A Deep Chandra View of Abell 2597: Bubbles, Shocks, Cold Fueling, and a Plasma Depletion Layer

TL;DR

This study uses deep X-ray, radio, and infrared observations to explore how AGN feedback influences the intracluster medium and cold gas fueling in Abell 2597, revealing recurrent outbursts, plasma depletion layers, and cold accretion processes.

Contribution

It provides new evidence for cold, turbulence-driven accretion fueling AGN activity, challenging hot gas accretion models in galaxy cluster cores.

Findings

Detection of multiple X-ray cavities and weak shocks indicating recurrent AGN outbursts.

Identification of a plasma depletion layer shaped by sloshing motions and magnetic field amplification.

Support for chaotic cold accretion as the primary fueling mechanism exceeding Bondi accretion rates.

Abstract

To examine how AGN feedback shapes the intracluster medium (ICM) and fuels black hole accretion in the cool-core galaxy cluster Abell 2597, we present deep ($\sim$600 ks) Chandra X-ray observations complemented by archival GMRT radio and SINFONI near-infrared data. Radio-mode AGN activity has inflated seven X-ray cavities and driven one to three potential weak shocks ($M \sim 1.05-1.14$) extending to $\sim 150$ kpc, suggesting recurrent outbursts occurring on $\sim 10^7$ year timescales. We also detect a narrow, $\sim$57 kpc X-ray surface brightness deficit-a potential plasma depletion layer-likely shaped by residual sloshing motions that amplified magnetic fields and/or displaced gas within the cluster core. Although the AGN injects $\sim 10^{44}$ erg s$^{-1}$ of energy, comparable to the cluster's cooling luminosity, radiative cooling persists at $\sim$15 M$_{\odot} $yr$^{-1}$, replenishing the billion solar mass cold gas reservoir at the heart of the brightest cluster galaxy. Sustaining this level of activity requires a continuous fuel supply, yet the estimated Bondi accretion power ($\sim 2 \times 10^{43}$ erg s$^{-1}$) falls an order of magnitude short of the observed cavity power, suggesting that "hot" gas fueling is insufficient. Instead, archival ALMA observations continue to support a chaotic cold accretion scenario, where turbulence-driven condensation fuels the AGN at rates exceeding Bondi accretion, sustaining a self-regulated feedback cycle that repeatedly shapes the core of Abell 2597.