On the incidence of MgII absorbers along the blazar sightlines
arXiv:1710.04020 · doi:10.1093/mnras/stx2684
Abstract
It is widely believed that the cool gas clouds traced by MgII absorption, within a velocity offset of 5000 km/s 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. (2011, hereinafter BBM) has seriously questioned this paradigm, by showing that the number density of intervening MgII absorbers towards the 45 blazars in their sample is nearly 2 times the expectation based on the MgII absorption systems seen towards normal 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-a-vis normal QSOs. We have also assembled a ~3 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 MgII 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 upto offset speeds Δv ~0.2c relative to the blazar.
arXiv comment12 pages, 6 figures, 7 tables, accepted for publication in MNRAS
References in corpus (17)
- Damped Lyman alpha Systems
- Roma-BZCAT: A multifrequency catalogue of Blazars
- Evidence for ultra-fast outflows in radio-quiet AGNs: II - detailed photo-ionization modeling of Fe K-shell absorption lines
- Probing the cosmological variation of the fine-structure constant: Results based on VLT-UVES sample
- Mg II Absorption Systems in SDSS QSO Spectra
- The JHU-SDSS metal absorption line catalog: redshift evolution and properties of Mg II absorbers
- A Sample-oriented Catalogue of BL Lacertae Objects
- On the Incidence of Strong MgII Absorbers Along GRB Sightlines
- Statistics and characteristics of MgII absorbers along GRB lines of sight observed with VLT-UVES
- An Excess of Mg II Absorbers in BL Lac Objects
- Intervening Metal Systems in GRB and QSO sight-lines: The Mgii and Civ Question
- Casting light on the 'anomalous' statistics of Mg II absorbers toward Gamma-Ray Burst afterglows: the incidence of weak systems
- Incidence of MgII absorbers towards Blazars and the GRB/QSO puzzle
- Testing the Possible Intrinsic Origin of the Excess of Very Strong MgII Absorbers Along GRB Lines-of-Sight
- An Independent Measurement of the Incidence of MgII Absorbers along Gamma-Ray Burst Sightlines: the End of the Mystery?
- Incidence of Mg II absorption systems towards flat-spectrum radio quasars
- Incidence of Strong MgII Absorbers Towards Different Types of Quasars
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- The Detection Rate of Associated \mgii\ Absorption Lines in Quasars Depends on Their Radio Emission
- Circumgalactic medium of quasar host galaxies at 0.4<z<0.8 probed by strong Mg II absorption
- Distance estimation of gamma-ray emitting BL Lac objects from imaging observations