Determining star formation rates of active galactic nuclei host galaxies based on SED fitting with sub-mm data

TL;DR

This study measures star formation rates in active galactic nuclei host galaxies using SED fitting with new sub-mm data, revealing correlations with AGN outflow strength and Eddington ratios, and highlighting the importance of accounting for AGN dust contribution.

Contribution

It introduces a method combining sub-mm observations with SED fitting to accurately estimate SFRs in AGN hosts, considering AGN dust effects and comparing different SFR indicators.

Findings

Dust luminosity can be overestimated if AGN contribution is ignored.

SFR correlates with AGN outflow strength and Eddington ratio.

No evidence of immediate star formation quenching by AGN feedback.

Abstract

We present the star formation rate (SFR) measurements based on the spectral energy distribution (SED) analysis with new sub-mm fluxes combined with archival multi-wavelength data for a sample of 52 AGN host galaxies at z $<0.2$. We carried out sub-mm observations using the SCUBA-2 camera at the James Clerk Maxwell Telescope, and obtained flux or an upper limit at 450 and 850 $\mu$m for each target. By experimenting the effect of the AGN dust component in the SED fit, we find that dust luminosity can be overestimated if AGN contribution is ignored. While the SFR based on 4000{\AA} break shows a significant offset compared to dust luminosity based SFR, the SFR obtained by the artificial neural network (Ellison et al. 2016) generally shows consistency albeit with a large scatter. We find that SFR correlates with AGN outflow strength manifested by the [OIII] $\lambda 5007$ emission line, and that AGNs with higher Eddington ratios and stronger outflows are in general hosted by galaxies with higher SFR, which is consistent with the correlation reported by Woo et al. (2020). This suggests no instantaneous quenching of star formation due to AGN feedback.