11. January 2018

 

RELATIVITY SEMINAR
Bremen-Oldenburg

 

Date & Time:Thursday, 11. January 2018
14:30
Location:University of Bremen, ZARM
Room 1280
Speaker:Andreas Krut
La Sapienza University, Rome, Italy
Title:Novel constraints on fermionic dark matter from galactic observables 

Abstract: We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Argüelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model for fermion masses above keV successfully describes the DM halos in galaxies and predicts the existence of a denser quantum core towards the centre of each configuration. We demonstrate here that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for the finite Galaxy size, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range mc² = 48 - 345 keV the DM halo distribution fulfils the most recent data of the Milky Way rotation curves while harbours a dense quantum core of 4E6 Msun within the S2 star pericentre. In particular, for a fermion mass of mc² = 48 keV the model is able to explain the DM halos from typical dwarf spheroidal to normal elliptical galaxies while harbouring dark and massive compact objects from 1E3 Msun up to 1E8 Msun at their respective centres. The model is shown to be in good agreement with different observationally inferred universal relations, such as the ones connecting DM halos with supermassive dark central objects. Finally, the model provides a natural mechanism for the formation of supermassive BHs as heavy as few 1E8 Msun. We argue that larger BH masses (1E9 - 1E10 Msun) may be achieved by assuming subsequent accretion processes onto the above heavy seeds, depending on accretion efficiency and environment.