J/ApJ/890/132 MgII abs. toward SDSS QSOs with rotation measures (Malik+, 2020)
Role of intervening Mg II absorbers on the rotation measure and fractional
polarization of the background quasars.
Malik S., Chand H., Seshadri T.R.
<Astrophys. J., 890, 132-132 (2020)>
=2020ApJ...890..132M 2020ApJ...890..132M (SIMBAD/NED BibCode)
ADC_Keywords: QSOs; Polarization; Redshifts; Equivalent widths; Spectra, optical
Keywords: Magnetic Fields; Rotation Measure; Quasars; Mg II Absorber; Galaxy
Abstract:
We probed the magnetic fields in high-redshift galaxies using excess
extragalactic contribution to residual rotation measure (RRM) for
quasar sightlines with intervening MgII absorbers. Based on a large
sample of 1132 quasars, we have computed RRM distributions broadening
using median absolute deviation from the mean (σrrmmd), and
found it to be 17.1±0.7rad/m2 for 352 sightlines having MgII
intervening absorbers in comparison to its value of 15.1±0.6rad/m2
for 780 sightlines without such absorbers, resulting in an excess
broadening (σrrmex) of 8.0±1.9rad:m2 among these two
subsamples. This value of σrrmex, has allowed us to
constrain the average strength of magnetic field (rest frame) in
high-redshift galaxies responsible for these Mg II absorbers, to be
∼1.3±0.3µG at a median redshift of 0.92. This estimate of
magnetic field is consistent with the reported estimate in earlier
studies based on radio-infrared correlation and energy equipartition
for galaxies in the local universe. A similar analysis on subsample
split based on the radio spectral index, α (with
Fν∝να), for flat (α≥-0.3; 315 sources)
and steep (α≤-0.7; 476 sources) spectrum sources shows a
significant σrrmex (at 3.5σ level) for the former and
absent in the latter. An anticorrelation found between the
σrrmmd and percentage polarization (p) with a similar
Pearson correlation of -0.62 and -0.87 for subsamples with and without
MgII, respectively, suggests the main contribution for decrements in
the p value to be intrinsic to the local environment of quasars.
Description:
For rotation measurements of quasars, we have used the catalog of
Taylor+ (TSS09; 2009, J/ApJ/702/1230) consisting of RM values for
37543 sources based on NVSS observations. In the catalog they used Q
and U Stokes parameters in two frequency bands, 1.36 and 1.43GHz, to
estimate the polarized intensity and percentage polarization.
For searching the optical counterpart of the quasars listed in TSS09,
we have used SDSS DR-7, 9, 12, and 14 catalogs of quasars for their
optical spectra.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 75 1132 Main properties of our 1132 quasars sample (after
discounting 3 outliers being at 9σ level)
table3.dat 37 442 Main properties of our 442 MgII absorption systems
seen towards 352 quasars sightlines in our sample
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See also:
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VII/289 : SDSS quasar catalog, sixteenth data release (DR16Q) (Lyke+, 2020)
J/AJ/106/848 : QSO MgII absorption line systems (Drinkwater+, 1993)
J/A+A/410/33 : MgII/FeII absorbers in 2dF-quasar survey (Menard+, 2003)
J/ApJ/702/1230 : Rotation measure image of the sky (Taylor+, 2009)
J/ApJS/194/42 : SDSS-DR3 MgII-based black hole masses (Rafiee+, 2011)
J/A+A/546/A67 : Catalog of strong MgII absorbers (Lawther+, 2012)
J/ApJ/748/131 : MgII absorbers in SDSS-DR7 quasar catalog (Shen+, 2012)
J/ApJ/754/38 : MgII abs. syst. for Flat-Spectrum Radio QSOs (Chand+, 2012)
J/ApJ/779/161 : MgII absorbers in 0.4<z<2.3 SDSS QSOs (Seyffert+, 2013)
J/ApJS/212/15 : Polarized NVSS sources SEDs (Farnes+, 2014)
J/MNRAS/442/3329 : Rotation measures of 2642 quasars (Xu+, 2014)
J/ApJ/795/63 : Faraday rotation from magnesium II absorbers (Farnes+, 2014)
J/MNRAS/473/5154 : Strong MgII absorber blazars (Mishra+, 2018)
J/ApJS/235/11 : Abs. features in SDSS. I. MgII abs. doublets (Chen+, 2018)
J/ApJS/242/28 : MgII-BAL quasar variability in SDSS spectra (Yi+, 2019)
J/ApJ/882/4 : SDSS-RM project: Ha, Hb & MgII lines (Wang+, 2019)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Quasars' name (JHHMMSS+DDMMSS)
16- 21 F6.1 rad/m2 RM [-153.2/117.3] Rotation measure,
Taylor+ (2009, J/ApJ/702/1230)
23- 26 F4.1 rad/m2 e_RM [0.1/29] Error in RM
28- 32 F5.1 rad/m2 GRM [-91.5/126] Galactic rotation measure,
Xu+ (2014, J/other/RAA/14.942)
34- 37 F4.1 rad/m2 e_GRM [0.5/14] Error in GRM
39- 44 F6.1 rad/m2 RRM [-119/102] Residual Rotation measure, RRM=RM-GRM
46- 49 F4.1 rad/m2 e_RRM [0.7/29] Error in RRM
51- 51 I1 --- NMgII [0/5] Number of MgII absorbers along the line of
sight of quasar
53- 58 F6.4 --- zem [0.38/2.3] Redshift of the quasar from
SDSS DR-7, 9, 12 and 14
60- 64 F5.2 % p [0.54/20.83] Fractional polarisation,
Taylor+ (2009, J/ApJ/702/1230)
66- 69 F4.2 % e_p [0/1.8] Error in p
71- 75 F5.2 --- alpha [-1.25/0.9]? Total intensity spectral index
α, Farnes+ (2014, J/ApJS/212/15)
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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 --- Name Quasars' name (JHHMMSS+DDMMSS)
16- 21 F6.4 --- zem [0.42/2.3] Emission redshift, quasar,
from SDSS DR-7, 9, 12 & 14
23- 27 F5.3 --- zabs [0.36/2.25] Absorption redshift,
intervening Mg II absorber
29- 32 F4.2 0.1nm EWMgII [0.14/5.2] Equivalent width of the MgII doublet
line at 2796Å in Angstrom units
34- 37 F4.2 0.1nm e_EWMgII [0.03/0.8] Uncertainty in EWMgII
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Aug-2021