Direct Measurement of Quasar Outflow Wind Acceleration

Abstract

We search for velocity changes (i.e., acceleration/deceleration) of narrow absorption lines (NALs) that are intrinsic to the quasars, using spectra of 6 bright quasars that have been observed more than once with 8-10m class telescopes. While variations in line strength and profile are frequently reported (especially in broader absorption lines), definitive evidence for velocity shifts has not been found with only a few exceptions. Direct velocity shift measurements are valuable constraints on the acceleration mechanisms. In this study, we determine velocity shifts by comparing the absorption profiles of NALs at two epochs separated by more than 10 years in the observed frame, using the cross-correlation function method and we estimate the uncertainties using Monte Carlo simulations. We do not detect any significant shifts but we obtain 3$\sigma$ upper limits on the acceleration of intrinsic NALs (compared to intervening NALs in same quasars) of $\sim$0.7 km s${}^{-1}$ yr${}^{-1}$ ($\sim$0.002 cm s${}^{-2}$). We discuss possible scenarios for non-detection of NAL acceleration/deceleration and examine resulting constraints on the physical conditions in accretion disk wind.

25 pages, including 6 figures; submitted to the Astrophysical Journal

References in corpus (11)

• A Catalog of Quasar Properties from SDSS DR7
• Cosmic dynamics in the era of Extremely Large Telescopes
• Quasar Broad Absorption Line Variability on Multi-Year Time Scales
• A Census of Intrinsic Narrow Absorption Lines in the Spectra of Quasars at z=2-4
• Tombaugh 2: The First Open Cluster with a Significant Abundance Spread or Embedded in a Cold Stellar Stream?
• The UVES Large Program for testing fundamental physics - III. Constraints on the fine-structure constant from 3 telescopes
• The time evolution of cosmological redshift as a test of dark energy
• CIV Broad Absorption Line Acceleration in Sloan Digital Sky Survey Quasars
• Acceleration and Substructure Constraints in a Quasar Outflow
• Evolutive Unification in Composite Active Galactic Nuclei
• Monitoring the Variability of Intrinsic Absorption Lines in Quasar Spectra

Cited by in corpus (2)

• HST/COS Observations of Quasar Outflows in the 500 -- 1050 Å Rest Frame: IV. The Largest Broad Absorption Line Acceleration
• A Kinematic Shift of the C IV Broad Absorption Line in Quasar SDSS J120819.29+035559.4