Evidence that FeLoBALs may signify the transition between an ultraluminous infrared galaxy and a quasar

TL;DR

This study shows that FeLoBAL quasars are associated with galaxies undergoing intense starbursts and rapid black hole growth, indicating a transitional evolutionary phase between ultraluminous infrared galaxies and quasars.

Contribution

It provides infrared observations of FeLoBAL QSOs and proposes they mark a key transitional stage in galaxy and black hole evolution.

Findings

FeLoBALs are extremely luminous in the infrared, similar to ULIRGs.

Star formation rates in these objects are several hundred solar masses per year.

FeLoBAL signatures can identify galaxies in a critical evolutionary phase.

Abstract

We present mid/far-infrared photometry of nine FeLoBAL QSOs, taken using the Spitzer space telescope. All nine objects are extremely bright in the infrared, with rest-frame 1-1000 micron luminosities comparable to those of Ultraluminous Infrared Galaxies. Furthermore, a significant fraction of the infrared emission from many, and possibly all of the sample is likely to arise from star formation, with star formation rates of order several hundred solar masses per year. We combine these results with previous work to propose that FeLoBALs mark galaxies and QSOs in which an extremely luminous starburst is approaching its end, and in which a rapidly accreting supermassive black hole is in the last stages of casting off its dust cocoon. FeLoBAL signatures in high redshift QSOs and galaxies may thus be an efficient way of selecting sources at a critical point in their evolution.