Constraints on Feedback in the local Universe: The relation between star formation and AGN activity in early type galaxies

TL;DR

This study investigates the relationship between star formation and AGN activity in nearby early type galaxies, revealing that most are inactive, with only a small fraction showing low-level star formation and radio emission, likely linked to stellar mass.

Contribution

It provides a multi-wavelength analysis of star formation and AGN activity in early type galaxies, highlighting the low prevalence of powerful AGNs and the potential mass dependence of radio and star formation activity.

Findings

Most early type galaxies are not powerful AGNs.

Star formation is present in about 7% of the sample with low SFR.

Radio power correlates with stellar mass and SFR.

Abstract

We address the relation between star formation and AGN activity in a sample of 231 nearby ($0.0002<z<0.0358$) early type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR and radio. Our results indicate that early type galaxies in the current epoch are rarely powerful AGNs, with $P<10^{22}\,WHz^{-1}$ for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The SFR of these galaxies is less than 0.1 $M_{\odot}yr^{-1}$. They also tend to be radio faint ($P<10^{22}\,WHz^{-1}$). There is a nearly equal fraction of star forming galaxies in radio faint ($P<10^{22}\,WHz^{-1}$) and radio bright galaxies ($P\geq10^{22}\,WHz^{-1}$) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies (BCGs) follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.