Astronomy and Astrophysics – Astrophysics
Scientific paper
1995-12-06
Astronomy and Astrophysics
Astrophysics
10 pages, no figures, AAS latex (aaspptwo.sty), to be published in ApJ Vol. 462, May 20 1996
Scientific paper
10.1086/177178
Recent results from the ROSAT All-Sky Survey (RASS) have shown that broad absorption line (BAL) QSOs are either highly absorbed or underluminous in the soft X-ray bandpass. Here, we extend this work by analyzing all known bona fide BALQSOs observed within the inner 20' of the ROSAT PSPC. This sample includes both targeted and serendipitous exposures ranging from 8 to 75 ksec. Despite these deep exposures, most of the BALQSOs are undetected, and have unusually weak X-ray emission, as evidenced by large optical-to-X-ray slopes (AOX). Large values of AOX ($\gapprox$1.8) may prove to be a defining characteristic of BALQSOs. We predict that samples of QSO candidates with large AOX will yield a higher percentage of BALQSOs, particularly at low redshift. As a corollary, X-ray-selected QSO samples should yield The optical/UV emission line spectra of BAL and non-BAL QSOs are quite similar, suggesting that their intrinsic spectral energy distributions are similar as well. Absorption thus seems the likely reason for the X-ray quiet nature of BALQSOs. To constrain the total absorbing column of the BAL clouds, we compare our measured soft X-ray fluxes or upper limits to those expected from normal radio quiet QSOs of comparable optical continuum magnitude and redshift. From sensitive X-ray observations, we derive column densities of greater than about 2 times 10^22 cm-2, for intrinsic cold absorbers of solar metallicity. These new results suggest columns {\em at least} an order of magnitude larger than the columns previously estimated from optical/UV spectra alone.
Green Paul J.
Mathur Smita
No associations
LandOfFree
Broad Absorption Line QSOs Observed by the ROSAT PSPC does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Broad Absorption Line QSOs Observed by the ROSAT PSPC, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Broad Absorption Line QSOs Observed by the ROSAT PSPC will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-90406