Universe Today
Astronomy’s Decades-Long Quest To Understand Cosmic Topology
Cosmic topology is as esoteric as cosmology can get. But a growing number of astrophysicists think it holds keys to understanding the universe on its largest scales.
Cosmology
The study of the universe as a whole
Recent Articles
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Tens of Thousands of Fast Radio Bursts Could Help Solve the Greatest Cosmic Mysteries
A new study led by researchers from Caltech demonstrates the effectiveness of Fast Radio Bursts (FRBs) as a tool for measuring cosmological distances and the clustering of matter.
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Dense Galaxies Are Carving Out A Bubble in the Early Universe
Light could only travel freely in the Universe after cosmic reionization. Before that, neutral hydrogen stopped photons from travelling. The JWST has found evidence of an overdensity of galaxies carving out a bubble of reionization. Is this how it all started?
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How Big Can The Universe's First Starbursts Get?
As our telescopes have improved and we’ve been able to peer farther back in time, we’ve begun finding more fascinating features of the universe. But one thing we definitely haven’t found yet is Population III (Pop III) stars. These were the earliest stars in the universe, formed completely from pristine hydrogen and helium, with no “metals” (i.e. elements heavier than those two) polluting their processes. They are also theorized to be absolutely massive, and “die with passion” as Bill Wurtz once put it in a famous YouTube video. A new paper, available in pre-print form on arXiv by Tae Bong Jeon from the Cosmic Frontier Center at the University of Texas at Austin, looks at just how massive those starbursts could be, and whether the James Webb Space Telescope could detect one.
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Do Black Holes Grow Along With the Universe? A New Study Says Yes
We know the universe is constantly expanding. We also know that gravitationally bound objects, such as solar systems and black holes, seem to be immune to that expansion. But a new paper, available in pre-print on arXiv by theoretical physicists Valerio Faraoni and Massimiliano Rinaldi challenges that assumption. They suggest that black holes can’t just ignore the expanding universe around them. Instead they have to expand along with it.
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Astronomers Hear the Faint Whispers of Cosmic Hydrogen from the Distant Past.
Astronomers have directly detected an extremely faint radio signal from hydrogen gas billions of light years away, demonstrating a powerful new way to map the Universe.
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Pulsar Timing Arrays Could Look for Evidence of Dark Matter Stars
Pulsar Timing Arrays have been used to observe the background of gravitational waves in our galaxy. We aren't certain of their origin, but a new study shows a strong source could be early supermassive giants known as dark stars.
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New Study Expands Search for "Dark Photons," a Leading Dark Matter Candidate
Cross-disciplinary research at Perimeter Institute and University of Maryland shows that dark photons could be lurking in more places than previously thought.
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Meet ASTRID, the New High-Resolution Cosmological Simulation
The ASTRID cosmological simulation has run from the Universe's early days up to the present day, z=0. ASTRID is larger than some other simulations, and smaller than others. But with a higher number of particles, it has higher-resolution than its fellows. Among other things, this can tell astronomers where to look for gravitational waves from black hole mergers with future GW observatories.
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A Tool for Measuring the Mass of the Stars, Galaxies, and the Universe Gets a Tweak
How do scientists know the mass of the Universe? Measuring it has traditionally relied on knowing how many stars there are in galaxies, as well as clouds of gas and dust, and associated dark matter. Astronomers generally use the mass of the brightest stars to estimate the mass of an entire galaxy. That means the rest of a galaxy's stars and its dark matter are essentially invisible. For decades, astronomers estimated the number of small, unseen stars in clusters and galaxies using a mathematical rule that assumed stars formed in roughly the same mass proportions everywhere in the Universe. That tool is called the initial mass function (IMF). It describes how many stars of each size there are in a given cluster or galaxy. However, there are challenges with the way it's currently applied because of assumptions it contains.
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Hubble Solves a Mystery About the Milky Way's Early Years
New data from NASA’s Hubble Space Telescope shows definitive evidence of a dwarf galaxy merging with the young Milky Way galaxy in the earliest phases of its evolution. This finding extends our knowledge of our galaxy’s history 1.8 billion years farther back in time than before.
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New Simulations Show How Galactic Centers Grow Together
Using a state-of-the-art galaxy simulation, a team led by scientists from the Leibniz Institute for Astrophysics Potsdam (AIP) gained new insights into the processes shaping galactic centres across the Universe and the formation history of the Milky Way.
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Two Million X-Ray Sources, and One Cluster That Doesn't Fit
The eROSITA telescope has released its second great catalogue of the X-ray sky with close to two million sources across half the sky, roughly double what it published before. Buried in it is a result from Bonn that matters more than the headline number. A team there went after the faintest part of a massive galaxy cluster, the outer region where fresh material is still arriving along threads of gas stretching between clusters. Nobody had measured that emission before. The gas turns out to be hotter, denser and poorer in heavy elements than the models say it should be.
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The Dark Matter Detector in the Scottish Borders
Hunting for dark matter usually means building something enormous and burying it — a tank of liquid xenon in a mine, a magnet the size of a lorry, decades of engineering and a great deal of money. A team in Japan have just done it differently. They realised that the Earth's own magnetic field is larger than any magnet we could ever construct, and that the gap between the ground and the ionosphere behaves as a natural resonating cavity, ringing at around eight cycles per second. If dark matter is what some theorists suspect, it should leave a faint hum in that cavity. So they went looking, not with a new instrument, but in ten years of geomagnetic readings already recorded at a quiet observatory in Dumfriesshire in Scotland.
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What Killed Galaxies in the Early Universe?
Galaxies in the infancy of the Universe are the building blocks of more modern galaxies. They began as small "shreds" of material that coalesced over time to form larger ones. That's why astronomers use observatories such as the James Webb Space Telescope (JWST) to study the young Universe. The light from those early objects appears in the infrared part of the spectrum, which JWST is tuned to see.
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A Distant Primordial Object May Be a Newborn Little Red Dot
Little Red Dots are among the most intriguing discoveries made to date by the infrared-sensitive James Webb Space Telescope (JWST). They are distant, small objects that appear red in the JWST observations and they've only been known since 2024. More than 300 of them have been found as part of JWST's infrared surveys of the early Universe.
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Probing the Universe's Missing Matter With Mysterious Fast Radio Bursts
Astronomers aren't certain where Fast Radio Bursts come from. But they still have utility. They can use them to find the Universe's "missing matter."
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Astronomers are Hunting Down the Elusive Population III Stars
It’s hard hunting down the oldest stars in the universe. These behemoths, known as Population (or Pop) III stars, are a missing link in cosmology between the primordial soup that was the early universe and the complex, “metal”-rich cosmos we’re familiar with today. But we’re slowly getting a better idea of where to look for them, and a new paper available in pre-print on arXiv from Alessandra Venditti of the University of Texas at Austin and her co-authors, highlights some of the recent advances and potential new surveying techniques that could eventually help us definitively find these massive, bright, early sparks in the universe.
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How the SKA Will Use Fast Radio Bursts to Decode the Universe
There are parts of the universe that are extremely hard to see, even for our most advanced telescopes. Gas and dust don’t emit any light, and are only visible by the light that they happen to block from stars and galaxies. Magnetic fields are even harder since regular light typically passes right through them. However, according to a new paper available in pre-print on arXiv, by Manisha Caleb of the University of Sydney and their co-authors, we’re currently commissioning a potentially game-changing new tool that could use a particularly violent astronomical phenomenon to provide new insight into these hard to see places.
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Astronomers Use a Neutron Star Merger to Measure Cosmic Expansion
Swinburne University of Technology and CSIRO have combined telescope and gravitational wave data in an attempt to unlock the true value of the Universe's expansion. Existing measurements of the Hubble Constant have split cosmologists for more than a decade.