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http://hdl.handle.net/2289/6904
Title: | On the incidence of Mg II absorbers along the blazar sightlines |
Authors: | Mishra S, S. Chand, Hum Gopal-Krishna Joshi, R. Shchekinov, Yuri Fatkhullin, T.A. |
Keywords: | BL Lacertae objects photometry quasars emission lines |
Issue Date: | Feb-2018 |
Publisher: | Oxford University Press for the Royal Astronomical Society |
Citation: | Monthly Notices of the Royal Astronomical Society, 2018, Vol. 473, P5154-5164 |
Abstract: | It is widely believed that the cool gas clouds traced by Mg ii absorption, within a velocity offset of 5000 km s−1 relative to the background quasar are mostly associated with the quasar itself, whereas the absorbers seen at larger velocity offsets towards us are intervening absorber systems and hence their existence is completely independent of the background quasar. Recent evidence by Bergeron et al. (hereinafter BBM) has seriously questioned this paradigm, by showing that the number density of intervening Mg ii absorbers towards the 45 blazars in their sample is nearly two times the expectation based on the Mg ii absorption systems seen towards normal quasars (QSOs). Given its serious implications, it becomes important to revisit this finding, by enlarging the blazar sample and subjecting it to an independent analysis. Here, we first report the outcome of our re-analysis of the available spectroscopic data for the BBM sample itself. Our analysis of the BBM sample reproduces their claimed factor of 2 excess of dN/dz along blazar sightlines, vis-à-vis normal QSOs. We have also assembled an approxmately three times larger sample of blazars, albeit with moderately sensitive optical spectra. Using this sample together with the BBM sample, our analysis shows that the dN/dz of the Mg ii absorbers statistically matches that known for normal QSO sightlines. Further, the analysis indicates that associated absorbers might be contributing significantly to the estimated dN/dz up to offset speeds Δv ∼ 0.2c relative to the blazar. |
Description: | Open Access |
URI: | http://hdl.handle.net/2289/6904 |
ISSN: | 0035-8711 1365-2966 - (online) |
Alternative Location: | http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1710.04020 https://arxiv.org/abs/1710.04020 http://dx.doi.org/10.1093/mnras/stx2684 |
Copyright: | 2018 The authors & the Royal Astronomical Society |
Appears in Collections: | Research Papers (A&A) |
Files in This Item:
File | Description | Size | Format | |
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2018_MNRAS_473_5154.pdf | Open Access | 943.7 kB | Adobe PDF | View/Open |
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