Dark matter could explain earliest supermassive black holes

Dark matter decays could be the missing ingredient explaining how giant black holes formed before the first stars
Image Credit: Scientific Frontline

Scientific Frontline: Extended "At a Glance" Summary: Decaying Dark Matter and Early Supermassive Black Holes

The Core Concept: The decay of dark matter particles in the early universe may have released sufficient energy to alter the chemistry of primordial gas clouds, causing them to collapse directly into supermassive black holes instead of forming stars.

Key Distinction/Mechanism: Standard astrophysical models suggest black holes form from the collapse of individual stars and grow slowly over time, a timeline that cannot account for the massive scale of the earliest known black holes. This new mechanism posits that decaying dark matter particles (specifically axions) inject trace amounts of energy into pristine hydrogen gas, supercharging the direct collapse rate without requiring the historically assumed, and statistically rare, presence of nearby stellar radiation.

Major Frameworks/Components:

• Direct Collapse Black Holes (DCBH): A theoretical pathway where massive clouds of primordial gas bypass the star-formation phase and collapse directly into a black hole.
• Axion Dark Matter Decay: A specific dark matter model utilizing particles with masses between 24 and 27 electronvolts, which release billion-trillionths of an energy unit upon decay.
• Thermo-Chemical Dynamics: The analysis of how microscopic energy injections from dark matter alter the thermodynamic evolution and cooling processes of pristine hydrogen gas.

New simulations reveal the cold, dusty reality of galaxy formation

Visual impression of the dynamic range in the high-resolution COLIBRE simulation L025m5 at redshift z = 0.1. The top left panel shows a projection of the entire simulation with the colour encoding baryon surface density. The other panels zoom into different regions and show the stellar light in HST colours accounting for attenuation by dust.
Hi-Res Zoomable Version
Image Credit: Schaye et al. (2026)

Scientific Frontline: Extended "At a Glance" Summary: COLIBRE Cosmological Simulations

The Core Concept: COLIBRE is a groundbreaking set of advanced cosmological simulations that models the evolution of galaxies by integrating cold interstellar gas and cosmic dust, offering the most realistic digital representation of galaxy formation from the early universe to the present day.

Key Distinction/Mechanism: Unlike previous large-scale models that were limited to simulating gas at temperatures of 10,000 Kelvin or higher, COLIBRE directly models the physical and chemical processes of cold gas and microscopic dust grains. Utilizing up to 20 times more resolution elements than earlier frameworks, it accurately reproduces complex real-world observations, including those captured by the James Webb Space Telescope (JWST).

Major Frameworks/Components: 

• Cold Interstellar Gas Modeling: Direct computational simulation of the low-temperature gas where actual stellar formation occurs, overcoming the computational limitations of previous high-temperature models.
• Cosmic Dust Integration: Simulation of dust grains that catalyze the formation of hydrogen molecules, shield gas from harsh ultraviolet radiation, and re-emit absorbed starlight as infrared energy.
• High-Resolution Supercomputing: Execution via the SWIFT simulation code on advanced supercomputer architecture, consuming up to 72 million CPU hours for the largest iterations to generate vast cosmic volumes with high statistical accuracy.
• Standard Cosmological Model Validation: Confirms that the standard theoretical framework of cosmology aligns with observational data once essential localized physical processes (like cold gas and dust) are properly represented.

The Local Universe’s Expansion Rate Is Clearer Than Ever, but Still Doesn’t Add Up

Artist’s interpretation of the cosmic distance ladder — a succession of overlapping methods used to measure distances across the Universe, where each rung of the ladder provides information that can be used to determine the distances at the next higher rung. Methods include observations of pulsating Cepheid variable stars, red giant stars that shine with a known brightness, Type Ia supernovae, and certain types of galaxies.  In this illustration, the distance ladder begins at the Coma Cluster, which is the nearest extremely rich galaxy cluster to us. The distance to the Coma Cluster can be measured directly using observations of Type Ia supernovae within the cluster. Type Ia supernovae have a predictable luminosity that makes them reliable objects for distance calculations. 
Image Credit: CTIO/NOIRLab/DOE/NSF/AURA/J. Pollard

Scientific Frontline: Extended "At a Glance" Summary: The Hubble Tension and the Local Distance Network

The Core Concept: The Hubble tension is a persistent, statistically significant discrepancy between the Universe's expansion rate measured in the local Universe and the rate predicted from the early Universe using the standard model of cosmology.

Key Distinction/Mechanism: Rather than relying on a single measurement method, this breakthrough framework unites decades of independent distance measurements into a unified "distance network." By cross-linking overlapping techniques—such as observing Cepheid variable stars, red giant stars, and Type Ia supernovae—astronomers achieved a local expansion rate of 73.50 ± 0.81 km/s/Mpc with roughly 1% precision. This multi-path approach effectively rules out single-method observational errors as the cause of the discrepancy with the early Universe prediction of 67–68 km/s/Mpc.

Major Frameworks/Components: 

• The Standard Model of Cosmology: The theoretical baseline used to predict the present-day expansion rate based on cosmic microwave background measurements.
• The Cosmic Distance Ladder/Network: An observational methodology utilizing multiple independent, overlapping distance indicators to measure the local Universe.
• H0 Distance Network (H0DN) Collaboration: An international, community-built framework synthesizing independent astrophysical measurements from both ground and space-based observatories, including the NSF NOIRLab programs.

Ghostly particles: Is dark radiation masquerading as neutrinos?

Bhupal Dev / Associate Professor of Physics
Photo Credit: Courtesy of Washington University in St. Louis

Scientific Frontline: Extended "At a Glance" Summary: Dark Radiation and Neutrino Cosmology

The Core Concept: During the earliest moments of the universe, a fraction of neutrinos may have transformed into a previously unknown form of fast-moving light radiation known as "dark radiation." This theoretical conversion offers a novel explanation for cosmological anomalies regarding how the universe evolved and expanded.

Key Distinction/Mechanism: While recent cosmological data suggested that neutrinos might interact with one another more strongly than predicted by the standard model, laboratory experiments place strict limits on such interactions. The newly proposed mechanism resolves this mismatch: rather than neutrinos interacting strongly, the presence of dark radiation mimics the cosmological effects of strongly interacting neutrinos without violating the constraints established by terrestrial physics experiments.

Origin/History: This theoretical framework was published on April 2, 2026, in Physical Review Letters by a research team led by Bhupal Dev at Washington University in St. Louis. The study posits that the transformation into dark radiation must have occurred in a specific chronological window: after Big Bang nucleosynthesis but before the formation of the cosmic microwave background.

Major Frameworks/Components: 

• The Standard Model of Particle Physics: The baseline theoretical framework that accurately predicts weak interactions of standard neutrinos.
• Big Bang Nucleosynthesis: The early universe process during which the first nuclei were formed, serving as the lower temporal bound for the dark radiation conversion.
• Cosmic Microwave Background (CMB): The remnant radiation from the early universe, serving as the upper temporal bound for when this conversion could have taken place.
• The Hubble Tension: The persistent discrepancy between different scientific measurements of the universe's expansion rate, which the dark radiation model attempts to reconcile.

'Space Archaeology' Reveals First Dynamic History of a Giant Spiral Galaxy

An artist's impression shows the giant spiral galaxy NGC 1365 as it collides and merges with a smaller companion galaxy, stirring up star formation and redistributing gas and heavy elements. Using a new "space archaeology" technique that reads the chemical fingerprints in the galaxy’s gas, astronomers have reconstructed how NGC 1365 grew over 12 billion years.
Image Credit: Melissa Weiss/CfA

Scientific Frontline: Extended "At a Glance" Summary: Extragalactic Archaeology and the Evolution of NGC 1365

The Core Concept: Extragalactic archaeology is a novel astronomical technique that reconstructs the multi-billion-year evolutionary history of distant galaxies by analyzing the detailed chemical fingerprints embedded in their gas and star-forming clouds.

Key Distinction/Mechanism: Unlike traditional observations that capture a static snapshot of a galaxy, this method maps the distribution of heavy elements (such as oxygen) across a galaxy's structure using high-resolution spectroscopy. These chemical patterns are then compared against state-of-the-art cosmological simulations to infer the galaxy's historical timeline, including past mergers, gas flows, and star formation rates over cosmic time.

Major Frameworks/Components:

• TYPHOON Survey: An observational initiative utilizing the Irénée du Pont telescope to achieve sharp resolutions of individual star-forming clouds, isolating specific diagnostic emission lines (like ionized hydrogen, nitrogen, and oxygen) across the galaxy's disk.
• Chemical Fingerprinting: The process of analyzing the light emitted by excited gases around young, hot stars to measure the concentration and distribution of heavy elements from the galactic center to the outer spiral arms.
• The Illustris Project: Advanced cosmological simulations that model the physical processes of the universe—such as gas motion, black hole activity, and chemical evolution—used to find a precise theoretical match to the observed data.

Cosmology: In-Depth Description

Cosmology is the scientific study of the origin, evolution, large-scale structures, and eventual fate of the universe as a whole. Its primary goal is to understand the universe in its totality—how it began (most notably through the Big Bang), how it has expanded and developed over billions of years, and the fundamental physical laws that govern its macroscopic behavior. Unlike astronomy, which often focuses on individual celestial objects like stars or galaxies, cosmology examines the universe as a singular, cohesive entity.

Supermassive black holes sit in ‘eye of their own storms,’ studies find

An artist’s rendition of the immediate vicinity around the supermassive black hole known as M87*. However, the roiling, superhot gases around these black holes extend much further than seen in this visualization. Two new studies give us new insight into the regions around these black holes and how they influence their surrounding galaxies.
Illustration Credit: S. Dagnello NRAO/AUI/NSF

Scientific Frontline: "At a Glance" Summary

• Main Discovery: A powerful, rotating magnetic wind has been identified encircling a supermassive black hole, acting as a feeding mechanism that enables the black hole’s growth rather than pushing material away.
• Methodology: Researchers utilized the Atacama Large Millimeter/submillimeter Array (ALMA) to detect and analyze specific light wavelengths from hydrogen cyanide (HCN) molecules, using the Doppler effect to trace the motion and structure of gas hidden behind thick dust layers.
• Key Data: The study focused on the galaxy ESO320-G030, located approximately 120 million light-years from Earth, revealing a wind structure that contradicts previous models of purely repulsive outflows.
• Significance: This discovery solves a persistent mystery in astrophysics regarding how supermassive black holes accrete mass efficiently, demonstrating that magnetic fields can create a "storm" that funnels matter inward rather than expelling it.
• Future Application: Astronomers intend to survey other active galaxies to determine if this magnetic wind phase is a universal stage in the lifecycle of all supermassive black holes.
• Branch of Science: Astrophysics and Cosmology
• Additional Detail: The observed process parallels the mechanics of star formation ("baby stars"), suggesting that similar physical laws govern growth across vastly different cosmic scales, from small suns to galactic monsters.

The infant universe’s “primordial soup” was actually soup

A quark zooms through quark-gluon plasma, creating a wake in the plasma. “Studying how quark wakes bounce back and forth will give us new insights on the quark-gluon plasma’s properties,” Yen-Jie Lee says.
Image Credit: Jose-Luis Olivares, MIT
(CC BY-NC-ND 4.0)

Scientific Frontline: "At a Glance" Summary

• Main Discovery: Researchers have observed the first direct evidence that the "primordial soup" of the early universe—quark-gluon plasma—behaves as a dense, frictionless liquid rather than a gas, indicated by the formation of wakes behind speeding quarks.
• Methodology: The team utilized data from the Compact Muon Solenoid (CMS) experiment at CERN's Large Hadron Collider, where heavy lead ions were smashed together at near-light speeds to briefly recreate the primordial plasma; they then analyzed the trajectories of quark-antiquark pairs to detect specific "sloshing" or wake patterns generated as particles moved through the medium.
• Key Data: The laboratory-created plasma droplets existed for less than a quadrillionth of a second and reached temperatures of several trillion degrees Celsius, mirroring conditions just a few millionths of a second after the Big Bang.
• Significance: This confirmation resolves a longstanding debate in physics, proving that the infant universe's matter functioned as a cohesive fluid that creates ripples and swirls (similar to a boat in water) rather than a system of randomly scattering individual particles.
• Future Application: The novel technique of using quark wakes as probes will allow physicists to measure the viscosity and internal properties of quark-gluon plasma with greater precision, effectively providing a detailed "snapshot" of the universe's earliest moments.
• Branch of Science: High-Energy Particle Physics / Cosmology
• Additional Detail: The study validates the theoretical "hybrid model" which predicted that high-energy jets (quarks) would induce a hydrodynamic response in the plasma, slowing down the particles and generating a detectable wake.

NASA Reveals New Details About Dark Matter’s Influence on the Universe

Created using data from NASAs Webb telescope in 2026 (right) and from the Hubble Space Telescope in 2007 (left), these images show the presence of dark matter in the same region of sky. Webb's higher resolution is providing new insights into how this invisible component influences the distribution of ordinary matter in the universe.
Image Credit:NASA/STScl/A Pagan

Scientific Frontline: Extended "At a Glance" Summary

The Core Concept: A highly detailed map of dark matter distribution created using data from the James Webb Space Telescope (JWST), revealing the invisible "scaffolding" that structures the universe.

Key Distinction/Mechanism: Unlike previous, blurrier maps, this new visualization is twice as sharp and provides empirical confirmation that dark matter and ordinary matter are tightly interlocked. It utilizes gravitational lensing—observing how dark matter's mass warps space and bends light from distant galaxies—to trace invisible structures with unprecedented precision.

Major Frameworks/Components:

• Gravitational Lensing: The primary method used to detect non-luminous dark matter by measuring how it distorts background light.
• Cosmic Evolution Survey (COSMOS): The specific region of the sky (in the constellation Sextans) observed for this study.
• Mid-Infrared Instrument (MIRI): A key JWST instrument used to measure galactic distances and penetrate cosmic dust.
• Matter Correlation: The study confirms a direct spatial overlap between "clumps" of dark matter and clusters of ordinary (baryonic) matter.

Branch of Science: Astrophysics, Cosmology.

Future Application: These detailed maps will help refine models of cosmic evolution, specifically clarifying how early dark matter structures accelerated the formation of the first stars and galaxies, thereby enabling the creation of planetary systems.

Why It Matters: It validates the theory that dark matter acts as the gravitational anchor for the visible universe. By proving that dark matter grew alongside ordinary matter, scientists can better understand the timeline of the universe's development, including the conditions that allowed for the emergence of planets like Earth.

Space Science: In-Depth Description

Image Credit: Scientific Frontline / AI generated (Gemini)

Space Science is the multifaceted scientific discipline dedicated to the exploration and study of natural phenomena and physical bodies occurring beyond Earth's atmosphere. Its primary goals are to understand the origins, evolution, and future of the Universe, to discover the fundamental physical laws governing the cosmos, and to explore the potential for life beyond our planet.

A speed camera for the universe

The stars (or rather galaxies) of the show.
A montage of eight time-delay gravitational lens systems. There’s an entire galaxy at the center of each image, and the bright points in rings around them are gravitationally lensed images of quasars behind the galaxy. These images are false-color and are composites of data from different telescopes and instruments.
Image Credit: ©2025 TDCOSMO Collaboration et al.
(CC BY-ND 4.0)

There is an important and unresolved tension in cosmology regarding the rate at which the universe is expanding, and resolving this could reveal new physics. Astronomers constantly seek new ways to measure this expansion in case there may be unknown errors in data from conventional markers such as supernovae. Recently, researchers including those from the University of Tokyo measured the expansion of the universe using novel techniques and new data from the latest telescopes. Their method exploits the way light from extremely distant objects takes multiple pathways to get to us. Differences in these pathways help improve models on what happens at the largest cosmological scales, including expansion.

After nearly 100 years, scientists may have detected dark matter

Gamma-ray image of the Milky Way halo (with details).
Gamma-ray intensity map excluding components other than the halo, spanning approximately 100 degrees in the direction of the Galactic center. The horizontal gray bar in the central region corresponds to the Galactic plane area, which was excluded from the analysis to avoid strong astrophysical radiation.
 Image Credit: ©2025 Tomonori Totani, The University of Tokyo

In the early 1930s, Swiss astronomer Fritz Zwicky observed galaxies in space moving faster than their mass should allow, prompting him to infer the presence of some invisible scaffolding — dark matter — holding the galaxies together. Nearly 100 years later, NASA’s Fermi Gamma-ray Space Telescope may have provided direct evidence of dark matter, allowing the invisible matter to be “seen” for the very first time.

Dark matter has remained largely a mystery since it was proposed so many years ago. Up to this point, scientists have only been able to indirectly observe dark matter through its effects on observable matter, such as its ability to generate enough gravitational force to hold galaxies together. The reason dark matter can’t be observed directly is because the particles that make up dark matter don’t interact with electromagnetic force — meaning dark matter doesn’t absorb, reflect or emit light.

X-Ray Study Reveals New Details About Betelgeuse’s Elusive Companion Star

Betelbuddy, the companion star to Betelgeuse. This image is a color composite made from exposures from the Digitized Sky Survey 2.
Image Credit: ESO/Digitized Sky Survey 2. Acknowledgment: Davide De Martin

Astronomers have long suspected that Betelgeuse — the bright red star blazing in Orion's shoulder — wasn't alone. Now, thanks to a fleeting cosmic window and swift action by Carnegie Mellon University researchers, the true nature of its elusive companion has been illuminated.

In a race against time, the CMU researchers secured director’s discretionary time on both NASA’s Chandra X-ray Observatory and the Hubble Space Telescope to investigate the long-predicted — but never detected — companion star to Betelgeuse. The timing was critical: Around Dec. 6, the companion, nicknamed “Betelbuddy,” reached its maximum separation from the massive red supergiant just before it would disappear behind it for two more years.

“It turns out that there had never been a good observation where Betelbuddy wasn't behind Betelgeuse,” said Anna O’Grady, a McWilliams Postdoctoral Fellow at Carnegie Mellon’s McWilliams Center for Cosmology and Astrophysics. “This represents the deepest X-ray observations of Betelgeuse to date.”

Discovery of Unexpected Ultramassive Galaxies May Not Rewrite Cosmology, But Still Leaves Questions

Infrared view of the universe captured by the James Webb Space Telescope.
Image Credit: NASA, ESA, CSA and STScI.

Ever since the James Webb Space Telescope (JWST) captured its first glimpse of the early universe, astronomers have been surprised by the presence of what appear to be more “ultramassive” galaxies than expected. Based on the most widely accepted cosmological model, they should not have been able to evolve until much later in the history of the universe, spurring claims that the model needs to be changed.

This would upend decades of established science.

“The development of objects in the universe is hierarchical. You start small and get bigger and bigger,” said Julian Muñoz, an assistant professor of astronomy at The University of Texas at Austin and co-author of a recent paper that tests changes to the cosmological model. The study concludes that revising the standard cosmological model is not necessary. However, astronomers may have to revisit what they understand about how the first galaxies formed and evolved.

Cosmology studies the origin, evolution and structure of our universe, from the Big Bang to the present day. The most widely accepted model of cosmology is called the Lambda Cold Dark Matter (ΛCDM) model or the “standard cosmological model.” Although the model is very well informed, much about the early universe has remained theoretical because astronomers could not observe it completely, if at all.

Astronomers detect most distant fast radio burst to date

This artist’s impression (not to scale) illustrates the path of the fast radio burst FRB 20220610A, from the distant galaxy where it originated all the way to Earth, in one of the Milky Way’s spiral arms. The source galaxy of FRB 20220610A, pinned down thanks to ESO’s Very Large Telescope, appears to be located within a small group of interacting galaxies. It’s so far away its light took eight billion years to reach us, making FRB 20220610A the most distant fast radio burst found to date. 
Full Size Image
Credit: ESO/M. Kornmesser

An international team has spotted a remote blast of cosmic radio waves lasting less than a millisecond. This 'fast radio burst' (FRB) is the most distant ever detected. Its source was pinned down by the European Southern Observatory’s (ESO) Very Large Telescope (VLT) in a galaxy so far away that its light took eight billion years to reach us. The FRB is also one of the most energetic ever observed; in a tiny fraction of a second it released the equivalent of our Sun’s total emission over 30 years.

The discovery of the burst, named FRB 20220610A, was made in June last year by the ASKAP radio telescope in Australia and it smashed the team’s previous distance record by 50 percent.

“Using ASKAP’s array of dishes, we were able to determine precisely where the burst came from,” says Stuart Ryder, an astronomer from Macquarie University in Australia and the co-lead author of the study published today in Science. “Then we used [ESO’s VLT] in Chile to search for the source galaxy, finding it to be older and further away than any other FRB source found to date and likely within a small group of merging galaxies.”

Astronomers reveal new map of dark matter, mass in universe

Victor M. Blanco 4-meter Telescope, left, at the Cerro Tololo Inter-American Observatory in Chile houses the camera used by the Dark Energy Survey.
Image Credit: Dark Energy Survey

For decades, cosmologists have mapped the distribution of mass in the universe, both visible material and the mysterious dark matter, in an effort to improve our understanding of these fundamental building blocks. Astronomer Eric Baxter from the University of Hawaiʻi Institute for Astronomy co-authored new research that traces the mass distribution in the universe in three dimensions. The updated analysis was published in Physical Review D.

Baxter and his University of Chicago collaborators, Chihway Chang and Yuuki Omori, compiled data using two different sky surveying methods. This new analysis shows that there is six times as much dark matter in the universe compared to matter that is visible—a finding that was already well-known. However, the team also found that the matter is not as clumpy as previously expected when compared to the current best model of the universe.

The researchers claim the findings could add to a growing body of evidence that there may be something missing from the existing standard model of the universe.

Ripples in the fabric of the universe may reveal the start of time

Numerical simulation of the neutron stars merging to form a black hole, with their accretion disks interacting to produce electromagnetic waves.
Illustration Credit: L. Rezolla (AEI) & M. Koppitz (AEI & Zuse-Institut Berlin

Scientists have advanced in discovering how to use ripples in space-time known as gravitational waves to peer back to the beginning of everything we know. The researchers say they can better understand the state of the cosmos shortly after the Big Bang by learning how these ripples in the fabric of the universe flow through planets and the gas between the galaxies.

“We can’t see the early universe directly, but maybe we can see it indirectly if we look at how gravitational waves from that time have affected matter and radiation that we can observe today,” said Deepen Garg, lead author of a paper reporting the results in the Journal of Cosmology and Astroparticle Physics. Garg is a graduate student in the Princeton Program in Plasma Physics, which is based at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL).

Garg and his advisor Ilya Dodin, who is affiliated with both Princeton University and PPPL, adapted this technique from their research into fusion energy, the process powering the sun and stars that scientists are developing to create electricity on Earth without emitting greenhouse gases or producing long-lived radioactive waste. Fusion scientists calculate how electromagnetic waves move through plasma, the soup of electrons and atomic nuclei that fuels fusion facilities known as tokamaks and stellarators.

The Most Precise Accounting Yet of Dark Energy and Dark Matter

G299 was left over by a particular class of supernovas called Type Ia. 
Credit: NASA/CXC/U.Texas

 Astrophysicists have performed a powerful new analysis that places the most precise limits yet on the composition and evolution of the universe. With this analysis, dubbed Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly finds that the cosmos is composed of about two-thirds dark energy and one-third matter — mostly in the form of dark matter — and is expanding at an accelerating pace over the last several billion years. However, Pantheon+ also cements a major disagreement over the pace of that expansion that has yet to be solved.

By putting prevailing modern cosmological theories, known as the Standard Model of Cosmology, on even firmer evidentiary and statistical footing, Pantheon+ further closes the door on alternative frameworks accounting for dark energy and dark matter. Both are bedrocks of the Standard Model of Cosmology but have yet to be directly detected and rank among the model's biggest mysteries. Following through on the results of Pantheon+, researchers can now pursue more precise observational tests and hone explanations for the ostensible cosmos.

"With these Pantheon+ results, we are able to put the most precise constraints on the dynamics and history of the universe to date," says Dillon Brout, an Einstein Fellow at the Center for Astrophysics | Harvard & Smithsonian. "We've combed over the data and can now say with more confidence than ever before how the universe has evolved over the eons and that the current best theories for dark energy and dark matter hold strong."

Simulation helps in the search for the origin of cosmic radiation

The colorful lines show how cosmic radiation is deflected in magnetic fields. The white straight lines represent a large-scale magnetic field. In addition, small-scale magnetic fields not shown here act on the orbits of the particles (colorful lines).
Credit: RUB, Dr. Lukas Merten

The cosmic radiation seems to be all around us. That is exactly what makes it difficult to find their sources. It would be helpful if you could trace your way back through space. A new program helps with this.

An international research team has developed a computer program that can be used to simulate the transport of cosmic radiation through space. The scientists hope to be able to solve the puzzle about the sources of cosmic radiation. So far it is unknown which celestial objects emit the high-energy radiation that patterns the earth from space. In order to be able to explain experimental data, theoretical models are required; the new computer simulation can deliver this. A team of researchers from the Ruhr University Bochum (RUB) describes the software in the journal of Cosmology and Astroparticle Physics, published online on September 12, 2022.

Like a uniformly illuminated sky during the day

Since their discovery of 100 years, researchers have been trying to decipher where the cosmic radiation comes from. The problem: viewed from Earth, it looks like heaven by day with the naked eye: it is illuminated almost everywhere where you look. Because the light of the sun is scattered in the earth's atmosphere and is distributed evenly over the entire sky. Cosmic radiation is also scattered on its way to earth - through interactions with cosmic magnetic fields. Only a uniformly illuminated picture can be seen from the earth; the origin of the radiation remains hidden.

No trace of dark matter halos

The dwarf galaxy NGC1427A flies through the Fornax galaxy cluster and undergoes disturbances which would not be possible if this galaxy were surrounded by a heavy and extended dark matter halo, as required by standard cosmology.
Credit: ESO

According to the standard model of cosmology, the vast majority of galaxies are surrounded by a halo of dark matter particles. This halo is invisible, but its mass exerts a strong gravitational pull-on galaxies in the vicinity. A new study led by the University of Bonn and the University of Saint Andrews (Scotland) challenges this view of the Universe. The results suggest that the dwarf galaxies of Earth’s second closest galaxy cluster – known as the Fornax Cluster – are free of such dark matter halos. The study appeared in the journal Monthly Notices of the Royal Astronomical Society.

Dwarf galaxies are small, faint galaxies that can usually be found in galaxy clusters or near larger galaxies. Because of this, they might be affected by the gravitational effects of their larger companions. “We introduce an innovative way of testing the standard model based on how much dwarf galaxies are disturbed by gravitational, tides’ from nearby larger galaxies”, said Elena Asencio, a PhD student at the University of Bonn and the lead author of the story. Tides arise when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth, which arise because the moon pulls more strongly on the side of Earth which faces the moon.

The Fornax Cluster has a rich population of dwarf galaxies. Recent observations show that some of these dwarfs appear distorted, as if they have been perturbed by the cluster environment. "Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to the standard model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster."