Space and astronomy news
One outstanding mystery in astrophysics is known as the “final parsec problem.” Simulations predict that binary black holes should stall out in the last stages of their merger. Since we’re detecting the gravitational waves from these mergers, we know it happens, but how? A new paper proposes that ultralight dark matter near the black holes could help to carry away orbital energy from the black holes, driving them together.
Thanks to new techniques, astronomers are mapping the Universe with more precision, finding galaxies with more and less dark matter. Now astronomers think they’ve found one that’s almost all dark matter with few stars. Dubbed “Nube”, the galaxy contains about the same mass as the Large Magellanic Cloud, measuring 22,000 light-years across, with almost no stars inside it. This is the most massive and extended “Almost Dark Galaxy” astronomers have ever found.
The search for dark matter continues, with astronomers developing new hypotheses to search for this invisible gravitational influence on the Universe. One proposed dark matter particle candidate is the axion, which physicists have searched for since the 1970s. One characteristic of axions is that they should convert into light in a strong electromagnetic field. According to a new paper, they should create a faint glow around pulsars, generating intense magnetic fields.
Astronomers still don’t know what dark matter is, but one of its characteristics is that it has a small “cross section,” which means that it doesn’t interact with regular matter or itself. However, if it’s possible to trap dark matter in a region dense enough, it might interact and annihilate, releasing gamma radiation. A new paper suggests that astronomers use gamma-ray observatories to scan white dwarf stars to discover whether there’s an excess of radiation coming from them. This might mean there’s dark matter trapped inside, providing more clues to its nature.
Dark matter might have its own force, mediated by dark photons similar to the way electromagnetism is mediated by photons. A new study shows that not only are dark photons consistent with experiments in particle physics, they could also solve the g-2 anomaly for muons.
Astronomers have measured the Milky Way’s shape and found that the disk is warped and not a flat spiral like many of the galaxies we see in the Universe. It was assumed a collision with another galaxy in the ancient past caused this warping. Observations have shown that the galactic stellar halo is tilted concerning the galactic plane, and a new theory proposes that the dark matter halo is tilted, too. This tilt might be torquing the galaxy, causing the warp that astronomers have observed.
When you look at most galaxies in the Universe, you’re looking at the homes of supermassive black holes. It now appears that quasars, which are active galaxies spitting out huge amounts of radiation from the region around their black holes, also have massive dark matter halos. It turns out they’ve always had them. And, their …
Continue reading “Quasars Have Always Had Dark Matter Halos”
Dark matter remains mysterious and… well… dark. While we don’t yet have a definite idea of what this cosmic “stuff” is made of, astronomers are learning more about its distribution throughout the Universe. Since we can’t see it directly, observers need to use indirect methods to detect it. One way is through gravitational lensing. Another …
A gap in astronomical knowledge is Cosmic Dawn, a time when the first stars in the Universe formed, ending the cosmological dark ages. If there was dark matter at this early time, its decay might have heated up the intergalactic medium, sending out a signal that could be detectable today. A new paper suggests that the newly built Hydrogen Epoch of Reionization Array (HERA) telescope could measure this dark matter decay with 1,000 hours of observation or constrain its presence by three orders of magnitude.
If dark matter is made of heavy particles, they could become captured by the gravitational field of massive objects like stars or planets. Constrained in a small area, these particles could crash into one another and annihilate with radiation. Astronomers have searched through 10 years of data captured by the IceCube Neutrino Observatory at the South Pole for any evidence of this dark matter annihilation. Although they didn’t detect any evidence, the next generation IceCube Update will significantly improve the search.