AGN Feedback in the Hot Halo of NGC 4649

TL;DR

This study uses deep Chandra observations of NGC 4649 to reveal X-ray cavities and structures linked to AGN activity, indicating non-thermal pressure contributions and radiatively inefficient accretion, with implications for galaxy feedback processes.

Contribution

It provides detailed evidence of AGN feedback effects in NGC 4649's hot halo, including cavity formation, pressure analysis, and non-thermal components, advancing understanding of galaxy evolution mechanisms.

Findings

Detection of cavities, ripples, and rings in the hot ISM.

Evidence of non-thermal pressure from radio jets and lobes.

The nucleus exhibits highly sub-Bondi accretion and low radiative efficiency.

Abstract

Using the deepest available $\textit{Chandra}$ observations of NGC 4649 we find strong evidences of cavities, ripples and ring like structures in the hot interstellar medium (ISM) that appear to be morphologically related with the central radio emission. These structures show no significant temperature variations in correspondence with higher pressure regions ($0.5\mbox{kpc}<r<3\mbox{kpc}$). On the same spatial scale, a discrepancy between the mass profiles obtained from stellar dynamic and $\textit{Chandra}$ data represents the telltale evidence of a significant non-thermal pressure component in this hot gas, which is related to the radio jet and lobes. On larger scale we find agreement between the mass profile obtained form $\textit{Chandra}$ 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. Consistently 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 similar behavior to those of other giant elliptical galaxies.