The dependence of C IV broad absorption line properties on accompanying Si IV and al III absorption: Relating quasar-wind ionization levels, kinematics, and column densities

N. Filiz Ak, W. N. Brandt, P. B. Hall, D. P. Schneider, J. R. Trump, S. F. Anderson, F. Hamann, Adam D. Myers, I. Pâris, P. Petitjean, Nicholas P. Ross, Yue Shen, Don York

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

We consider how the profile and multi-year variability properties of a large sample of C IV Broad Absorption Line (BAL) troughs change when BALs from Si IV and/or Al III are present at corresponding velocities, indicating that the line of sight intercepts at least some lower ionization gas. We derive a number of observational results for C IV BALs separated according to the presence or absence of accompanying lower ionization transitions, including measurements of composite profile shapes, equivalent width (EW), characteristic velocities, composite variation profiles, and EW variability. We also measure the correlations between EW and fractional-EW variability for C IV, Si IV, and Al III. Our measurements reveal the basic correlated changes between ionization level, kinematics, and column density expected in accretion-disk wind models; e.g., lines of sight including lower ionization material generally show deeper and broader C IV troughs that have smaller minimum velocities and that are less variable. Many C IV BALs with no accompanying Si IV or Al III BALs may have only mild or no saturation.

Original languageEnglish (US)
Article number88
JournalAstrophysical Journal
Volume791
Issue number2
DOIs
StatePublished - Aug 20 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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