2008/02/02 by Junxian Wang, Peng Jiang, Hongyan Zhou +3 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/586893
11 pages, including 2 figures, ApJ letter accepted
arxiv created 2008/02/02 · openalex publication_date 2008/03/11 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We have selected a sample of broad absorption line (BAL) quasars which show significant radio variations, indicating the presence of polar BAL outflows. We obtained snapshot XMM observations of four polar BAL QSOs, to check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exists in polar outflows. Two of the sources are detected in the X-ray. Spectral fittings show that they are X-ray normal with no intrinsic X-ray absorption, suggesting the X-ray shielding gas might be absent in polar BAL outflows. Comparing to non-BAL QSOs, one of two X-ray-nondetected sources remains consistent with X-ray normal, while the other one, which is an iron low-ionization BAL (FeLoBAL), shows an X-ray weakness factor of >19, suggesting strong intrinsic X-ray absorption. Alternative explanations for the nondetection of strong X-ray absorption in the two X-ray-detected sources are that (1) the absorption is more complex than a simple neutral absorber, such as partial covering absorption or ionized absorption; (2) there might be significant jet contribution to the detected X-ray emission. Current data are insufficient to test these possibilities, and further observations are required to understand the X-ray nature of polar BAL outflows.