  Motivated by the observed shortfall of baryons in the local universe, we
investigate the ability of high resolution cosmic microwave background (CMB)
experiments to detect hot gas in the outer regions of nearby group halos. We
construct hot gas models with the gas in hydrostatic equilibrium with the dark
matter and described by a polytropic equation of state. We also consider models
that add entropy to the gas in line with constraints from X-ray observations.
We calculate the thermal Sunyaev-Zel'dovich (SZ) signal in these halos and
compare it to the anticipated sensitivities of forthcoming SZ survey
experiments such as ACT, PLANCK and SPT. Using a multi-frequency Wiener filter
we derive SZ detectability limits as a function of halo mass and redshift in
the presence of galactic and extragalactic foregrounds and the CMB. We find
that group-sized halos with virial masses below 1e14 M_solar can be detected at
z < 0.05 with the threshold mass dropping to 3-4e13 M_solar at z < 0.01. The SZ
distortion of nearby group-sized halos can thus be mapped out to the virial
radius by these CMB experiments, beyond the sensitivity limits of X-ray
observations. These measurements will provide a unique probe of hot gas in the
outer regions of group halos, shedding insight into the local census of baryons
and the injection of entropy into the intragroup medium from non-gravitational
feedback.
