This New Map of 1.3 Million Quasars Is A Powerful Tool

This figure from the research shows the sky distribution of the new Quaia quasar catalogue in Galactic coordinates and is displayed using a Mollweide projection. The grey region across the center is the Milky Way, a blind spot in the Quaia catalogue. Image Credit: K. Storey-Fisher et al. 2024

Quasars are the brightest objects in the Universe. The most powerful ones are thousands of times more luminous than entire galaxies. They’re the visible part of a supermassive black hole (SMBH) at the center of a galaxy. The intense light comes from gas drawn toward the black hole, emitting light across several wavelengths as it heats up.

But quasars are more than just bright ancient objects. They have something important to show us about the dark matter.

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Colliding Neutron Stars are the Ultimate Particle Accelerators

This artist’s impression shows two tiny but very dense neutron stars at the point at which they merge and explode as a kilonova. Such a very rare event is expected to produce both gravitational waves and a short gamma-ray burst, both of which were observed on 17 August 2017 by LIGO–Virgo and Fermi/INTEGRAL respectively. Subsequent detailed observations with many ESO telescopes confirmed that this object, seen in the galaxy NGC 4993 about 130 million light-years from the Earth, is indeed a kilonova. Such objects are the main source of very heavy chemical elements, such as gold and platinum, in the Universe.

Gamma-ray telescopes observing neutron star collisions might be the key to identifying the composition of dark matter. One leading theory explaining dark matter it that is mostly made from hypothetical particles called axions. If an axion is created within the intensely energetic environment of two neutron stars merging, it should then decay into gamma-ray photons which we could see using space telescopes like Fermi-LAT.

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Webb Can Directly Test One Theory for Dark Matter

Stephan's Quintet of galaxies as seen by JWST. The telescope could provide sharp views of even more distant galaxies that could help solve part of the dark matter mystery in galaxy formation. Courtesy: JWST.

What is it about galaxies and dark matter? Most, if not all galaxies are surrounded by halos of this mysterious, unknown, but ubiquitous material. And, it also played a role in galaxy formation. The nature of that role is something astronomers are still figuring out. Today, they’re searching the infant Universe, looking for the tiniest, brightest galaxies. That’s because they could help tell the tale of dark matter’s role in galactic creation.

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“Seeing” the Dark Matter Web That Surrounds the Coma Cluster

Artist's impression of Dark matter in the Coma Cluster region. Credit: HyeongHan et al.

According to our predominant cosmological models, Dark Matter makes up the majority of mass in the Universe (roughly 85%). While it is not detectable in visible light, its influence can be seen based on how it causes matter to form large-scale structures in our Universe. Based on ongoing observations, astronomers have determined that Dark Matter structures are filamentary, consisting of long, thin strands. For the first time, using the Subaru Telescope, a team of astronomers directly detected Dark Matter filaments in a massive galaxy cluster, providing new evidence to test theories about the evolution of the Universe.

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Dark Matter Might Help Explain How Supermassive Black Holes Can Merge

A lopsided starburst galaxy known as NGC 1313. Credit: International Gemini Observatory

Although the exact nature of dark matter continues to elude astronomers, we have gained some understanding of its general physical properties. We know how it clusters around galaxies, how it makes up much of the matter in the Universe, and even how it can interact with itself. Now a new study looks at just how fast dark matter can move.

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There’s Less Dark Matter at the Core of the Milky Way

A study by MIT physicists suggest the Milky Way’s gravitational core may be lighter in mass, and contain less dark matter, than previously thought. Credits:Credit: ESA/Gaia/DPAC, Edited by MIT News

Science really does keep you on your toes. First there was matter and then there were galaxies. Then those galaxies had more stuff in the middle so stars further out were expected to move slowly, then there was dark matter as they actually seemed to move faster but now they seem to be moving slower in our Galaxy so perhaps there is less dark matter than we thought after all! 

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Dark Matter Could Map the Universe's Early Magnetic Fields

Illustration of magnetic field lines running between galaxies. Credit: Chris Mihos/ CWRU

We think of magnetic fields as a part of planets and stars. The Earth and Sun have relatively strong magnetic fields, as do more exotic objects such as neutron stars and the accretion disks of black holes. But magnetic field lines also run throughout galaxies, and even between the vast voids of intergalactic space. Magnetic fields are quite literally everywhere, and we aren’t entirely sure why. One idea is that faint magnetic fields formed during the earliest moments of the Universe. If that’s the case, we might be able to prove it through the distribution of dark matter.

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Dark Matter Could Cause Jupiter’s Night Side to Glow

One of the aspects of our study of the universe that fascinates me is the hunt for dark matter. That elusive material that doesn’t interact with much makes it difficult but not impossible to detect.  Gravitational lenses are one such phenomena that point to its existence indeed it allows us to estimate how much there is in galaxy clusters. A paper now suggests that observations of Jupiter by Cassini in 2000 suggest we may be able to detect it using planets too. 

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Will Wide Binaries Be the End of MOND?

Artist view of an orbiting binary star. Credit: ESO/L. Calçada

It’s a fact that many of us have churned out during public engagement events; that at least 50% of all stars are part of binary star systems. Some of them are simply stunning to look at, others present headaches with complex orbits in multiple star systems. Now it seems wide binary stars are starting to shake the foundations of physics as they question the very theory of gravity. 

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There Aren’t Many Galaxies Like The Milky Way Nearby. Now We Know Why

Antennas of the Very Large Array against the Milky Way. Credit: NRAO/AUI/NSF/Jeff Hellerman

The Milky Way is a barred spiral galaxy, maybe even a grand design spiral galaxy. We can’t be sure from our vantage point. But one thing is certain: there aren’t many disk galaxies like it in our part of the Universe called the supergalactic plane.

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