ACTIVE GALACTIC NUCLEUS FEEDBACK IN THE HOT HALO OF NGC 4649

Abstract

Using the deepest available Chandra observations of NGC 4649, we find strong evidences of cavities, ripples, and ring-like structures in the hot interstellar medium that appear to be morphologically related with the central radio emission. These structures show no significant temperature variations in correspondence with higher pressure regions (0.5 kpc < r < 3 kpc). On the same spatial scale, a discrepancy between the mass profiles obtained from stellar dynamic and Chandra data represents the telltale evidence of a significant nonthermal pressure component in this hot gas, which is related to the radio jet and lobes. On a larger scale we find agreement between the mass profile obtained from Chandra data and planetary nebulae and globular cluster dynamics. The nucleus of NGC 4649 appears to be extremely radiatively inefficient, with highly sub-Bondi accretion flow. Consistent with this finding, the jet power evaluated from the observed X-ray cavities implies that a small fraction of the accretion power calculated for the Bondi mass accretion rate emerges as kinetic energy. Comparing the jet power to radio and nuclear X-ray luminosity, the observed cavities show behavior similar to those of other giant elliptical galaxies.