456P/PANSTARRS’s activity is due to something other than ice evaporation, its tail would be expected to appear only once, randomly, and not repeatedly as it approaches the Sun.

On the other hand, icy objects heat up every time they approach the sun, and the evaporated ice is carried away with the dust.

As the object moves away from the sun and cools, it ceases to be active.

Observations of repeated dust ejection activity during their approach to the Sun are currently considered the best and most reliable method of identifying main-belt comets.

“Confirmed main-belt comets are still largely unknown,” Dr. Xie said.

“We want to grow the population so we can understand more clearly what its broader characteristics are, such as its size, active period, and distribution within the asteroid belt. We will be able to better utilize them to track ice within the asteroid belt and across the solar system.”

of findings Published in American Astronomical Society Research Notes.

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Henry H. Shea others. 2024. Recurrence activity of main belt comet 456P/Panstars (P/2021 L4) confirmed. Resolution memo AAS 8,283;doi: 10.3847/2515-5172/ad90a6

This article is a reprint of a press release provided by the Planetary Science Institute.

Source: www.sci.news

The Webb’s ERO-BluDOG Mix-Up: A Space Incident of Mistaken Identity

Researchers re-evaluated extremely red objects (EROs) in the JWST data and found similarities with BluDOGs previously identified from Subaru Telescope data. This discovery contributes to a broader understanding of quasar evolution and points to the need for further research using advanced telescopes like GREX-PLUS. Credit: SciTechDaily.com

Space researchers have discovered that extremely red objects (EROs) exist in space. james webb space telescope This data is similar to the Subaru Telescope’s BluDOG, challenging previous assumptions and highlighting the complexity of studying quasar evolution.

Not every discovery is actually a new discovery. This is the case for extremely red objects (EROs) found in the James Webb Space Telescope (JWST) data. The analysis showed that it is very similar to a blue-excessive dust-covered galaxy (BluDOG) previously reported using data from the Subaru Telescope.

Quasars, some of the brightest objects in the universe, are powered by supermassive black holes with masses that can reach more than a billion times that of the Sun. Although these objects are the focus of much research, how they form is still poorly understood. A leading theory is that quasars form within galaxies with clouds of gas and dust that obscure the growing quasar until they become powerful enough to blow away the clouds. If this is true, we should be able to catch a short window of time when a quasar breaks out of the cloud.

A galaxy covered in blue excess dust (BluDOG) photographed by the Subaru Telescope.Credit: National Astronomical Observatory of Japan/HSC cooperation

Because the transition period is short, we must observe a large number of prequasar candidates and hope that we are lucky enough to catch a galaxy just as the quasar begins to erupt. Examining the JWST data, a group of extremely red objects (EROs) were identified as possible transitional quasars. But researchers at the Subaru telescope, a Japanese telescope in Hawaii, say that although ERO is called “red,” it is similar to the blue-excess dust-encrusted galaxy (BluDOG) found in big data. I noticed that it also has an important blue component. It was obtained from the Subaru Telescope and described in last year’s report.

Our analysis shows that ERO and BluDOG are likely objects of the same class, but that there are also important differences. One possibility is that ERO is at an earlier stage of evolution than BluDOG. More candidate samples need to be collected to determine the true relationship between ERO, BluDOG, and quasars. Larger samples will be studied by next-generation astronomical instruments, including a planned infrared space telescope project in Japan called GREX-PLUS.

References:

“Similarities between the compact, very red object discovered by JWST at the dawn of the universe and the blue, dust-covered galaxy known at the noon of the universe” Akatoki Noboriguchi, Akio Inoue, Toru Nagao, Yoshiki Toba, Toru Misawa, December 14, 2023 of Astrophysics Journal Letter.
DOI: 10.3847/2041-8213/ad0e00

“The extreme properties of four blue dust-covered galaxies revealed by optical spectroscopy” Akatoki Noboriguchi, Toru Nagao, Yoshiki Toba, Kohei Ichikawa, Masaru Kajisawa, Nanako Kato, Toshihiro Kawaguchi, Hideo Matsubara , Yoshiki Matsuoka, Kyoko Onishi, Masafusa Onoe, Nozomu Tamada, Koki Terao, Yuichi Terashima, Yoshihiro Ueda, Takuji Yamashita, December 23, 2022, of astrophysical journal.
DOI: 10.3847/1538-4357/aca403

“Optical properties of galaxies covered with infrared bright dust seen with Subaru Hyper Supreme Cam” Akatoki Noboriguchi, Toru Nagao, Yoshiki Toba, Mana Niida, Masaru Kajisawa, Masafusa Onoe, Yoshiki Matsuoka, Takuji Yamashita, Yuyan Zhang , Toshihiro Kawaguchi, Yutaka Komiyama, Kodai Nobehara, Yuichi Terashima, Yoshihiro Ueda, May 13, 2019, astrophysical journal.
DOI: 10.3847/1538-4357/ab1754

Source: scitechdaily.com