The Distribution and Condition of the Warm Molecular Gas in Abell 2597 and Sersic 159-03

TL;DR

This study maps and analyzes the distribution, kinematics, and excitation conditions of molecular and ionised gas in the central regions of two cool core galaxy clusters, revealing interactions with active nuclei and consistent excitation mechanisms.

Contribution

It provides detailed spatial and dynamical characterization of warm molecular and ionised gas in Abell 2597 and Sersic 159-03, highlighting their interaction with active galactic nuclei.

Findings

Gas extends up to 20 kpc from galaxy centers.

Gas phases are spatially and dynamically correlated.

Gas excitation is consistent with a single heating source.

Abstract

We have used the SINFONI integral field spectrograph to map the near-infrared K-band emission lines of molecular and ionised hydrogen in the central regions of two cool core galaxy clusters, Abell 2597 and Sersic 159-03. Gas is detected out to 20 kpc from the nuclei of the brightest cluster galaxies and found to be distributed in clumps and filaments around it. The ionised and molecular gas phases trace each other closely in extent and dynamical state. Both gas phases show signs of interaction with the active nucleus. Within the nuclear regions the kinetic luminosity of this gas is found to be somewhat smaller than the current radio luminosity. Outside the nuclear region the gas has a low velocity dispersion and shows smooth velocity gradients. There is no strong correlation between the intensity of the molecular and ionised gas emission and either the radio or X-ray emission. The molecular gas in Abell 2597 and Sersic 159-03 is well described by a gas in local thermal equilibrium (LTE) with a single excitation temperature T_exc ~ 2300 K. The emission line ratios do not vary strongly as function of position, with the exception of the nuclear regions where the ionised to molecular gas ratio is found decrease. These constant line ratios imply a single source of heating and excitation for both gas phases.