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Published May 2014 | Supplemental Material + Published + Submitted
Journal Article Open

Variability in Low Ionization Broad Absorption Line outflows


We present results of our time variability studies of Mg ii and Al iii absorption lines in a sample of 22 Low Ionization Broad Absorption Line QSOs (LoBAL QSOs) at 0.2 ≤ z_(em) ≤ 2.1 using the 2-m telescope at IUCAA Girawali Observatory over a time-scale of 10 d to 7.69 years in the QSO's rest frame. Spectra are analysed in conjunction with photometric light curves from Catalina Real-Time Transient Survey. Long time-scale (i.e. ≥1 year) absorption line variability is seen in eight cases (36 per cent systems) while only four of them (i.e. 18 per cent systems) show variability over short time-scales (i.e. <1 year). We notice a tendency of highly variable LoBAL QSOs to have high ejection velocity, low equivalent width and low redshift. The detection rate of variability in LoBAL QSOs showing Fe fine-structure lines (FeLoBAL QSOs) is less than that seen in non-Fe LoBAL QSOs. Absorption line variability is more frequently detected in QSOs having continuum dominated by Fe emission lines compared to rest of the QSOs. Confirming these trends with a bigger sample will give vital clues for understanding the physical distinction between different BAL QSO sub-classes. We correlate the absorption line variability with various parameters derived from continuum light curves and find no clear correlation between continuum flux and absorption line variabilities. However, sources with large absorption line variability also show large variability in their light curves. We also see appearance/disappearance of absorption components in two cases and clear indications for profile variations in four cases. The observed variability can be best explained by a combination of process driven by continuum variations and clouds transiting across the line of sight.

Additional Information

© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. First published online: March 14, 2014. Accepted 2014 February 11. Received 2014 February 6; in original form 2013 October 3. We thank the anonymous referee for a thorough review and helpful comments which led to an improved manuscript. We wish to acknowledge the IUCAA/IGO staff for their support during our observations. RS and PPJ gratefully acknowledge support from the Indo-French Centre for the Promotion of Advanced Research (IFCPAR) under Project N.4304-2. MV gratefully acknowledges IFCPAR for the financial support to visit IAP, Paris. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society and the Higher Education Funding Council for England. The SDSS website is http://www.sdss.org/.

Attached Files

Published - MNRAS-2014-Vivek-799-820.pdf

Submitted - 1402.2980v1.pdf

Supplemental Material - vivek_paper_appendix.pdf


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August 20, 2023
October 26, 2023