Quasar Absorption Lines from Radiative Shocks: Implications for Multiphase Outflows and Feedback

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Photoionization modeling of certain low-ionization broad absorption lines in quasars implies very compact (ΔR ∼0.01 pc), galaxy-scale (R∼ kpc) absorbers blueshifted by several 1000 km s-1. While these are likely signatures of quasar outflows, the lifetimes of such compact absorbers are too short for them to be direct ejecta from a nuclear wind. Instead, I argue that the absorbing clouds must be transient and created in situ. Following arguments detailed by Faucher-Giguère, Quataert, & Murray (2011), I show that a model in which the cool absorbers form in radiative shocks arising when a quasar blast wave impacts an interstellar cloud along the line of sight successfully explains the key observed properties. Using this radiative shock model, the outflow kinetic luminosities for three luminous quasars are estimated to be Ėk ≈ 2–5% LAGN (with corresponding momentum fluxes Ṗ ≈2–15 LAGN/c), consistent with feedback models of the M–σ relation. These energetics are similar to those recently inferred of molecular outflows in local ultra-luminous infrared galaxies and in post-starburt winds, suggesting that active galactic nuclei (AGN) are capable of driving such outflows. Radiative shocks probably affect the multiphase structure of outflows in a range of other systems, potentially including narrower and higher-ionization quasar absorption lines, and compact intergalactic absorbers ejected by star formation and/or AGN activity.
Original languageEnglish (US)
Title of host publicationAGN Winds in Charleston
Subtitle of host publicationProceedings of a Conference Held at the College of Charleston, Charleston, South Carolina, USA
EditorsGeorge A Chartas, Frederick W Hamann, Karen M Leighly
PublisherAstronomical Society of the Pacific
Number of pages5
ISBN (Electronic)971-1-58381-803-9
ISBN (Print)978-1583818022
StatePublished - 2012

Publication series

NameAstronomical Society of the Pacific conference series


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