Gas Sloshing and Bubbles in the Galaxy Group NGC 5098
  We present results from Chandra observations of the galaxy pair and
associated galaxy group NGC 5098, and find evidence for both gas sloshing and
AGN heating. The X-ray brightness images show diffuse emission with a spiral
structure, centered on NGC 5098a, and a sharp edge in the diffuse emission
surrounding much of the galaxy at about 30 kpc. The spiral structure in the
X-ray surface brightness and temperature maps, the offset between the peak of
the cool gas and the central AGN, and the structure of the cold front edges all
suggest gas sloshing in the core. The most likely perturber is the nearby
galaxy NGC 5098b, which has been stripped of its gaseous atmosphere. Detailed
images of the core reveal several X-ray cavities, two of which, just north and
southeast of the central AGN, correlate with radio emission and have bright
X-ray rims, similar to buoyant bubbles seen in the ICM of other systems. We
estimate the pressures in the bubbles and rims and show that they are roughly
equal, consistent with these being young features, as suggested by their close
proximity to the central AGN. We assume that the other X-ray cavities in the
core, which show no correlation with existing radio observations, are ghost
cavities from previous AGN outbursts. An estimate of the mechanical energy
required to inflate the cavities indicates that it is sufficient to offset
radiative cooling of the gas for 15 Myr. Therefore, for a typical cycle time of
10^7 yrs, the central AGN energy output is enough to balance cooling over long
timescales.
