X-RAY INSIGHTS INTO THE PHYSICS OF MINI-BAL QUASAR OUTFLOWS
- Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)
We examine the ultraviolet and X-ray properties of 256 radio-quiet Sloan Digital Sky Survey quasars (QSOs) observed in X-rays with Chandra and/or XMM-Newton in order to study the relationship between QSOs with broad C IV absorption lines (BALs; width >2000 km s{sup -1}) and those with C IV mini-BALs (here defined to have widths of 1000-2000 km s{sup -1}). Our sample includes 42 BAL and 48 mini-BAL QSOs. The relative X-ray brightness and hard spectral slopes of the mini-BAL population are, on average, intermediate between those of BAL and non-BAL QSOs, as might be expected if narrower and broader absorption line outflows are physically related. However, a significant population of mini-BALs has outflow velocities higher than would be expected for BAL QSOs of the same relative X-ray brightness. Consistently strong X-ray absorption is apparently not required to accelerate at least some mini-BALs to high outflow velocities. Assuming the mini-BAL features are correctly attributed to intrinsic C IV absorption, we suggest that their observed properties may be explained if mini-BALs are 'seeds' that can be accelerated to form BALs when sufficient X-ray shielding is present. We also examine several QSOs with broad C IV absorption that have been recently reported to be unusually X-ray bright. Such cases are frequently mini-BAL QSOs, which, as a population, are generally brighter in X-rays than BAL QSOs. Pointed XMM-Newton observations also suggest that these sources (or unresolved neighbors) may have been previously observed in a high-flux state.
- OSTI ID:
- 21296176
- Journal Information:
- Astrophysical Journal, Vol. 696, Issue 1; Other Information: DOI: 10.1088/0004-637X/696/1/924; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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