Observations of dwarf galaxies around Milky Way have given simultaneous limitations to three popular theories of dark matter.
A team of scientists led by cosmologists from the SLAC Department of Energy and the national Farm Accelerator Laboratories have placed some of the even narrower constraints on the nature of dark matter by drawing a collection of several dozen small, faint satellite galaxies. , orbiting the Milky Way Orbit determine what types of dark matter could lead to the population of galaxies we see today.
The new study is significant not only for how narrowly it can limit dark matter, but also for what it can limit, said Risa Wechsler, director of the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at SLAC and Stanford University. “One of the things I think is really exciting is that we are able to start investigating three of the most popular theories of dark matter, all at the same time,” she said.
Dark matter makes up 85 percent of the matter in the universe and interacts very poorly with ordinary matter, except through gravity. Its impact can be seen in the shapes of galaxies and the large-scale structure of the universe, but no one is sure exactly what dark matter is. In the new study, researchers focused on three broad possibilities for the nature of dark matter: relatively fast or warm “warm” matter; another form of “interaction” of dark matter that strikes enough protons that have warmed up in the early universe, with consequences for the formation of the galaxy; and a third, extremely light particle, known as “obscure dark matter,” which through quantum mechanics effectively extends thousands of light years.
To test those models, the researchers first developed computer simulations of dark matter and its effects on the formation of relatively small galaxies within the densest particles of dark matter, found to circulate larger galaxies.
“The weakest galaxies are among the most valuable tools we need to learn about dark matter because they are sensitive to some of its basic properties right away,” said Ethan Nadler, lead author of the study and graduate student. at Stanford University and SLAC. For example, if dark matter moves a little faster or has gained a lot of energy through recent interactions with normal matter, those galaxies will not form in the first place. The same goes for obscure dark matter, which if stretched enough, will wipe out new galaxies with quantum fluctuations.
By comparing such models with a catalog of faint dwarf galaxies from the Dark Energy Observation and Panoramic Survey Telescope and Rapid Reaction System, or Pan-STARRS, researchers were able to set new limits on the likelihood of events. Like that. In fact, these limits are so strong that they begin to limit the same possibilities of dark matter direct detection experiments are now trying – and with a new stream of data from the Rubin Observatory Survey of Space and Time Survey expected in the coming years, the boundaries will only be strengthened.
“It is exciting to see the problem of dark matter being attacked from so many different angles,” Fermilab said. University of Chicago scientist Alex Drlica-Wagner, a Dark Energy contributor and one of the lead authors in the paper. “This is a historic measurement for DES, and I am very hopeful that future cosmological studies will help us reach the end of what is dark matter.”
Still, Nadler said, “there is a lot of theoretical work to be done.” For one thing, there are a number of models of dark matter, including a proposed form that can strongly interact with itself, where researchers are unsure of the consequences for the formation of the galaxy. There are other astronomical systems, such as star streams that can reveal new details when they collide with dark matter.
Reference: “Milky Way Satellite Census. III. Constraints on the properties of dark matter from observations of the 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, et al. . 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.
The research was a collaborative effort within the Dark Energy Survey. The research was supported by a Graduate Foundation of the National Science Foundation, the Department of Energy Science Office through SLAC, and Stanford University.