J/MNRAS/473/5154 Strong MgII absorber blazars (Mishra+, 2018)
On the incidence of Mg II absorbers along the blazar sightlines.
Mishra S., Chand H., Gopal-Krishna, Joshi R., Shchekinov Y.A.,
Fatkhullin T.A.
<Mon. Not. R. Astron. Soc., 473, 5154-5164 (2018)>
=2018MNRAS.473.5154M 2018MNRAS.473.5154M (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; QSOs ; Redshifts ;
Equivalent widths
Keywords: galaxies: active - BL Lacertae objects: general - galaxies: jet -
galaxies: photometry - quasars: emission lines - quasars: general
Abstract:
It is widely believed that the cool gas clouds traced by MgII
absorption, within a velocity offset of 5000km/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. (2011A&A...525A..61P 2011A&A...525A..61P, 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 two
times the expectation based on the MgII 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-a-vis normal QSOs. We have also assembled an
approximately 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 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 up to offset speeds
{DELTA}v∼0.2c relative to the blazar.
Description:
The blazar sample employed in our analysis is an amalgamation of three
sets of blazars extracted from the catalogues published by Massaro et
al. (2009, Cat. J/A+A/495/691, hereafter ROMA-BZCAT), Veron-Cetty &
Veron (2010A&A...518A..10V 2010A&A...518A..10V, cat. VII/258, hereafter VV) and Padovani
& Giommi (1995, Cat. J/MNRAS/277/1477, hereafter Padovani-Catalogue).
We are led to a final sample of 191 blazars for the strong MgII
absorber case.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 46 191 Basic properties of our sample of 191 blazars
table3.dat 124 43 The detected 43 MgII absorption systems and
their rest-frame equivalent widths,
Wr(MgIIλ2796Å), as identified in 35
blazars belonging to our sample of 191 blazars
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See also:
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
J/MNRAS/277/1477 : A catalogue of BL Lacertae objects (Padovani+ 1995)
J/A+A/495/691 : Blazars multifrequency catalog, Roma-BZCAT (Massaro+, 2009)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Blazar Blazar name (JHHMMSS+DDMMSS)
15 A1 --- n_z [*] Note on z (1)
17- 21 F5.3 --- z Emission redshift (1)
24- 32 A9 --- Source Archive name from where data has been aquired
35- 39 F5.3 --- Deltaz Redshift path for strong system analysis (2)
42- 46 F5.1 --- SNR SNR of the spectrum involved in the analysis
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Note (1): asterisk indicates sources that do not have emission redshift
measurement for which we have taken lower limit based on the most redshifted
MgII absorber seen in their spectra.
Note (2): The redshift path contribution to the strong MgII system
(Wr(2796)>1.0Å) analysis..
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Blazar Blazar name (JHHMMSS+DDMMSS)
17- 21 F5.3 --- zem Emission redshift
24- 30 F7.5 --- zabs Absorption redshift of detected MgII system
33- 38 F6.4 0.1nm Wr Equivalent width of detected MgII system
41-124 A84 --- Abs Associated metal absorption lines detected
using the velocity plot w.r.t absorption
redshift of MgII systems
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jan-2021