Investigating quenching in Recently Quenched Elliptical galaxies with HI studies

TL;DR

This study investigates the neutral hydrogen content and evolutionary pathways of Recently Quenched Elliptical galaxies, revealing that gas retention and halo mass influence their rapid quenching and subsequent evolution, challenging traditional gas depletion models.

Contribution

It introduces a multi-wavelength analysis of RQEs, identifying a critical halo mass threshold and proposing two distinct evolutionary pathways for galaxy quenching.

Findings

RQEs retain substantial HI reservoirs despite quenching.

A halo mass threshold at $ ext{log} M_{halo} = 12.1$ M$_ ext{sun}$ influences quenching pathways.

Two evolutionary pathways: rapid quenching with mergers and possible rejuvenation.

Abstract

Recently Quenched Elliptical galaxies (RQEs) represent a critical phase in the transition from star-forming to quiescent galaxies. However, the mechanisms driving their quenching remain elusive. We conduct a multi-wavelength analysis of 155 RQEs, along with their precursors (preRQEs) and descendants (postRQEs), focusing on their neutral hydrogen (HI) content and star formation properties. Contrary to conventional quenching models emphasizing gas depletion, RQEs retain substantial HI reservoirs ($f_{\text{gas}} \geq 17\%$), suggesting that quenching is not primarily driven by gas exhaustion. We identify a critical halo mass threshold at $\log M_{\text{halo}} = 12.1 M_{\odot}$, delineating different evolutionary pathways for RQEs. This threshold aligns with the transition from cold-mode to hot-mode gas accretion in theoretical models. RQEs in lower-mass halos ($\log M_{\text{halo}} < 12.1 M_{\odot}$) likely experience rapid quenching, possibly initiated by major mergers, followed by brief AGN activity and sustained LINER emission. We propose two evolutionary pathways: (a) rapid quenching via major mergers followed by AGN/LINER activity and passive evolution, and (b) rapid quenching followed by rejuvenation through minor mergers before evolving into more massive, long-term quenched ellipticals. These results challenge the conventional understanding of galaxy quenching, especially in low-density environments where RQEs typically reside. Our findings suggest that while RQEs may follow a rapid quenching pathway, their evolution is influenced by interactions between gas accretion modes, feedback mechanisms, and environmental factors. Future observations with advanced radio interferometers like SKA will be crucial for elucidating the quenching mechanisms in RQEs and their role in galaxy evolution.