[IPARCOS astro] May 22nd, 2024 "Feeding supermassive black holes with galaxy interactions"

[IPARCOS astro-seminar] 22/05/2024
Dr. Sandra Raimundo (University of Southampton, UK)
Title: Feeding supermassive black holes with galaxy interactions
Abstract: It is well established that supermassive black holes grow via the accretion of gas. Identifying the mechanisms that provide this gas to the black holes is important to understand how supermassive black holes grow and what physical conditions favour the onset of black hole activity. However, it is challenging to find clear observational signatures of black hole feeding/fuelling. Interactions between galaxies often leave an imprint that is observable in the aftermath of the interaction, such as a misalignment in the stellar and gas motions of galaxies. It has been suggested by simulations that misalignment may drive galaxy gas all the way to the central supermassive back hole, one of the ingredients needed to fuel supermassive black holes.
I will show observational evidence that galaxy interactions, such as major mergers, minor mergers or galaxy flybys, indeed provide the necessary conditions to fuel black hole activity and growth. I will present a method that uses kinematically misaligned gas to observationally identify galaxies that went through an interaction. With this method we have recently shown that galaxies that have misaligned gas have a higher observed fraction of active black holes. This is the first time that an observational connection is seen between the process of formation and/or presence of misaligned structures and the fuelling of active supermassive black holes. I will discuss the implications of this black hole fuelling mechanism for different galaxy types and their evolution.