Monitoring Emergent Absorption Troughs in Quasars
Abstract
Outflows from luminous active galactic nuclei --- quasars --- are important ingredients in galaxy formation and the enrichment of the intergalactic medium. These outflows can manifest as broad absorption line (BAL) troughs in quasar spectra. Trough variability can be used to constrain the physical parameters of these absorbing structures through comparison to models and simulations of accretion disk winds. Monitoring appearing and disappearing BAL troughs can constrain the distribution of BAL trough lifetimes along our line of sight. By comparing repeat quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and the original SDSS, we have identified 68 quasars in whose spectra new absorption troughs have appeared between the two surveys (over 300-1200 rest frame days), including a rare trough at 60,000 km/s outflow velocity. We propose GMOS spectroscopy of 56 of the brightest of these quasars to measure the absorption strength in newly appeared troughs 200-300 rest-frame days after their first measurement. We expect that some troughs will still be growing in strength, but even a failure to detect a statistical increase in absorption strength in our sample would be useful. That could indicate a rapid onset of absorption from fast-moving, sharp-edged absorbing structures, which simulations would have to match.
- Publication:
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NOAO Proposal
- Pub Date:
- February 2013
- Bibcode:
- 2013noao.prop..544H