The beta problem: A study of Abell 262

We present an investigation of the dynamical state of the cluster A262. Exi sting optical line-of-sight velocities for select cluster galaxies have bee n augmented by new data obtained with the Automated Multi-Object Spectrogra ph at Lick Observatory. We find evidence for a virialized early-type popula tion distinct from a late-type population infalling from the Pisces-Perseus supercluster ridge. We also report on a tertiary population of low-luminos ity galaxies the velocity dispersion of which distinguishes them from both the early- and late-type galaxies. We supplement our investigation with an analysis of archival X-ray data. A temperature is determined using ASCA GIS data, and a gas profile is derived from ROSAT HRI data. The increased stat istics of our sample results in a picture of A262 with significant differen ces from earlier work. A previously proposed solution to the "beta -problem " in A262 in which the gas temperature is significantly higher than the gal axy temperature is shown to result from using too low a velocity dispersion for the early-type galaxies. Our data present a consistent picture of A262 in which there is no "beta -problem," and the gas and galaxy temperature a re roughly comparable. There is no longer any requirement for extensive gal axy-gas feedback to drastically overheat the gas with respect to the galaxi es. We also demonstrate that entropy floor models can explain the recent di scovery that the beta values determined by cluster gas and the cluster core radii are correlated.