The relationship between warm and hot gas-phase metallicity in massive elliptical galaxies and the influence of active galactic nucleus feedback
Year: 2025
Type: article
Abstract: Context. 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. Aims. 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. Methods. We conducted a joint analysis of 13 massive elliptical galaxies using MUSE/VLT and Chandra observations. Emission-line ratios, including [OIII]/H β , [NII]/H α , were measured using MUSE observations to infer the ionization mechanisms. We derive metallicities of the warm ionized gas using HII, and LINER calibrations. We also computed the warm phase metallicity using X-ray/EUV, and pAGB star models. For two sources at higher redshifts, the direct T e method was also used to measure warm gas metallicities. The metallicity of the hot gas was measured using Chandra X-ray observations. Results. Our observations reveal that most sources exhibit composite ionization, with contributions from both star formation and LINER-like emission. The four sources with the lowest star formation rates in our sample – Centaurus, M87, M84, and Abell 496 – are dominated by LINER 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 Z ⊙ . 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. Conclusions. The ionization mechanisms of cooling flow elliptical galaxies are diverse, suggesting multiple channels for powering the warm ionized gas. The positive correlation found in warm and hot gas metallicities suggest the intimate connection between the two gas phases, likely driven by gas cooling and/or mixing. 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-H 2 conversion factor needs to be revised by approximately an order of magnitude.
Source: Astronomy and Astrophysics
Institutions: Universidad de Santiago de Chile, University of Kentucky, Ames Research Center, University of Nottingham, University of Modena and Reggio Emilia, Centre National de la Recherche Scientifique, Collège de France, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères, University of Alabama in Huntsville, University of Tarapacá, European Southern Observatory, European Southern Observatory, Universidad Andrés Bello
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: G1462813675, G2428672771, A COMPREHENSIVE VIEW OF THE CONNECTION BETWEEN SUPERMASSIVE BLACK HOLE GROWTH AND MAJOR GALAXY MERGERS, COSMIC BALLET - THE INTERPLAY OF HEATING, COOLING, AND METALS AT THE CORES OF GALAXY CLUSTERS AND GROUPS, TWELVE BILLION YEARS THAT TRANSFORMED GALAXIES INTO WHAT THEY ARE TODAY: GALAXY EVOLUTION IN HIGH-DENSITY ENVIRONMENTS ACROSS TIME, SPECTRO-TEMPORAL STUDIES OF AGN POPULATIONS, G8104139569, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA)
OpenAlex ID: W4416652339