J/A+A/660/A16 Quasars with large proper motions (Souchay+, 2022)
Quasars with large proper motions : A selection from the LQAC-5 catalogue
combined with Gaia EDR3. Focusing on astrometric and photometric properties.
Souchay J., Secrest N., Lambert S., Zacharias N., Taris F., Barache C.,
Arias F., Makarov V.
<Astron. Astrophys. 660, A16 (2022)>
=2022A&A...660A..16S 2022A&A...660A..16S (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Proper motions ; Optical
Keywords: astrometry - catalogs - proper motions - reference systems
Abstract:
Thanks to the cross-identification between the Gaia EDR3 (E-Data
Release 3) catalogue and the quasars' compiled catalogue LQAC-5
(Large Quasar Astrometric Catalogue-5), accurate astrometric
parameters as well as photometric measurements were available for a
set of 416113 quasars.
After analysing the astrometric and photometric properties of these
quasars,we concentrate our study on objects characterized
by significant proper motion, which contradicts the postulate that
they are fixed in the celestial sphere.
We derived statistical properties of the positions, parallaxes, and
proper motions of the quasars cross-matched with Gaia EDR3. We carried
out a specific investigation of quasars with a proper motion larger
than 10mas/y, and used colour-colour diagrams in mid-infrared to
discriminate these quasars from stellar contamination. We discuss, in
detail, a few cases where the abnormal proper motion could be caused
by misidentifications.
We note that 43% of LQAC-5 quasars were not detected by Gaia EDR3,
mainly because of the cut-off magnitude at G=21. The comparison
between r(G) (Gaia) and r (SDSS) shows a normal distribution. The
normalized distributions of parallaxes and proper motions are
identical to that of the Gaia CRF2, as well as the distribution of the
GBP-GRP colour index. We have identified 937 LQAC-5 objects (0.27% of
the sample) with Gaia EDR3 proper motion which is significant at the
5σ level. We have clearly shown that below z=0.35, the
integrated magnitude G(r) obtained from SDSS spectra is smaller than G
(Gaia), leading to the statement that the quasars are generally
resolved under this threshold, which should lead to a bad
determination of proper motion. Moreover, to discriminate quasars from
stellar contamination, we have plotted them in a mid-infrared
colour-colour diagram. Finally, we have made a final selection of 41
objects with µ>10mas/y, satisfying drastic constraints, which makes
them potential candidates for considering their proper motion as real.
In this paper we carried out a complete analysis of the quasars of the
LQAC-5 which were cross-identified with Gaia EDR3 ; this serves as an
alternative and complementary study with respect to Gaia CRF2,
involving a different population of quasars. We selected a set of 41
quasars with a proper motion exceeding 10 mas/y, which can be
considered as very high for objects which are a priori fixed in the
celestial sphere.
Description:
We have constructed an improved version of the LQAC5 catalogue
(Souchay et al., 2019A&A...624A.145S 2019A&A...624A.145S, Cat. J/A+A/624/A145), which we
called LQAC5+, by matching its total sample of 592809 quasars with the
Gaia EDR3 catalogue (Gaia Collabaration, 2020, Cat. I/350).
We present a sample of the 41 LQAC-5 quasars selected from Gaia EDR3
data with µ>10 mas/yr, χµ>5, π/σπ<4 and
located in the quasars central zone .
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 105 41 Sample of the 41 LQAC-5 quasars selected from
Gaia EDR3 data with µ>10mas/yr,
χµ>5, π/σπ<4 and located
in the quasars central zone
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/A+A/624/A145 : Astrometric Catalogue 5, LQAC-5 (Souchay+, 2019)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Ref Reference for cross-identification (1)
3- 16 F14.10 deg RAdeg Gaia EDR3 right ascension (ICRS) at Ep=2016.0
18- 22 F5.3 mas e_RAdeg Rigth ascension error
24- 37 F14.10 deg DEdeg Gaia EDR3 declination (ICRS) at Ep=2016.0
39- 43 F5.3 mas e_DEdeg Declination error
45- 49 F5.3 --- z ?=- Redshift
51- 56 F6.3 mas plx Parallax
58- 62 F5.3 mas e_plx Parallax error
64- 69 F6.3 mas/yr pm Total proper motion
71- 75 F5.3 mas/yr e_pm Total proper motion error
77- 80 I4 --- N Number of observations in Gaia EDR3
82- 86 F5.2 mag Gmag Gaia G magnitude
88- 94 F7.3 --- P1 Gaia EDR3 ASTROMETRIC-GOF-AL parameter
96-101 F6.3 mas P2 Gaia EDR3 ASTROMETRIC-EXCESS-NOISE parameter
103-105 I3 mas double ? Angular distance between the 6 detected
Gaia EDR3 binary components
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Note (1): symbols for the cross-identifications as follows:
A = Hewitt and Burbridge (1993ApJS...87..451H 1993ApJS...87..451H, cat. VII/158)
B = SDSS (Paris et al., 2017A&A...597A..79P 2017A&A...597A..79P, Cat. VII/279)
C = Veron and Veron-Cetty (2010A&A...518A..10V 2010A&A...518A..10V, Cat. VII/258)
D = 2QZ (Croom et al., 2004MNRAS.349.1397C 2004MNRAS.349.1397C, Cat. VII/241)
E = VLBA
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Mar-2022