Cosmological growth and feedback from supermassive black holes

TL;DR

This paper models the growth of supermassive black holes through accretion, analyzing their feedback effects and evolution from redshift 3 to 0, highlighting the significance of FR II radio sources in feedback at higher redshifts.

Contribution

It introduces a simple evolutionary model for black hole growth that matches observed X-ray luminosity functions and explores feedback mechanisms, including radio jet contributions.

Findings

Active galaxies in low accretion mode dominate feedback at z<1.5.

FR II radio sources significantly contribute to feedback at z>1.5.

Approximately one-sixth of FR II jet power does PdV work in lobes.

Abstract

We develop a simple evolutionary scenario for the growth of supermassive black holes (BHs), assuming growth due to accretion only, to learn about the evolution of the BH mass function from $z=3$ to 0 and from it calculate the energy budgets of different modes of feedback. We tune the parameters of the model by matching the derived X-ray luminosity function (XLF) with the observed XLF of active galactic nuclei. We then calculate the amount of comoving kinetic and bolometric feedback as a function of redshift, derive a kinetic luminosity function and estimate the amount of kinetic feedback and $PdV$ work done by classical double Fanaroff-Riley II (FR II) radio sources. We also derive the radio luminosity function for FR IIs from our synthesized population and set constraints on jet duty cycles. Around 1/6 of the jet power from FR II sources goes into $PdV$ work done in the expanding lobes during the time the jet is on. Anti hierarchical growth of BHs is seen in our model due to addition of an amount of mass being accreted on to all BHs independent of the BH mass. The contribution to the total kinetic feedback by active galaxies in a low accretion, kinetically efficient mode is found to be the most significant at $z<1.5$. FR II feedback is found to be a significant mode of feedback above redshifts $z\sim 1.5$, which has not been highlighted by previous studies.