The Nature of LoBAL QSOs: I. SEDs and mid-infrared spectral properties

Abstract

We have obtained Spitzer IRS spectra and MIPS 24, 70, and 160 micron photometry for a volume-limited sample of 22 SDSS-selected Low-ionization Broad Absorption Line QSOs (LoBALs) at 0.5 < z < 0.6. By comparing their mid-IR spectral properties and far-IR SEDs with those of a control sample of 35 non-LoBALs matched in M_i, we investigate the differences between the two populations in terms of their infrared emission and star formation activity. Twenty five percent of the LoBALs show PAH features and 45% have weak 9.7 micron silicate dust emission. We model the SEDs and decouple the AGN and starburst contributions to the far-infrared luminosity in LoBALs and in non-LoBALs. Their median total, starburst, and AGN infrared luminosities are comparable. Twenty percent (but no more than 60%) of the LoBALs and 26% of the non-LoBALs are ultra-luminous infrared galaxies (ULIRGs; L_IR>10^12*L_sun). We estimate star formation rates (SFRs) corrected for the AGN contribution to the FIR flux and find that LoBALs have comparable levels of star formation activity to non-LoBALs when considering the entire samples. However, the SFRs of the IR-luminous LoBALs are 80% higher than those of their counterparts in the control sample. The median contribution of star formation to the total far-infrared flux in LoBALs and in non-LoBALs is estimated to be 40-50%, in agreement with previous results for PG QSOs. Overall, our results show that there is no strong evidence from the mid- and far-IR properties that LoBALs are drawn from a different parent population than non-LoBALs.

28 pages, 8 figures, 7 tables; Accepted for publication in ApJ

References in corpus (37)

• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• AGN Dusty Tori: I. Handling of Clumpy Media
• Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: II. Formation of Red Ellipticals
• Mid-IR Galaxy Classification Based on Silicate Obscuration and PAH Equivalent Width
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• The Discovery of 1000 km/s Outflows in Massive Post-starburst Galaxies at z=0.6
• Spitzer Quasar and ULIRG Evolution Study (QUEST): II. The Spectral Energy Distributions of Palomar-Green Quasars
• Integral Field Spectroscopy of Massive, Kiloparsec-Scale Outflows in the Infrared-Luminous QSO Mrk 231
• Spitzer Quasar and ULIRG evolution study (QUEST): I. The origin of the far infrared continuum of QSOs
• A strong redshift dependence of the broad absorption line quasar fraction
• Quasar Outflow Contribution to AGN Feedback: Observations of QSO SDSS J0838+2955
• The Quasar Outflow Contribution to AGN Feedback: VLT Measurements of SDSS J0318-0600
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• Evidence for Merger Remnants in Early-Type Host Galaxies of Low-Redshift QSOs
• Dynamical properties of Ultraluminous Infrared Galaxies. II. Traces of dynamical evolution and end products of local ultraluminous mergers
• The Growth of Massive Black Holes in Galaxy Merger Simulations with Feedback by Radiation Pressure
• Aromatic Features in AGN: Star-Forming Infrared Luminosity Function of AGN Host Galaxies
• The Spitzer View of Low-Metallicity Star Formation: III. Fine Structure Lines, Aromatic Features, and Molecules
• On the 10-micron silicate feature in Active Galactic Nuclei
• The 1-1000 micron SEDs of far-infrared galaxies
• Dense Molecular Gas and the Role of Star Formation in the Host Galaxies of Quasi-Stellar Objects
• Extended silicate dust emission in PG QSOs
• Large amounts of optically-obscured star formation in the host galaxies of some type-2 quasars
• Spectacular Shells in the Host Galaxy of the QSO MC2 1635+119
• Radio Through X-ray Spectral Energy Distributions of 38 Broad Absorption Line Quasars
• Evidence that FeLoBALs may signify the transition between an ultraluminous infrared galaxy and a quasar
• Distance to Multiple Kinematic Components of Quasar Outflows: VLT Observations of QSO 2359-1241 and SDSS J0318-0600
• Radio spectra and polarisation properties of radio-loud Broad Absorption Line Quasars
• Evidence for 1000 km/s Molecular Outflows in the Local ULIRG Population
• Spectropolarimetry of PKS 0040-005 and the Orientation of Broad Absorption Line Quasars
• The Viewing Angles of Broad Absorption Line Versus Unabsorbed Quasars
• An Infrared Comparison of Type-1 and Type-2 Quasars
• The extraordinary mid-infrared spectral properties of FeLoBAL Quasars
• On the dust geometry in radio-loud active galactic nuclei
• Spectropolarimetry of Radio-Selected Broad Absorption Line Quasars

Cited by in corpus (18)

• Weak Hard X-ray Emission from Two Broad Absorption Line Quasars Observed with NuSTAR: Compton-thick Absorption or Intrinsic X-ray Weakness?
• On the structure and energetics of quasar broad absorption-line outflows
• The average absorption properties of broad absorption line quasars at 800 < lambda_rest < 3000 Å, and the underlying physical parameters
• Stratified disc wind models for the AGN broad-line region: ultraviolet, optical and X-ray properties
• The Intrinsic Fractions and Radio Properties of Low Ionization Broad Absorption Line Quasars
• The z=0.54 LoBAL Quasar SDSS J085053.12+445122.5: I. Spectral Synthesis Analysis Reveals a Massive Outflow
• Variability in Low Ionization Broad Absorption Line Outflows
• Near-IR spectroscopy of luminous LoBAL quasars at 1<z<2.5
• Stronger Constraints on the Evolution of the $M_{\mathrm{BH}}-{\sigma }_{\ast }$ Relation up to $z\sim 0.6$
• Herschel-ATLAS: the far-infrared properties and star-formation rates of broad absorption line quasi-stellar objects
• Discovery of strong Balmer line absorption in two luminous LoBAL quasars at z~1.5
• An Infrared Excess Identified in Radio-Loud Broad Absorption Line Quasars
• Broad-band spectral energy distribution of 3000 Angstroem break quasars from the Sloan Digital Sky Survey
• Evidence for Fluorescent Fe II Emission from Extended Low Ionization Outflows in Obscured Quasars
• Redshifted broad absorption line quasars found via machine-learned spectral similarity
• The X-ray Spectrum and Spectral Energy Distribution of FIRST J155633.8+351758: a LoBAL Quasar with a Probable Polar Outflow
• The Nature of LoBAL QSOs: II. HST/WFC3 Observations Reveal Host Galaxies Dominated by Mergers
• Near-infrared spectroscopy of extreme BAL QSOs from the QUBRICS bright quasar survey