J/ApJ/678/635 Spectroscopy of quasar binary candidates (Myers+, 2008)
Quasar clustering at 25 h-1 kpc from a complete sample of binaries.
Myers A.D., Richards G.T., Brunner R.J., Schneider D.P., Strand N.E.,
Hall P.B., Blomquist J.A., York D.G.
<Astrophys. J., 678, 635-646 (2008)>
=2008ApJ...678..635M 2008ApJ...678..635M
ADC_Keywords: Binaries, spectroscopic ; Redshifts ; QSOs
Keywords: cosmology: observations - large-scale structure of universe -
quasars: general - surveys
Abstract:
We present spectroscopy of binary quasar candidates, with component
separations of 3"≤Δθ<6", selected from SDSS DR4 using
kernel density estimation (KDE). Of our 27 new quasar pair
observations, 10 are binary quasars, which doubles the number of known
g<21 binaries with 3"≤Δθ<6" separations. Several of our
observed binaries are wide-separation lens candidates that merit
additional higher resolution spectroscopy, as well as deep imaging to
search for lensing galaxies. Our candidates are initially selected by
UV excess (u-g<1), but are otherwise selected irrespective of the
relative colors of the quasar pair, and we thus use them to suggest
optimal color similarity and photometric redshift approaches for
targeting binary quasars or projected quasar pairs. We find that a
third or more of all binary quasars have quite dissimilar components
on the basis of a typical color similarity criterion
(χ2color≲20). From a sample that is complete on proper scales
of 23.7h-1kpc<Rprop<29.9h-1kpc, we determine the projected
quasar correlation function.
Description:
Spectroscopy of our DR4 KDE binary quasar candidates was obtained with
the Ritchey-Chretien Spectrograph on the Mayall 4m telescope at Kitt
Peak National Observatory (KPNO) over five nights (UT 2007 February
22-26). We used a 1.5"x98" long slit set at the position angle of the
candidate binary, which allowed both components to be simultaneously
observed.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 10 DR4 KDE candidate binaries for which we have
observed one member
table2.dat 104 16 *Confirmed binary quasars in the DR4 KDE
candidate sample
table3.dat 104 20 Confirmed projected pairs in the DR4 KDE
candidate sample
table4.dat 104 8 *Ambiguous pairs in the DR4 KDE binary quasar
candidate sample
table5.dat 100 46 Previously identified DR4 KDE binary quasar
candidates with 3"≤Δθ<6"
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Note on table2.dat: We define a binary quasar by a line-of-sight velocity
difference of |Δv//|<2000km/s in the rest frame of either
component. The pair containing SDSS J143002.66+071415.6 has a velocity
difference of |Δv//|=2000±400km/s, which is just inside our
definition of a binary. Components are denoted A and B such that the
position angle from A to B lies between 0° and 180°.
Note on table4.dat: The ambiguities, and why we conclude that SDSS
J1235+6836 and SDSS J1507+2903 are binaries but the other pairs are
not, are discussed in Section 2.2.2.
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See also:
VII/260 : The SDSS-DR7 quasar catalog (Schneider+, 2010)
VII/258 : Quasars and Active Galactic Nuclei (13th Ed.) (Veron+ 2010)
J/AJ/135/496 : SDSS quasar lens search. II. (Inada+, 2008)
J/ApJS/175/29 : Spectroscopy of QSO pairs (Marble+, 2008)
J/ApJ/658/99 : Pairs of QSO in SDSS-DR4 (Myers+, 2007)
J/AJ/131/1 : Binary quasars in the SDSS (Hennawi+, 2006)
J/MNRAS/311/456 : RIXOS source catalogue (Mason+, 2000)
Byte-by-byte Description of file: table1.dat table2.dat table3.dat table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 4 A4 --- --- [SDSS]
6- 24 A19 --- SDSS SDSS designation (JHHMMSS.ss+DDMMSS.s or
JHHMM+DDMMA)
26- 27 I2 h RAh Hour of right ascension (J2000)
29- 30 I2 min RAm Minute of right ascension (J2000)
32- 37 F6.3 s RAs Second of right ascension (J2000)
39 A1 --- DE- Declination sign (J2000)
40- 41 I2 deg DEd Degree of declination (J2000)
43- 44 I2 arcmin DEm Arcminute of declination (J2000)
46- 50 F5.2 arcsec DEs Arcsecond of declination (J2000)
52- 56 F5.2 mag gmag g-band magnitude not corrected for Galactic
extinction
58- 61 F4.2 --- zlow Lowest extent of photometric redshift range
63- 67 F5.3 --- zpeak Peak of photometric redshift range
69- 72 F4.2 --- zhigh Highest extent of photometric redshift range
74- 78 F5.3 --- pr(z) probability of the true redshift lying in
this range
79- 83 F5.3 --- zSDSS ?=- SDSS spectroscopic redshift (1)
85 A1 --- n_z [*NFPO] Note on z (2)
86- 90 F5.3 --- z ?=- Spectroscopic redshift from KPNO data (1)
91 A1 --- u_z [D?] when redshift is based on a single
emission line (3)
93- 98 F6.1 --- chi2 χ2 color: each pair's color similarity
statistic (4)
100 A1 --- f_Dphi [*] Possible lens (5)
101-104 F4.2 arcsec Dphi Angular pair separation
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Note (1): The zSDSS column shows matches to any spectroscopic object in the
SDSS DR6 Catalog Archive Server (mainly, e.g., Schneider et al. 2007,
Cat. VII/252 obsoleted by VII/260). In the zSDSS and "Our z" columns
(z), the object is a quasar at the provided redshift, unless otherwise
noted.
Note (2): Flag as follows:
P = SDSS J1320+3056A first appeared with a confirmed redshift (z=1.587) in
Veron-Cetty et al. (2004, Cat. VII/235 obsoleted by VII/258).
N = SDSS J112556.32+143148.0 is a NELG (narrow emission line galaxy).
O = Subsequent to our observations, SDSS J094309.36+103401.3 appeared in
Inada et al. (2008, Cat. J/AJ/135/496) with z=1.433.
F = Featureless
* = star
Note (3): which is reasonably assumed to be MgII except for
* SDSS J123122.37+493430.7 which is based on a single CIV emission line,
with weak confirming CIII].
* D = derived from a single emission line. This differs from the single
question mark notation, as the redshift is based on similar emission
in the other component (rather than simply assuming that the emission
is MgII).
Note (4): Following equation 1. See section 3.
Note (5): An asterisk denotes that our spectroscopy alone is insufficient
to rule out a lens interpretation for this pair (see Section 2.2.1).
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- oc Object categories (1)
4- 7 A4 --- --- [SDSS]
9- 27 A19 --- SDSS SDSS designation (JHHMMSS.ss+DDMMSS.s or
JHHMM+DDMMA) (2)
29- 30 I2 h RAh Hour of right ascension (J2000)
32- 33 I2 min RAm Minute of right ascension (J2000)
35- 40 F6.3 s RAs Second of right ascension (J2000)
42 A1 --- DE- Declination sign (J2000)
43- 44 I2 deg DEd Degree of declination (J2000)
46- 47 I2 arcmin DEm Arcminute of declination (J2000)
49- 53 F5.2 arcsec DEs Arcsecond of declination (J2000)
55- 59 F5.2 mag gmag g-band magnitude
61- 64 F4.2 --- zlow Lowest extent of photometric redshift range
66- 70 F5.3 --- zpeak Peak of photometric redshift range
72- 75 F4.2 --- zhigh Highest extent of photometric redshift range
77- 81 F5.3 --- pr(z) probability of the true redshift lying in this
range
83 A1 --- Rem [*mchf] Remark on object (3)
84- 88 F5.3 --- z ? Redshift from litterature
89 A1 --- f_z [SIDio] Flag on redshifts (4)
91- 95 F5.1 --- chi2 χ2 color: each pair's color similarity
statistic (5)
97-100 F4.2 arcsec Dphi Angular pair separation
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Note (1): Categories as follows:
PP = Projected pairs
BQ = Binary quasars
CL = Confirmed lenses
Note (2): Components of a binary are denoted A and B such that the position
angle from A to B lies between 0° and 180°. This convention
differs from Hennawi et al. (2006, Cat. J/AJ/131/1), from which we
take identifications and redshifts, except for objects flagged in
col. f_z.
Note (3): Flag as follows:
* = star
m = Both of the quasars SDSS J162902.59+372430.8 and
SDSS J162902.63+372435.1 first appear in Mason et al. (2000,
Cat. J/MNRAS/311/456).
c = SDSS J1004+4112A was discovered by Cao et al. (1999A&AS..135..243C 1999A&AS..135..243C),
h = SDSS J1432-0106B was discovered by Hewett et al. (1991AJ....101.1121H 1991AJ....101.1121H).
f = We note that we mistakenly listed SDSS J095454.73+373419.7 as lying at
z=1.554 in Myers et al. (2007, Cat. J/ApJ/658/99).
Note (4): Redshifts from Hennawi et al. (2006, Cat. J/AJ/131/1), except for
objects flagged as follows:
S = taken from the SDSS,
D = discovered by Sramek & Weedman (1978ApJ...221..468S 1978ApJ...221..468S), confirmed as a
possible lens by Djorgovski & Spinrad (1984ApJ...282L...1D 1984ApJ...282L...1D), and likely
a binary instead; e.g., Kochanek et al. (1999ApJ...510..590K 1999ApJ...510..590K); Peng et
al., 1999ApJ...524..572P 1999ApJ...524..572P; Rusin 2002ApJ...572..705R 2002ApJ...572..705R),
i = part of the quad lens from Inada et al. (2003Natur.426..810I 2003Natur.426..810I),
o = Oguri et al. (2005ApJ...622..106O 2005ApJ...622..106O),
I = Inada et al. (2008, Cat. J/AJ/135/496).
Note (5): Following equation 1. See section 3.
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Nomenclature note:
In table2 and 4, format JHHMM+DDMMA is <[MRB2008] JHHMM+DDMMA> in Simbad.
In table5, format JHHMM+DDMMA is <[HSO2006] JHHMM+DDMMA> or
in Simbad.
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 20-Sep-2010