Star Formation in Luminous LoBAL Quasars at 2.0<z<2.5

TL;DR

This study investigates luminous LoBAL quasars at redshifts 2.0-2.5, revealing high star formation rates and supporting their evolutionary link to starburst activity, with evidence of enhanced star formation compared to other quasar types.

Contribution

It provides new FIR observations and spectral data for a sample of LoBAL quasars, demonstrating their high star formation rates and evolutionary significance.

Findings

LoBALs exhibit star formation rates of 740-2380 M_sun/yr.

LoBALs show higher SFRs compared to HiBAL and non-BAL quasars.

LoBAL environments are similar to the general galaxy population at similar redshifts.

Abstract

Low-ionisation broad absorption line quasars (LoBALs) mark an important, yet poorly understood, population of quasars showing direct evidence for energetic mass outflows. We outline a sample of 12 luminous (L$_{\rm{bol}}$ $>$10$^{46}$ergs$^{-1}$) LoBALs at 2.0$<$z$<$2.5 - a key epoch in both star formation and black hole accretion, which have been imaged as part of a targeted program with the \textit{Herschel} Spectral and Photometric Imaging REceiver (SPIRE). We present K-band NOTCam spectra for three of these targets, calculating their spectroscopic redshifts, black hole masses and bolometric luminosities, and increasing the total number of LoBAL targets in our sample with spectral information from five to eight. Based on FIR obeservations from \textit{Herschel} SPIRE, we derive prolific SFRs ranging 740 - 2380M$_{\rm{\odot}}$yr$^{-1}$ for the detected targets, consistent with LoBALs existing in an evolutionary phase associated with starburst activity. Furthermore, an upper limit of $<$440M$_{\rm{\odot}}$yr$^{-1}$ is derived for the non-detections, meaning moderate-to-high SFRs cannot be ruled out, even among the undetected targets. Indeed, we detect an enhancement in both the SFRs and FIR fluxes of LoBALs compared to HiBAL and non-BAL quasars, further supporting the evolutionary LoBAL paradigm. Despite this enhancement in SFR however, the environments of LoBALs appear entirely consistent with the general galaxy population at 2.0$<$z$<$2.5.