Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Table of Contents
· Reads History
·
· Translate This Page
Title:
Testing the Radiative-Driving Hypothesis of Quasar Outflows
Authors:
Stark, Michele A.; Ganguly, R.; Gallagher, S. C.; Gibson, R.; Brotherton, M. S.
Affiliation:
AA(University of Michigan - Flint), AB(University of Michigan - Flint), AC(University of Western Ontario, Canada), AD(University of Washington), AE(University of Wyoming)
Publication:
American Astronomical Society, AAS Meeting #217, id.142.03; Bulletin of the American Astronomical Society, Vol. 43, 2011
Publication Date:
01/2011
Origin:
AAS
Abstract Copyright:
(c) 2011: American Astronomical Society
Bibliographic Code:
2011AAS...21714203S

Abstract

Outflows are seen prominently in the UV spectra of Broad Absorption Line (BAL) QSOs. Models of radiatively-driven outflows predict that the velocity should scale with UV luminosity. Observations show that the UV luminosity only provides a cap to the velocity. One explanation is that the X-ray absorbing gas in an individual quasar provides a shield that improves its radiative-driving efficiency. That is, quasars with thick shields can accelerate gas to higher velocity. X-ray observations of BALQSOs support this in the sense that BALQSOs with more soft X-ray absorption tend to have higher velocity outflows. But there is much scatter in this trend, making the underlying physics difficult to extract. To combat this, we conducted an experiment using exploratory Chandra-ACIS observations of 12 carefully-selected z=1.7-2.0 BALQSOs. These BALQSOs were chosen to have very narrow ranges in (1) UV luminosity, (2) UV spectral shape, and (3) absorption velocity width. Within this otherwise uniform sample, the outflow velocities range from 4500km/s to 18000km/s, a factor of four. All objects are detected in the full band (0.5-8keV), with count rates in the range (0.5-5)e-3 cps, and have hardness ratios in the range -0.6 to 0.3. We compare the X-ray brightnesses and spectral shapes of our sample with those of more diverse samples of BALQSOs.

We gratefully acknowledge support through Chandra grant GO9-0120X.

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
  New!

Find Similar Abstracts:

Use: Authors
Title
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints