Facial reconstruction

Search LJMU Research Online

Browse Repository | Browse E-Theses

Galaxy mergers can initiate quenching by unlocking an AGN-driven transformation of the baryon cycle

Davies, JJ, Pontzen, A and Crain, RA (2022) Galaxy mergers can initiate quenching by unlocking an AGN-driven transformation of the baryon cycle. Monthly Notices of the Royal Astronomical Society, 515 (1). pp. 1430-1443. ISSN 0035-8711

Galaxy mergers can initiate quenching by unlocking an AGN driven transformation of the baryon cycle.pdf - Published Version

Download (2MB) | Preview


We use zoom simulations to show how merger-driven disruption of the gas disc in a galaxy provides its central active galactic nucleus (AGN) with fuel to drive outflows that entrain and expel a significant fraction of the circumgalactic medium (CGM). This in turn suppresses replenishment of the interstellar medium, causing the galaxy to quench up to several Gyr after the merger. We start by performing a zoom simulation of a present-day star-forming disc galaxy with the EAGLE galaxy formation model. Then, we re-simulate the galaxy with controlled changes to its initial conditions, using the genetic modification technique. These modifications either increase or decrease the stellar mass ratio of the galaxy's last significant merger, which occurs at $z$ ≈ 0.74. The halo reaches the same present-day mass in all cases, but changing the mass ratio of the merger yields markedly different galaxy and CGM properties. We find that a merger can unlock rapid growth of the central supermassive black hole if it disrupts the co-rotational motion of gas in the black hole's vicinity. Conversely, if a less disruptive merger occurs and gas close to the black hole is not disturbed, the AGN does not strongly affect the CGM, and consequently the galaxy continues to form stars. Our result illustrates how a unified view of AGN feedback, the baryon cycle and the interstellar medium is required to understand how mergers and quenching are connected over long time-scales.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2002 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: Astronomy & Astrophysics; 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
SWORD Depositor: A Symplectic
Date Deposited: 17 Oct 2022 12:54
Last Modified: 17 Oct 2022 13:00
DOI or ID number: 10.1093/mnras/stac1742
URI: https://researchonline.ljmu.ac.uk/id/eprint/17860
View Item View Item