CHANDRA OBSERVATIONS OF THE GALAXY GROUP AWM 5: COOL CORE REHEATING AND THERMAL CONDUCTION SUPPRESSION

We present an analysis of a 40 ks Chandra observation of the galaxy group AWM 5. It has a small (similar to 8 kpc) dense cool core with a temperature of similar to 1.2 keV and the temperature profile decreases at larger radii, from similar to 3.5 keV just outside the core to similar to 2 keV at similar to 300 kpc from the center. The abundance distribution shows a hole in the central similar to 10 kpc, where the temperature declines sharply. An abundance of at least a few times solar is observed similar to 15-20 kpc from the center. The deprojected electron density profile shows a break in slope at similar to 13 kpc and can be fit by two beta models, with beta = 0.72(-0.11)(+0.16) and r(c) = 5.7(-1.5)(+1.8) kpc, for the inner part, and beta = 0.34 +/- 0.01 and r(c) = 31.3(-5.5)(+5.8) kpc, for the outer part. The mass fraction of hot gas is fairly flat in the center and increases for r > 30 kpc up to a maximum of similar to 6.5% at r similar to 380 kpc. The gas cooling time within the central 30 kpc is smaller than a Hubble time, although the temperature only declines in the central similar to 8 kpc region. This discrepancy suggests that an existing cooling core has been partially reheated. In particular, thermal conduction could have been a significant source of reheating. In order for heating due to conduction to balance cooling due to emission of X-rays, conductivity must be suppressed by a large factor (at least similar to 100). Past active galactic nuclei activity (still visible as a radio source in the center of the group) is, however, the most likely source that reheated the central regions of AWM 5. We also studied the properties of the ram pressure stripped tail in the group member NGC 6265. This galaxy is moving at M approximate to 3.4(-0.6)(+0.5)(v similar to 300 km s(-1)) through the hot group gas. The physical length of the tail is similar to 42 kpc and its mass is 2.1 +/- 0.2 x 10(9) M(circle dot).