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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
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:
FileName Lrecl Records Explanations
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"
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.
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
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 chi2 color: each pair's color similarity statistic (4) 100 A1 --- f_Dphi [*] Possible lens (5) 101-104 F4.2 arcsec Dphi Angular pair separation
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).
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 chi2 color: each pair's color similarity statistic (5) 97-100 F4.2 arcsec Dphi Angular pair separation
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), h = SDSS J1432-0106B was discovered by Hewett et al. (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), confirmed as a possible lens by Djorgovski & Spinrad (1984ApJ...282L...1D), and likely a binary instead; e.g., Kochanek et al. (1999ApJ...510..590K); Peng et al., 1999ApJ...524..572P; Rusin 2002ApJ...572..705R), i = part of the quad lens from Inada et al. (2003Natur.426..810I), o = Oguri et al. (2005ApJ...622..106O), I = Inada et al. (2008, Cat. J/AJ/135/496). Note (5): Following equation 1. See section 3.
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 <QSO JHHMM+DDMMA> in Simbad. History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 20-Sep-2010
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