Direct Evidence for Termination of Obscured Star Formation by Radiatively Driven Outflows in FeLoBAL QSOs

TL;DR

This study provides direct evidence that radiatively driven outflows from AGN suppress obscured star formation in FeLoBAL QSOs, with stronger outflows correlating with reduced starburst activity, supporting the quasar mode feedback model.

Contribution

It presents the first direct observational evidence linking AGN-driven outflows to the termination of obscured star formation in FeLoBAL QSOs.

Findings

FeLoBAL QSOs have IR luminosities > 10^12 Solar luminosities.

Strong AGN outflows are associated with less than 25% star formation contribution.

No correlation between IR luminosity of AGN and star formation suppression.

Abstract

We use SDSS spectra and optical to far-infrared photometry for a sample of 31 FeLoBAL QSOs to study the relationship between the AGN-driven outflows, and obscured star formation in their host galaxies. We find that FeLoBAL QSOs invariably have IR luminosities exceeding 10^12 Solar luminosities. The AGN supplies 75% of the total IR emission, on average, but with a range from 20% to 100%. We find a clear anticorrelation between the strength of the AGN-driven outflows and the contribution from star formation to the total IR luminosity, with a much higher chance of seeing a starburst contribution in excess of 25% in systems with weak outflows than in systems with strong outflows. Moreover, we find no evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGN act to curtail obscured star formation in the host galaxies of reddened QSOs to less than ~25% of the total IR luminosity. This is the most direct evidence yet obtained for `quasar mode' AGN feedback.