قالب وردپرس درنا توس
Home / Science / The Dark Matter breakthrough allowed the discovery of three of the most popular theories, all at once

The Dark Matter breakthrough allowed the discovery of three of the most popular theories, all at once



Distribution of dark matter

Two numerical simulations predict the distribution of dark matter around a galaxy similar to our own. The left panel assumes that dark matter particles move rapidly in the early universe (warm dark matter), while the right panel assumes that dark matter particles move slowly (dark matter). cold). The warm dark matter model predicts that there will be fewer small clusters of dark matter around our Galaxy, and therefore less satellite galaxies to live in these small dark matter clusters. By measuring the number of satellite galaxies, scientists can distinguish between these dark matter models. (Image from Bullock & Boylan-Kolchin, 2017 Annual Review of Astronomy and Astrophysics, based on simulations of V. Robles, T. Kelley and B. Bozek)

Observe the surrounding dwarf galaxies Galaxy issued simultaneous restrictions on three common theories of dark matter.

A group of scientists led by cosmologists from the Department of Energy’s SLAC and Fermi national accelerator laboratories have laid down some of the tightest constraints for the nature of dark matter, based on on a set of a few dozen small, faint satellite galaxies orbiting the Milky Way to determine what kind of dark matter could lead to the population of galaxies we see today.

Risa Wechsler, director of the Kavli Institute for Astrophysics and Space (KIPAC) at SLAC and Stanford University, says the new study has important implications not just how closely it can limit dark matter but also about what it might limit. “One of the things I think is really interesting is that we can actually start exploring the three most common theories about dark matter, all at once,” she said.

Dark matter makes up 85% of the matter in the universe and has very weak interactions with ordinary matter except for gravity. Its effects can be seen in the shape of galaxies and in the large-scale structure of the universe, but no one is sure exactly what dark matter is. In the new study, researchers focus on three broad possibilities for the nature of dark matter: relatively fast or “warm” moving dark matter; another form of “interacting” dark matter collides with protons enough to be heated in the early universe, with the result of galaxy formation; and a third particle, extremely light, known as “dim dark matter”, through quantum mechanics spanning thousands of light years.

To test those models, researchers first developed computer simulations of dark matter and its effect on the formation of relatively small galaxies within thick patches of dark matter. Denser is found orbiting larger galaxies.

“The faintest galaxies are one of the most valuable tools we must learn about matter,” said Ethan Nadler, lead author and graduate student at Stanford and SLAC. dark because they are very sensitive to some of its basic properties. For example, if dark matter moves too fast or gains too much energy through long-term interactions with ordinary matter, those galaxies will not form in the first place. The same goes for dim dark matter, which if stretched out enough, would wipe out young galaxies with quantum vibrations.

By comparing such models with a faint list of dwarf galaxies from the Dark Energy Survey and the Pan-Response System and Panoramic Survey Telescope, or Pan-STARRS, the researchers had New limits on the likelihood of such events can be introduced. In fact, those bounds are strong enough that they begin to limit the same dark matter possibilities that direct detection experiments are currently probing – and with a new stream of data from the Heritage Survey of The Rubin Observatory for Space and Time is expected over the next few years, the limits will only be tighter.

“It’s interesting to see the dark matter problem being attacked from many different experimental angles,” said Fermilab and University of Chicago Scientist Alex Drlica-Wagner, collaborator in Dark Energy Survey and one of the main authors of the paper. “This is an important measurement for DES and I am very hopeful that future cosmic surveys will help us learn in depth what dark matter is.”

Still, Nadler says, “there’s a lot more theoretical work to be done.” For one thing, there are several models of dark matter, including one proposed that can interact strongly with itself, where researchers are uncertain about the consequences for galaxy formation. There are also other astronomical systems, such as stellar lines that can reveal new details as they collide with dark matter.

Reference: “Milky Way Satellite Investigation. III. Constraints on Dark Matter Properties from Observations of Milky Way Satellite Galaxies ”by EO Nadler, A. Drlica-Wagner, K. Bechtol, S. Mau, RH Wechsler, V. Gluscevic, K. Boddy, AB Pace, TS Li, ​​M. McNanna, AH Riley, J. García-Bellido, Y.-Y. Mao, G. Green, DL Burke, A. Peter, B. Jain, TMC Abbott, M. Aguena, S. Allam, J. Annis, S. Avila, D. Brooks, M. Carrasco Kind, J. Carretero, M Costanzi, LN da Costa, J. De Vicente, S. Desai, HT Diehl, P. Doel, S. Everett, AE Evrard, B. Flaugher, J. Frieman, DW Gerdes, D. Gruen, RA Gruendl, J. Gschwend, G. Gutierrez, SR Hinton, K. Honscheid, D. Huterer, DJ James, E. Krause, K. Kuehn, N. Kuropatkin, O. Lahav, MAG Maia, JL Marshall, F. Menanteau, R. Miquel, A. Palmese, F. Paz-Chinchón, AA Plazas, AK Romer, E. Sanchez, V. Scarpine, S. Serrano, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, MEC Swanson , G. Tarle, DL Tucker, AR Walker, W. Wester (DES Collaboration), July 31, 2020, Astrophysics> Cosmology and Nongalactic Astrophysics.
arXiv: 2008.00022

Research is a collaborative effort in the Dark Energy Survey. The research was supported by the National Science Foundation Graduate Fellowship, the Department of Energy’s Science Office through SLAC and Stanford University.




Source link