ITC Colloquium - Mikhail Medvedev (KU)


Thursday, April 20, 2017, 11:00am to 12:00pm



Cosmology of flavor-mixed dark matter

Abstract: The standard Lambda-CDM cosmological model is successful at describing the distribution of matter at large scales but faces problems at galactic scales. Pundits blame for this the poorly understood or modeled baryonic physics, e.g., star formation, feedback via stellar wind, supernova outflows and black hole jets, the influence of magnetic fields and cosmic rays, etc. Whereas the role of baryons is still debated, alternative models of dark matter (DM) have actively been explored. A natural possibility is that DM particles are flavor-mixed, so that several mass states are present now. I will describe that interactions of mixed particles can lead to "quantum evaporation" (or the "Munchhausen effect"), which has been overlooked for decades. Next, I will discuss the simplest two-component model (2cDM), which accounts for the process, and its cosmological implications. These include the change of the mass and velocity functions of halos, the modification of halo density profiles, the growth of black holes by accretion of DM, and how it can evade the early universe freeze-out, decay, "bullet cluster" and other constraints. I will show that the results of N-body simulations with the 2cDM are in remarkable agreement with observations across several orders of magnitude in halo mass -- from dwarfs to clusters -- thus potentially resolving the CDM problems. The 2cDM model makes specific predictions for direct and indirect detection DM experiments.

See also: Colloquium, 2016-17