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

TL;DR

This study provides evidence that radiatively driven outflows from AGN in reddened QSOs can suppress star formation, with stronger outflows correlating with reduced starburst IR contributions, indicating a negative feedback mechanism.

Contribution

It demonstrates a clear link between AGN-driven outflows and the suppression of star formation, highlighting the impact of outflows on galaxy evolution.

Findings

FeLoBAL QSOs are always IR-luminous with L_IR > 10^{12} L_sun.

AGN contributes on average 76% to IR luminosity, ranging from 20% to 100%.

Stronger outflows are associated with lower star formation contribution.

Abstract

We present optical to far-infrared photometry of 31 reddened QSOs that show evidence for radiatively driven outflows originating from AGN in their rest-frame UV spectra. We use these data to study the relationships between the AGN-driven outflows, and the AGN and starburst infrared luminosities. We find that FeLoBAL QSOs are invariably IR-luminous, with IR luminosities exceeding 10^{12} Solar luminosities in all cases. The AGN supplies 76% of the total IR emission, on average, but with a range from 20% to 100%. We find no evidence that the absolute luminosity of obscured star formation is affected by the AGN-driven outflows. Conversely, we find an anticorrelation between the strength of AGN-driven outflows, as measured from the range of outflow velocities over which absorption exceeds a minimal threshold, 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 convincing evidence that this effect is driven by the IR luminosity of the AGN. We conclude that radiatively driven outflows from AGN can have a dramatic, negative impact on luminous star formation in their host galaxies. We find that such outflows act to curtail star formation such that star formation contributes less than ~25% of the total IR luminosity. We also propose that the degree to which termination of star formation takes place is not deducible from the IR luminosity of the AGN.