Giuseppe Murante, Matteo Calabrese, Gabriella De Lucia, Pierluigi Monaco, Stefano Borgani, Klaus Dolag
We present results from high--resolution cosmological hydrodynamical
simulations of a Milky--Way-sized halo, aimed at studying the effect of
feedback on the nature of gas accretion. Simulations include a model of
inter-stellar medium and star formation, in which SN explosions provide
effective thermal feedback. We distinguish between gas accretion onto the halo,
which occurs when gas particles cross the halo virial radius, and gas accretion
onto the central galaxy, which takes place when gas particles cross the inner
one-tenth of the virial radius. Gas particles can be accreted through three
different channels, depending on the maximum temperature value, $T_{\rm max}$,
reached during the particles' past evolution: a cold channel for $T_{\rm
max}<2.5 \times 10^5$ K, a hot one for $T>10^6$K, and a warm one for
intermediate values of $T_{\rm max}$. We find that the warm channel is at least
as important as the cold one for gas accretion onto the central galaxy. This
result is at variance with previous findings that the cold mode dominates gas
accretion at high redshift. We ascribe this difference to the different
supernova feedback scheme implemented in our simulations. While results
presented so far in the literature are based on uneffective SN thermal feedback
schemes and/or the presence of a kinetic feedback, our simulations include only
effective thermal feedback. We argue that observational detections of a warm
accretion mode in the high--redshift circum-galactic medium would provide
useful constraints on the nature of the feedback that regulates star formation
in galaxies.
View original:
http://arxiv.org/abs/1202.5212
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