J/ApJS/217/5 HAQ survey: red QSO candidates follow-up (Krogager+, 2015)
The High AV Quasar Survey: reddened quasi-stellar objects selected from
optical/near-infrared photometry. II.
Krogager J.-K., Geier S., Fynbo J.P.U., Venemans B.P., Ledoux C.,
Moller P., Noterdaeme P., Vestergaard M., Kangas T., Pursimo T.,
Saturni F.G., Smirnova O.
<Astrophys. J. Suppl. Ser., 217, 5 (2015)>
=2015ApJS..217....5K 2015ApJS..217....5K
ADC_Keywords: QSOs ; Redshifts ; Spectroscopy ; Extinction ;
Photometry, SDSS ; Surveys
Keywords: galaxies: active; quasars: absorption lines; quasars: general
Abstract:
Quasi-stellar objects (QSOs) whose spectral energy distributions
(SEDs) are reddened by dust either in their host galaxies or in
intervening absorber galaxies are to a large degree missed by optical
color selection criteria like the ones used by the Sloan Digital Sky
Survey (SDSS). To overcome this bias against red QSOs, we employ a
combined optical and near-infrared (near-IR) color selection. In this
paper, we present a spectroscopic follow-up campaign of a sample of
red candidate QSOs which were selected from the SDSS and the UKIRT
Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and
SDSS/UKIDSS photometry are supplemented by mid-infrared photometry
from the Wide-field Infrared Survey Explorer. In our sample of 159
candidates, 154 (97%) are confirmed to be QSOs. We use a statistical
algorithm to identify sightlines with plausible intervening absorption
systems and identify nine such cases assuming dust in the absorber
similar to Large Magellanic Cloud sightlines. We find absorption
systems toward 30 QSOs, 2 of which are consistent with the best-fit
absorber redshift from the statistical modeling. Furthermore, we
observe a broad range in SED properties of the QSOs as probed by the
rest-frame 2µm flux. We find QSOs with a strong excess as well as
QSOs with a large deficit at rest-frame 2µm relative to a QSO
template. Potential solutions to these discrepancies are discussed.
Overall, our study demonstrates the high efficiency of the
optical/near-IR selection of red QSOs.
Description:
During a range of observing runs in 2012, 2013, and 2014, 159
candidate red QSOs were observed with the Nordic Optical Telescope
(NOT) on La Palma, using the Andalucia Faint Object Spectrograph and
Camera (ALFOSC). As in Paper I (Fynbo et al. 2013ApJS..204....6F 2013ApJS..204....6F), we
used grism #4, which covers the wavelength range from about 3200 to
9100Å at a resolution of about 300 with a slit width of 1.3 arcsec.
See section 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 159 Full sample observed with the NOT
table2.dat 76 159 Results of the spectroscopic follow-up
table5.dat 101 32 Intervening absorption systems
tablef1.dat 44 355 Remaining candidate QSOs
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
VIII/90 : The FIRST Survey Catalog, Version 12Feb16 (Becker+ 2012)
VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004)
J/A+A/572/A12 : GRB 140506A spectra (Fynbo+, 2014)
J/AJ/145/157 : Reddening curve of IRAS 14026+4341 (Jiang+, 2013)
J/ApJ/757/51 : FIRST-2MASS dust-reddened QSO spectra (Glikman+, 2012)
J/ApJ/753/125 : NIR spectroscopy follow-up of 60 SDSS-DR7 QSOs (Shen+, 2012)
J/MNRAS/424/2876 : Large area KX quasar catalogue (Maddox+, 2012)
J/A+A/541/A77 : Kohonen-selected unusual SDSS quasars (Meusinger+, 2012)
J/ApJS/199/3 : The quasars MMT-BOSS pilot survey (Ross+, 2012)
J/AJ/141/105 : NIR-matched quasar catalog (Peth+, 2011)
J/A+A/505/1087 : DLAs in SDSS-DR7 (Noterdaeme+, 2009)
J/ApJ/698/1095 : The FIRST-2MASS red QSO survey. II. (Urrutia+, 2009)
J/MNRAS/386/1605 : Luminous K-band selected QSOs from UKIDSS (Maddox+, 2008)
J/A+A/478/701 : Color excess of SDSS quasars with DLA systems (Vladilo+, 2008)
J/ApJ/667/673 : FIRST-2MASS red quasar survey (Glikman+, 2007)
J/AJ/133/186 : Optical spectroscopy of luminous AGNs and QSOs (Lacy+, 2007)
J/ApJS/166/470 : SDSS-Spitzer type I QSOs IR photometry (Richards+, 2006)
J/ApJ/642/673 : IR-selected obscured AGN candidates (Polletta+, 2006)
J/ApJ/640/579 : Near-infrared spectra of 27 SDSS quasars (Glikman+, 2006)
J/AJ/121/2308 : Sloan Digital Sky Survey quasar photometry (Richards+, 2001)
http://www.sdss.org/ : SDSS home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [HAQ]
4- 12 A9 --- HAQ Target designation (HHMM+DDMM; J2000)
14- 15 I2 h RAh Hour of right ascension (J2000)
17- 18 I2 min RAm Minute of right ascension (J2000)
20- 25 F6.3 s RAs Second of right ascension (J2000)
27 A1 --- DE- Sign of declination (J2000)
28- 29 I2 deg DEd Degree of declination (J2000)
31- 32 I2 arcmin DEm Arcminute of declination (J2000)
34- 38 F5.2 arcsec DEs Arcsecond of declination (J2000)
40- 44 F5.2 mag rmag [16/20.2] SDSS r-band AB magnitude
46- 54 A9 --- Tel Telescope(s) (NOT and/or BOSS)
56- 67 A12 s Exp Exposure time(s)
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [HAQ]
4- 12 A9 --- HAQ Target designation (HHMM+DDMM; J2000)
14 A1 --- f_HAQ [b] Flag on HAQ (1)
16- 22 A7 --- Type Type of object (2)
24 A1 --- u_z [~] Uncertainty flag on z
25- 28 F4.2 --- z [0/3.8]? QSO redshift
30 A1 --- u_A(V) [~] Uncertainty flag on A(V)
31- 35 F5.2 mag A(V) [-0.05/1.3]? V-band extinction (3)
37 A1 --- f_A(V) [a] Flag on A(V) (1)
39 A1 --- l_Frad Limit flag on Frad
41- 46 F6.2 mJy Frad [0.2/882.6] FIRST 1.4GHz flux density
48- 51 F4.2 mJy e_Frad [0.08/0.3]? Frad uncertainty
53- 76 A24 --- Notes Notes
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Note (1): Flag as follows:
a = Systems with intervening dust. Here we give the estimated A(V) at the
absorber redshift assuming the LMC extinction curve.
b = The spectrum for this target does not correspond to the photometry in
SDSS, since a wrong target was accidentally put on the slit. The real
SDSS identifier for this spectrum is J225430.2+063833.8.
Note (2): In cases where SDSS legacy had flagged the object as QSO for
follow-up, this is indicated by "QSO_HIZ" or "QSO_CAP".
The classification of broad absorption line (BAL) QSOs does not
follow a stringent methodology. For a detailed study and
classification of BAL QSOs in our sample, we refer the reader to
Saturni et al. (2014AdSpR..54.1434S 2014AdSpR..54.1434S).
Note (3): We estimate the extinction of each QSO by fitting a QSO template to
the photometry and spectrum combined. See section 4.1.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [HAQ]
4- 12 A9 --- HAQ Target designation (HHMM+DDMM; J2000)
14- 17 F4.2 --- z [0.8/3.8] QSO redshift
19- 22 F4.2 --- zsp [0.2/3.3] Spectroscopic redshift of the
absorption system
23 A1 --- u_zsp Tentative detections due to low S/N
25- 28 F4.2 --- zabs [1.1/2.4]? The absorber redshift (1)
30- 33 F4.2 --- e_zabs [0.03/0.1]? zabs uncertainty
35- 38 F4.2 mag A(V)a [0.2/0.5]? V-band extinction at the absorber
redshift (1)
40- 43 F4.2 mag e_A(V)a [0.02/0.07]? A(V)a uncertainty
45- 49 F5.2 mag A(V)q [-0.05/0.8] V-band extinction at the QSO redshift
51- 54 F4.2 mag e_A(V)q [0.01/0.03]? A(V)q uncertainty
56-101 A46 --- Notes Notes
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Note (1): Redshift and extinction values are only given in cases where the
absorber model was preferred in the likelihood ratio test described
in Section 4.1.1. The values reported here assume LMC type dust at
the absorber redshift from the fit.
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Byte-by-byte Description of file: tablef1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [HAQ]
4- 12 A9 --- HAQ Target designation (HHMM+DDMM; J2000)
14- 15 I2 h RAh Hour of Right Ascension (J2000)
17- 18 I2 min RAm Minute of Right Ascension (J2000)
20- 25 F6.3 s RAs Second of Right Ascension (J2000)
27 A1 --- DE- Sign of the Declination (J2000)
28- 29 I2 deg DEd Degree of Declination (J2000)
31- 32 I2 arcmin DEm Arcminute of Declination (J2000)
34- 38 F5.2 arcsec DEs Arcsecond of Declination (J2000)
40- 44 F5.2 mag rmag [17.4/21.2] SDSS r-band AB magnitude
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History:
From electronic version of the journal
References:
Fynbo et al. Paper I. 2013ApJS..204....6F 2013ApJS..204....6F
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 15-Apr-2015