'Heating' galactic cold dark matter through gaseous fluctuations

Giovedi 1 Giugno alle 16 in aula multimediale, il Prof. Amr Elzant (British University of Egypt) terra’ un seminario dal titolo: 'Heating' galactic cold dark matter through gaseous fluctuations"            

Abstract: Dark matter is required to keep galaxies and galaxy clusters bound, to explain the features of the cosmic microwave background and the large scale structure of the universe, as well as its expansion history. Indeed, the parameters of our universe are now known with significant precision, but most of its content is missing.   

The cold dark matter (CDM) model for structure structure formation in an initially nearly homogeneous  universe is quite successful on large scales.

However, it faces several, probably related, problems on galactic scales.

These are connected to the exceedingly large central densities of bound CDM structures ('haloes'); in order to fit the outer rotation curves of galaxies, CDM seems to predict  central densities that are in excess of what is observed.

Several remedies for this (so called cusp/core) problem have been proposed, including modifications in the particle physics  model (with, e.g. 'warm' or 'fuzzy' or interacting DM), and the astrophysics of galaxy formation.

I review these briefly before focussing on the effect of the interaction  between a  clumpy gaseous component and the central regions of haloes,  presenting a model for stochastic coupling between a fluctuating gaseous medium and the CDM.

In this context, the fluctuations in the gaseous medium are driven by energy input from exploding stars or an active galactic centre. The associated random forces lead to the 'heating'  of the CDM in the centres of galaxies, decreasing  halo central densities and achieving better agreement with observations     

Contact: Nicola De Filippis