Effects of Baryon Mass Loss on Profiles of Large Galactic Dark Matter Haloes

CINTHIA RAGONE-FIGUEROA; GIAN LUIGI GRANATO; MARIO G. ABADI

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2012 p. 3243 - 3250

0035-8711

We perform controlled numerical experiments to asses the effect of baryon mass loss on theinner structure of large galactic dark matter (DM) haloes. This mass expulsion is intendedto mimic both the supernova and active galactic nucleus (AGN) feedbacks, as well as theevolution of stellar populations. This study is meant in particular for precursors of massiveearly-type galaxies (ETGs), wherein strong AGN feedback (often dubbed ?quasi-stellar objectmode? in galaxy formation models) has been proposed to remove on a short time-scale, of theorder of a few dynamical times, a substantial fraction of their baryons. In a previous paperwe evaluated the observational consequences (size increase) of this process on the galacticstructure. Here we focus on the distribution of DM in the galactic region. It is shown that theinner region of the DM halo expands and its density profile flattens by a sizeable amount, withlittle dependence on the expulsion time-scale. We also evaluate the effect of the commonlymade approximation of treating the baryonic component as a potential that changes in intensitywithout any variation in shape. This approximation leads to some underestimates of the haloexpansion and its slope flattening. We conclude that cuspy density profiles in ETGs could bedifficult to reconcile with an effective AGN (or stellar) feedback during the evolution of thesesystems.