# Star formation in galaxies hosting AGN: A flat trend of star-formation rate with X-ray luminosity of galaxies hosting AGN in the SCUBA-2 Cosmology Legacy Survey

## TL;DR

This study uses deep submillimeter and infrared data to analyze star formation in X-ray selected AGN host galaxies at redshifts 1-3, finding no correlation between star formation rates and AGN luminosity, suggesting AGN activity does not quench or enhance star formation.

## Contribution

It provides new evidence that star formation rates in AGN host galaxies are flat across a wide range of X-ray luminosities, using a large sample and multi-wavelength stacking analysis.

## Key findings

- Star formation rates range from 80 to 600 solar masses per year.
- No trend of SFR with X-ray luminosity within redshift bins.
- AGN activity does not significantly affect host galaxy star formation.

## Abstract

Feedback processes from active galactic nuclei (AGN) are thought to play a crucial role in regulating star formation in massive galaxies. Previous studies using \textit{Herschel} have resulted in conflicting conclusions as to whether star formation is quenched, enhanced, or not affected by AGN feedback. We use new deep 850 $\mu$m observations from the SCUBA-2 Cosmology Legacy survey (S2CLS) to investigate star formation in a sample of X-ray selected AGN, probing galaxies up to $L_{0.5-7~\rm keV} = 10^{46}$ erg s$^{-1}$. Here we present the results of our analysis on a sample of 1957 galaxies at $ 1 < z < 3 $, using both S2CLS and ancilliary data at seven additional wavelengths (24--500 \mcm) from \textit{Herschel} and \textit{Spitzer}. We perform a stacking analysis, binning our sample by redshift and X-ray luminosity. By fitting analytical spectral energy distributions (SEDs) to decompose contributions from cold and warm dust, we estimate star-formation rates for each `average' source. We find that the average AGN in our sample resides in a star-forming host galaxy, with SFRs ranging from 80 - 600 $M_{\odot}$ year$^{-1}$. Within each redshift bin, we see no trend of SFR with X-ray luminosity, instead finding a flat distribution of SFR across $\sim$3 orders of magnitude of AGN luminosity. By studying instantaneous X-ray luminosities and SFRs, we find no evidence that AGN activity affects star formation in host galaxies.