The Radio Galaxy Population in the SIMBA SImulations

Nicole Thomas*, Romeel Dave, Matt J. Jarvis, Daniel Angles-Alcazar

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We examine the 1.4GHz radio luminosities of galaxies arising from star formation and active galactic nuclei (AGN) within the state-of-the-art cosmological hydrodynamic simulation Simba. Simba grows black holes via gravitational torque limited accretion from cold gas and Bondi accretion from hot gas, and employs AGN feedback including jets at low Eddington ratios. We define a population of radio loud AGN (RLAGN) based on the presence of ongoing jet feedback. Within RLAGN we define high and low excitation radio galaxies (HERGs and LERGs) based on their dominant mode of black hole accretion: torque limited accretion representing feeding from a cold disk, or Bondi representing advection-dominated accretion from a hot medium. Simba predicts good agreement with the observed radio luminosity function (RLF) and its evolution, overall as well as separately for HERGs and LERGs. Quiescent galaxies with AGN-dominated radio flux dominate the RLF at > $\sim 10^{22-23}$ W Hz$^{-1}$, while star formation dominates at lower radio powers. Overall, RLAGN have higher black hole accretion rates and lower star formation rates than non-RLAGN at a given stellar mass or velocity dispersion, but have similar black hole masses. Simba predicts a LERG number density of 8.53 Mpc$^{-3}$, $\sim 10\times$ higher than for HERGs, broadly as observed. While LERGs dominate among most massive galaxies with the largest black holes and HERGs dominate at high specific star formation rates, they otherwise largely populate similar-sized dark matter halos and have similar host galaxy properties. Simba thus predicts that deeper radio surveys will reveal an increasing overlap between the host galaxy demographics of HERGs and LERGs.
Original languageEnglish
Pages (from-to)3492-3509
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume503
Issue number3
Early online date9 Mar 2021
DOIs
Publication statusPublished - 1 May 2021

Keywords / Materials (for Non-textual outputs)

  • astro-ph.GA

Fingerprint

Dive into the research topics of 'The Radio Galaxy Population in the SIMBA SImulations'. Together they form a unique fingerprint.

Cite this