Probing Hot Gas in Galaxy Groups through the Sunyaev-Zeldovich Effect
  We investigate the potential of exploiting the Sunyaev-Zeldovich effect (SZE)
to study the properties of hot gas in galaxy groups. It is shown that, with
upcoming SZE surveys, one can stack SZE maps around galaxy groups of similar
halo masses selected from large galaxy redshift surveys to study the hot gas in
halos represented by galaxy groups. We use various models for the hot halo gas
to study how the expected SZE signals are affected by gas fraction, equation of
state, halo concentration, and cosmology. Comparing the model predictions with
the sensitivities expected from the SPT, ACT and Planck surveys shows that a
SPT-like survey can provide stringent constraints on the hot gas properties for
halos with masses M ~> 10^{13} h^{-1}Msun. We also explore the idea of using
the cross correlation between hot gas and galaxies of different luminosity to
probe the hot gas in dark matter halos without identifying galaxy groups to
represent dark halos. Our results show that, with a galaxy survey as large as
the Sloan Digital Sky Survey and with the help of the conditional luminosity
function (CLF) model, one can obtain stringent constraints on the hot gas
properties in halos with masses down to 10^{13} h^{-1}Msun. Thus, the upcoming
SZE surveys should provide a very promising avenue to probe the hot gas in
relatively low-mass halos where the majority of L*-galaxies reside.
