The relationship between warm and hot gas-phase metallicity in massive elliptical galaxies and the influence of AGN feedback

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Main Authors: Olivares, Valeria, Su, Yuanyuan, Temi, Pasquale, Eskenasy, Ryan, Russell, Helen, Gaspari, Massimo, Salome, Philippe, Combes, Francoise, Sun, Ming, Treister, Ezequiel, Fogarty, Kevin, Jimenez-Gallardo, Ana, Lagos, Patricio
Format: Preprint
Published: 2025
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author Olivares, Valeria
Su, Yuanyuan
Temi, Pasquale
Eskenasy, Ryan
Russell, Helen
Gaspari, Massimo
Salome, Philippe
Combes, Francoise
Sun, Ming
Treister, Ezequiel
Fogarty, Kevin
Jimenez-Gallardo, Ana
Lagos, Patricio
author_facet Olivares, Valeria
Su, Yuanyuan
Temi, Pasquale
Eskenasy, Ryan
Russell, Helen
Gaspari, Massimo
Salome, Philippe
Combes, Francoise
Sun, Ming
Treister, Ezequiel
Fogarty, Kevin
Jimenez-Gallardo, Ana
Lagos, Patricio
contents Warm ionized gas is ubiquitous at the centers of X-ray bright elliptical galaxies. While it is believed to play a key role in the feeding and feedback processes of supermassive black holes, its origins remain under debate. Existing studies have primarily focused on the morphology and kinematics of warm ionized gas. This work aims to provide a new perspective on warm (10,000 K) ionized gas and its connection to X-ray-emitting hot gas (>10^6 K) by measuring and comparing their metallicities. We conducted a joint analysis of 13 massive elliptical galaxies using MUSE/VLT and Chandra observations. Emission-line ratios were measured for the warm ionized gas using MUSE observation, and used to infer the ionization mechanisms and derive metallicities of the warm ionized gas using HII, and LIN(E)R calibrations. We also computed the warm phase metallicity using X-ray/EUV, and pAGB stars models. For two sources at higher redshift, direct Te method was also used to measure warm gas metallicities. Our observations reveal that most sources exhibit composite ionization, with contributions from both star formation and LINER-like emission. A positive linear correlation was found between the gas-phase metallicities of the warm and hot phases, ranging from 0.3 to 1.5 Zsun, and suggest the intimate connection between the two gas phases, likely driven by gas cooling and/or mixing. In some sources the warm gas metallicity shows a central drop. A similar radial trend has been reported for the hot gas metallicity in some galaxy clusters. The ionization mechanisms of cooling flow elliptical galaxies are diverse, suggesting multiple channels for powering the warm ionized gas. The large variation in the warm gas metallicity further suggests that cold gas mass derived under the assumption of solar metallicity for the CO-to-H2 conversion factor needs to be revised by approximately an order of magnitude.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10587
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The relationship between warm and hot gas-phase metallicity in massive elliptical galaxies and the influence of AGN feedback
Olivares, Valeria
Su, Yuanyuan
Temi, Pasquale
Eskenasy, Ryan
Russell, Helen
Gaspari, Massimo
Salome, Philippe
Combes, Francoise
Sun, Ming
Treister, Ezequiel
Fogarty, Kevin
Jimenez-Gallardo, Ana
Lagos, Patricio
Astrophysics of Galaxies
Warm ionized gas is ubiquitous at the centers of X-ray bright elliptical galaxies. While it is believed to play a key role in the feeding and feedback processes of supermassive black holes, its origins remain under debate. Existing studies have primarily focused on the morphology and kinematics of warm ionized gas. This work aims to provide a new perspective on warm (10,000 K) ionized gas and its connection to X-ray-emitting hot gas (>10^6 K) by measuring and comparing their metallicities. We conducted a joint analysis of 13 massive elliptical galaxies using MUSE/VLT and Chandra observations. Emission-line ratios were measured for the warm ionized gas using MUSE observation, and used to infer the ionization mechanisms and derive metallicities of the warm ionized gas using HII, and LIN(E)R calibrations. We also computed the warm phase metallicity using X-ray/EUV, and pAGB stars models. For two sources at higher redshift, direct Te method was also used to measure warm gas metallicities. Our observations reveal that most sources exhibit composite ionization, with contributions from both star formation and LINER-like emission. A positive linear correlation was found between the gas-phase metallicities of the warm and hot phases, ranging from 0.3 to 1.5 Zsun, and suggest the intimate connection between the two gas phases, likely driven by gas cooling and/or mixing. In some sources the warm gas metallicity shows a central drop. A similar radial trend has been reported for the hot gas metallicity in some galaxy clusters. The ionization mechanisms of cooling flow elliptical galaxies are diverse, suggesting multiple channels for powering the warm ionized gas. The large variation in the warm gas metallicity further suggests that cold gas mass derived under the assumption of solar metallicity for the CO-to-H2 conversion factor needs to be revised by approximately an order of magnitude.
title The relationship between warm and hot gas-phase metallicity in massive elliptical galaxies and the influence of AGN feedback
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2511.10587