[Normal Galaxies, Clusters of Galaxies -- Oral ]

AGN feedback in galaxy groups: The case of HCG 62

Myriam Gitti, SAO-CfA
E. O'Sullivan (SAO-CfA, Birmingham Univ.), S. Giacintucci (SAO-CfA), L. David (SAO-CfA), J. Vrtilek (SAO-CfA), S. Raychaudhury (Birmingham Univ.), C. Jones(SAO-CfA), W. Forman(SAO-CfA)

As a part of an ongoing study of 18 groups of galaxies showing evidence for AGN/hot gas interaction, we report on the results of an analysis of Chandra, XMM and GMRT data of the X-ray bright compact group HCG 62. This is one of the few groups known to possess very clear, small X-ray cavities in the inner regions. The ~50 ks Chandra image combined with the new ~100 ks XMM exposure of HCG 62 allow us to derive with unprecedented accuracy the radial profiles and 2-D distribution of temperature, density and metal abundances. At higher frequency (1.4 GHz or above) the cavities show minimal if any radio emission, but the radio is clearly detected in the cavities with the new GMRT data at lower frequency (610 MHz and below). By means of the synergy of X-ray and low-frequency radio observations we compare and discuss the morphology, luminosity and pressure of the gas and of the radio source. We find that the cavities are close to pressure balance, and that the jets have a "light" hadronic content. Thanks to the high spatial resolution of the Chandra surface brightness and temperature profiles, we also identify a shock front located around 35 kpc to the south-west of the group center, with a Mach number ~1.45 and E_shock ~ 3 x E_cavities. Such a shock may have significantly heated the gas close to the southern cavity, as indicated by the temperature map.