J/MNRAS/468/77 Sample of confirmed quasar pairs (Eftekharzadeh+, 2017)
Clustering on very small scales from a large sample of confirmed quasar pairs:
does quasar clustering track from Mpc to kpc scales?
Eftekharzadeh S., Myers A.D., Hennawi J.F., Djorgovski S.G., Richards G.T.,
Mahabal A.A., Graham M.J.
<Mon. Not. R. Astron. Soc., 468, 77-90 (2017)>
=2017MNRAS.468...77E 2017MNRAS.468...77E (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; QSOs
Keywords: surveys - quasars: general - cosmology: observations -
large-scale structure of universe
Abstract:
We present the most precise estimate to date of the clustering of
quasars on very small scales, based on a sample of 47 binary quasars
with magnitudes of g < 20.85 and proper transverse separations of
∼25h-1kpc. Our sample of binary quasars, which is about six times
larger than any previous spectroscopically confirmed sample on these
scales, is targeted using a kernel density estimation (KDE) technique
applied to Sloan Digital Sky Survey (SDSS) imaging over most of the
SDSS area. Our sample is 'complete' in that all of the KDE target
pairs with 17.0≤R≤36.2h-1kpc in our area of interest have been
spectroscopically confirmed from a combination of previous surveys and
our own long-slit observational campaign. We catalogue 230 candidate
quasar pairs with angular separations of <8 arcsec, from which our
binary quasars were identified. We determine the projected correlation
function of quasars (_ p_) in four bins of proper transverse scale
over the range 17.0≤R≤36.2h-1kpc. The implied small-scale quasar
clustering amplitude from the projected correlation function,
integrated across our entire redshift range, is A=24.1±3.6 at
∼26.6h-1kpc. Our sample is the first spectroscopically confirmed
sample of quasar pairs that is sufficiently large to study how quasar
clustering evolves with redshift at ∼25h-1kpc. We find that
empirical descriptions of how quasar clustering evolves with redshift
at ∼25h-1Mpc also adequately describe the evolution of quasar
clustering at ∼25h-1kpc.
Description:
We present by far the largest sample of spectroscopically confirmed
binary quasars with proper transverse separations of
17.0≤R≤36.2h-1kpc. Our sample, which is ∼6x larger than any
previous homogeneously selected sample on these proper scales, is
derived from SDSS imaging over an area corresponding to SDSS DR6. Our
quasars are targeted using a KDE technique, and confirmed using
long-slit spectroscopy on a range of facilities. We derive a
statistically complete subsample of 47 binary quasars with g<20.85,
which extends across angular scales of 2.9-arcsec
<{DELTA}θ<6.3-arcsec and redshifts of 0.43<z<2.26.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table5.dat 57 460 Candidate quasar pairs drawn from our
parent sample
table6.dat 119 47 Complete sample of 47 spectroscopically
confirmed binaries
table3.dat 21 184 Normalized distribution of the spectroscopic
redshifts for quasar candidates in our
parent sample
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See also:
VII/243 : SDSS quasar catalog. III. (Schneider+, 2005)
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
J/ApJ/651/61 : Optically thick absorbers near luminous quasars (Hennawi+ 2006)
J/AJ/135/496 : SDSS quasar lens search. II. (Inada+, 2008)
J/ApJ/678/635 : Spectroscopy of quasar binary candidates (Myers+, 2008)
J/ApJ/776/136 : QPQ VI. HI absorption of z∼2 quasars (Prochaska+, 2013)
J/ApJ/796/140 : Circumgalactic medium surrounding z∼2 quasars (Prochaska+ 2014)
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.3 arcsec Dtheta Angular separation of the two members of
the pair, {DELTA}θ
7 I1 --- ObsStat [0/2]? Observational status of the pair (1)
9- 17 F9.5 deg RAdeg Right ascension (J2000)
19- 27 F9.5 deg DEdeg Declination (J2000)
29- 33 F5.2 mag imag Dereddened i magnitude
35- 39 F5.2 mag gmag Dereddened g magnitude
41- 46 A6 --- Class Spectroscopic classification (2)
48- 53 F6.3 --- zsp ?=-1 Measured or reported spectroscopic
redshift for the members,
-1 for objects with no redshift
55 I1 --- QQ? [1/4]? Classification of the pair (3)
57 A1 --- Note [*] Note (4)
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Note (1): Observational status of the pair as follows:
0 = there is insufficient information to determine the redshift of a candidate
1 = sources confirmed by this study
2 = sources confirmed in previous studies
(Schneider et al. 2005AJ....130..367S 2005AJ....130..367S, Cat. VII/243;
Hennawi et al. 2006, J/ApJ/651/61; Inada et al. 2008, Cat. J/AJ/135/496;
Myers et al. 2008, Cat. J/ApJ/678/635; Oguri et al., 2008AJ....135..512O 2008AJ....135..512O;
Schneider et al. 2010AJ....139.2360S 2010AJ....139.2360S, Cat. VII/260;
Oguri et al. 2012AJ....143..120O 2012AJ....143..120O;
Prochaska et al. 2013, Cat. J/ApJ/776/136;
Prochaska, Lau Hennawi 2014, Cat. J/ApJ/796/140;
Paris et al. 2017A&A...597A..79P 2017A&A...597A..79P, Cat. VII/279)
Note (2): Spectroscopic classification as follows:
Q = Quasar
G = Galaxy
S = Star
U = No Spectrum
NQ = A spectrum exists but it did not yield a definitive classification
(i.e "Not a quasar")
Note (3): Classification of the pair as follows:
1 = lacking sufficient spectroscopic information to define its nature
2 = a projected pair (star-star, star-quasar, two quasars at different
redshifts etc.)
3 = a binary quasar
4 = a gravitational lens
Note (4): * = we removed this pair from our "relevant pair" sample that
consisted of two high signal-to-noise but featureless ("continuum") sources.
Even if this pair is a binary quasar, we would have no way to assign it a
redshift.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- NameA Name of the brighter quasar of the binary,
SDSS JHHMM+DDMM A (1)
19- 27 F9.5 deg RAAdeg Right ascension (J2000) of brighter quasar
29- 36 F8.5 deg DEAdeg Declination (J2000) of brighter quasar
38- 42 F5.2 mag imagA Dereddened i magnitude of brighter quasar
44- 48 F5.2 mag gmagA Dereddened g magnitude of brighter quasar
50- 66 A17 --- NameB Name of the fainter quasar of the binary,
SDSS JHHMM+DDMM B (1)
68- 76 F9.5 deg RABdeg Right ascension (J2000) of fainter quasar
78- 85 F8.5 deg DEBdeg Declination (J2000) of fainter quasar
87- 91 F5.2 mag imagB Dereddened i magnitude of fainter quasar
93- 97 F5.2 mag gmagB Dereddened g magnitude of fainter quasar
99-103 F5.3 arcsec Dtheta Angular separation of the quasars
in the binary
105-109 F5.3 --- zsp Spectroscopic redshift for the binary
111-114 I4 km/s |DV| Velocity difference between the quasars in
the binary
116-119 F4.1 kpc R Transverse proper separation between the
quasars in the binary, in h-1kpc unit
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Note (1): name of the members of the binary, where the brighter and fainter
quasars in the pair in g band are referred to as 'A' or 'B', respectively;
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 F5.3 --- zmin Lower value of Δz interval (1)
6 A1 --- --- [-]
7- 11 F5.3 --- zmax Upper value of Δz interval (1)
14- 21 F8.6 --- (1/N)dN/dz Normalized distribution
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Note (1): The covered redshift range is 0.4<z<2.3 with the dz=0.01.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 21-Mar-2020