BAL and non-BAL quasars: Continuum, emission, and absorption properties establish a common parent sample


Type
Article
Change log
Authors
Rankine, AL 
Hewett, PC 
Richards, GT 
Abstract

Using a sample of $\simeq$144,000 quasars from the Sloan Digital Sky Survey data release 14 we investigate the outflow properties, evident both in absorption and emission, of high-ionization Broad Absorption Line (BAL) and non-BAL quasars with redshifts 1.6 z 3.5 and luminosities 45.3 $< \log_{10}(L_{bol}) < $ 48.2 erg s−1. Key to the investigation is a continuum and emission-line reconstruction scheme, based on mean-field independent component analysis, that allows the kinematic properties of the CIV$\lambda1550emissionlinetobecompareddirectlyforbothnonBALandBALquasars.CIVemissionblueshiftandequivalentwidth(EW)measurementsarethusavailableforbothpopulations.ComparisonsoftheemissionlineandBALtroughpropertiesrevealstrongsystematiccorrelationsbetweentheemissionandabsorptionproperties.ThedependenceofquantitativeoutflowindicatorsonphysicalpropertiessuchasquasarluminosityandluminosityrelativetoEddingtonluminosityarealsoshowntobeessentiallyidenticalfortheBALandnonBALpopulations.ThereisanabsenceofBALsinquasarswiththehardestspectralenergydistributions(SEDs),revealedbythepresenceofstrongHeII\lambda1640emission,largeCIV\lambda$1550-emission EW and no measurable blueshift. In the remainder of the CIV-emission blueshift versus EW space, BAL and non-BAL quasars are present at all locations; for every BAL-quasar it is possible to identify non-BAL quasars with the same emission-line outflow properties and SED-hardness. The co-location of BAL and non-BAL quasars as a function of emission-line outflow and physical properties is the key result of our investigation, demonstrating that (high-ionization) BALs and non-BALs represent different views of the same underlying quasar population.

Description
Keywords
line: profiles, quasars: absorption lines, quasars: emission lines, quasars: general
Journal Title
Monthly Notices of the Royal Astronomical Society
Conference Name
Journal ISSN
0035-8711
1365-2966
Volume Title
Publisher
Oxford University Press (OUP)
Rights
All rights reserved
Sponsorship
Science and Technology Facilities Council (ST/N000927/1)