The Energetics of Quasar Broad Absorption Line Outflows
Abstract
Broad absorption lines (BALs) in quasar spectra identify high velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution. In order to determine the viability of these outflows as a feedback mechanism, we need estimates of their mass outflow rates and kinetic energy yields. These quantities depend on the column densities of the flows, which are difficult to obtain directly from spectra of the BALs. To address this problem, we turn to a low-abundance species, PV λ1118, 1128. Phosphorus is much less abundant than, for example, carbon (about 1000 times less abundant in the Sun), so a detection of a PV BAL indicates that other lines, such as the well-studied CIV λ1550 BAL, are saturated. We detect variability in a PV BAL in Q1413+1143, corresponding to variable SiIV λ1400 and CIV BALs. The variability in the PV BAL confirms that the absorption is intrinsic to the quasar and provides a constraint on the location of the gas. Using the apparent optical depth of the PV BAL and photoionization models, we can constrain the true column density of the outflow. With constraints on the location and column density, we estimate the kinetic energy yields and compare to simulations to estimate the viability of the outflow as a feedback mechanism. We also search through archival data to estimate the overall incidence of PV absorption in BAL quasar spectra.
- Publication:
-
American Astronomical Society Meeting Abstracts #220
- Pub Date:
- May 2012
- Bibcode:
- 2012AAS...22033515C