A new theoretical model could redefine how we search for darkmatter đ! This model proposes that dark matter exists in two distinct forms whose particles must interact to annihilate, offering a solution to a long-standing astrophysical puzzle. Want to learn more? Click here: https://ow.ly/H5mR50YIpWk strophysics astronomy.
Berlin, Asher, Foster, Joshua W., Hooper, Dan, Krnjaic, Gordan.
A study led by UC Riverside physicist Hai-Bo Yu suggests that a new type of dark matter could explain three astrophysical puzzles across vastly different environments. Published in Physical Review Letters, the study proposes that dense clumps of self-interacting dark matter (SIDM)âeach about a million times the mass of the sunâcan account for unusual gravitational effects observed in gravitational lenses, stellar streams, and satellite galaxies.
Dark matter, which makes up about 85% of the universeâs matter, cannot be seen directly. The standard model assumes it is âcoldâ and collisionless, meaning that particles pass through one another without interacting. This model struggles, however, to explain certain high-density structures observed in the universe.
Yuâs work instead focuses on SIDM, in which dark matter particles collide and exchange energy. These interactions can trigger âgravothermal collapse,â forming extremely dense, compact cores.
Astronomers from the Chinese Academy of Sciences (CAS) have employed the Lijiang 2.4-m telescope to perform optical photometric and spectroscopic observations of a core-collapse Type IIP supernova designated SN 2024abfl. Results of the observational campaign, published April 2 on the arXiv, preprint server, deliver essential information regarding the origin of this peculiar supernova.
Deep underground in a Canadian mine, a refrigerator nearly 1,000 times colder than outer space has just reached its target temperatureâa milestone that brings scientists one step closer to potentially detecting dark matter, the invisible material thought to make up most of the mass in the universe.
For researchers at Texas A&M University, the moment is especially meaningful. Their custom-designed detectors sit at the heart of the Super Cryogenic Dark Matter Search (SuperCDMS), and they only become sensitive enough to detect possible dark-matter interactions at these extreme temperatures. SuperCDMS is in SNOLAB, an underground research facility in a nickel mine near Sudbury, Ontario.
Scientists there are targeting âlight dark matter,â a much lower-mass form of dark matter thatâs even harder to detect.
The absence of a signal could itself be a signal. This is the idea behind a new study published in the Journal of Cosmology and Astroparticle Physics, which aims to redefine how we search for dark matter, showing that it may not be necessary to find the same âcluesâ everywhere in order to interpret it.
In particular, the study suggests that even if we observe a certain type of signal at the center of our galaxyâan excess of gamma radiation that could result from the annihilation of dark matter particlesâfailing to detect the same signal in other systems, such as dwarf galaxies, is not enough to rule out this explanation.
Dark matter, in fact, may not consist of a single particle, but of multiple slightly different components, whose behavior varies depending on the cosmic environment.
How fast can a galaxy build ordered magnetic fields spanning thousands of light-years? Existing theories say several billion years, but observations of galaxies in our universe imply shorter timescales. In a study published in the Physical Review Letters and highlighted in the Physics magazine, scientists propose an explanation that resolves this contradiction. They say that the collapse of plasma clouds during the formation of galaxies could significantly accelerate the growth of these magnetic fields.
Almost all visible matter in our universe is in the form of plasma, which can be stirred by forces related to gravity, temperature gradients and rotation. If these lead to turbulent flow, the dynamo theory predicts that the existing magnetic fields in the plasma are amplified. The dynamo theory is our primary framework for understanding the origin of cosmic magnetic fields.
âHowever, dynamo theory has its limitations,â says Pallavi, an assistant professor at the International Centre for Theoretical Sciences (ICTS) and an author of the study. âIn particular, it struggles to explain observations of young galaxies with robust magnetic fields across thousands of light-years.â
Supermassive black holes at the centers of galaxies are one of the most active fields of research in astronomy. In order to accumulate their enormous masses, they must merge with each other. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn has found direct evidence of two supermassive black holes in the galaxy Markarian 501, which orbit each other very closely. This could be the first time that a pair has been detected that is about to merge. This provides a unique opportunity to better understand a central process in galaxy evolution.
The findings suggest that there is a supermassive black hole at the center of almost every large galaxy, with a mass millions or even billions of times greater than that of our sun. It is still unclear exactly how they can reach such enormous masses. Collecting (accreting) gas from the surrounding area alone would take too long, so it is likely that they have to merge with other massive black holes. Galaxy collisions have been observed throughout our universe. It is thus very likely that the supermassive black holes at the centers of these colliding galaxies also merge, first orbiting each other ever closer and ultimately coalescing into one.
By analyzing the data from the Pan-Andromeda Archaeological Survey (PandAS), European astronomers have discovered a new satellite of the Andromeda galaxy. The newfound object, which received the designation Andromeda XXXVI, appears to be an ultra-faint dwarf galaxy. The finding is reported in a paper published March 30 on the arXiv preprint server.
The so-called ultra-faint dwarf galaxies (UFDs) are the least luminous, most dark matter-dominated, and least chemically evolved galaxies known. Therefore, they are perceived by astronomers as the best candidate fossils from the universe at its early stages.
Now, a team of astronomers, led by Joanna D. Sakowska of the Institute of Astrophysics of Andalusia in Spain, reports the finding of a new UFD. Andromeda XXXVI was first spotted and classified as a candidate UFD by amateur astronomer Giuseppe Donatiello during a systematic, visual inspection search of public images from the full PAndAS footprint. Sakowska and her colleagues recently performed follow-up deep imaging of Andromeda XXXVI with the Roque de los Muchachos Observatory, which confirmed the UFD nature of this galaxy.
