2008/07/29 by Z. Y. Zheng, J. X. Wang
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/592141
16 pages, 4 figures, ApJ accepted
arxiv created 2008/07/29 · openalex publication_date 2008/11/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
In this paper, we provide new 1 Ms Chandra ACIS spectra of two quasars in the Chandra Deep Field South (CDF-S), which were previously reported to show strong and extremely blueshifted X-ray emission/absorption line features in previous 1 Ms spectra, with outflowing bulk velocity v∼0.65-0.84c. In the new 1 Ms spectra, the relativistic blueshifted line feature is solidly confirmed in CXO CDFS J033225.3-274219 (CDFS 46, z = 1.617), and marginally visible in CXO CDFS J033260.0-274748 (CDFS 11, z = 2.579), probably due to the increased Chandra ACIS background in the new 1 Ms exposure. The new data rule out the possibility (though very tiny already based on the old 1Ms data) that the two sources were selected to be unusual due to noise spikes in the spectra. The only likely interpretation is extremely blueshifted iron absorption/emission line or absorption edge due to relativistic outflow. We find that the rest frame emission line center in CDFS 46 marginally decreased from 16.2 keV to 15.2 keV after 7 years. The line shift can be due to either decreasing outflowing velocity or lower ionization level. Including the two quasars reported in this paper, we collect from literature a total of 7 quasars showing blueshifted emission or absorption line feature with v≥0.4c in X-ray spectra, and discuss its connection to jet and/or BAL (broad absorption line) outflow.