Spitzer Space Telescope - General Observer Proposal #50792


The nature of low-ionization BAL QSOs

Principal Investigator: Gabriela Canalizo
           Institution: University of California, Riverside

     Technical Contact: Gabriela Canalizo, University of California, Riverside

Co-Investigators: 
Mariana Lazarova, University of Califonia, Riverside                  
Mark Lacy, Spitzer Science Center                                     

Science Category: AGN/quasars/radio galaxies 
 Observing Modes: IrsStare MipsPhot 
  Hours Approved: 16.4 

Abstract:
The rare subclass of optically-selected QSOs known as low-ionization broad
absorption line (LoBAL) QSOs show show signs of high-velocity gas outflows and
reddened continua indicative of dust obscuration. Recent studies show that
galaxies hosting LoBAL QSOs tend to be ultraluminous infrared systems that are
undergoing mergers and that have young (< 100 Myr) stellar populations. Such
observations support the idea that LoBAL QSOs represent a short-lived phase
early in the life of QSOs, when powerful AGN-driven winds are blowing away the
dust surrounding the QSO. If so, understanding LoBALs may be crucial in the
study of phenomena regulating black hole and galaxy evolution, such as AGN
feedback and the early stages of nuclear accretion. Such claims, however, are
based on results from very small samples that may have serious selection biases.
We are therefore taking a more aggressive approach by conducting a systematic
study of a volume limited sample of LoBAL QSOs at 0.5 < z < 0.6 drawn from SDSS.
We propose to obtain far-IR fluxes with MIPS to construct SEDs for these objects
and determine whether they are truly exclusively found in ultraluminous infrared
systems. We also propose to obtain IRS spectra to estimate star formation rates
from PAH features.