J/ApJ/756/28 IR counterparts to submm H-ATLAS galaxies (Kim+, 2012)
SPITZER-IRAC identification of HERSCHEL-ATLAS SPIRE sources.
Kim S., Wardlow J.L., Cooray A., Fleuren S., Sutherland W., Khostovan A.A.,
Auld R., Baes M., Bussmann R.S., Buttiglione S., Cava A., Clements D.,
Dariush A., De Zotti G., Dunne L., Dye S., Eales S., Fritz J., Hopwood R.,
Ibar E., Ivison R., Jarvis M., Maddox S., Michalowski M.J., Pascale E.,
Pohlen M., Rigby E., Scott D., Smith D.J.B., Temi P., van der Werf P.
<Astrophys. J., 756, 28 (2012)>
=2012ApJ...756...28K 2012ApJ...756...28K
ADC_Keywords: Galaxies, IR ; Photometry, infrared ; Millimetric/submm sources ;
Redshifts
Keywords: galaxies: high-redshift; galaxies: starburst; infrared: galaxies
Abstract:
We use Spitzer-IRAC data to identify near-infrared counterparts to
submillimeter galaxies detected with Herschel-SPIRE at 250µm in the
Herschel Astrophysical Terahertz Large Area Survey. Using a likelihood
ratio analysis we identify 146 reliable IRAC counterparts to 123 SPIRE
sources out of the 159 in the survey area. We find that, compared to
the field population, the SPIRE counterparts occupy a distinct region
of the 3.6 and 4.5µm color-magnitude space, and we use this
property to identify 23 further counterparts to 13 SPIRE sources. The
IRAC identification rate of 86% is significantly higher than those
that have been demonstrated with wide-field ground-based optical and
near-IR imaging of Herschel fields. We estimate a false identification
rate of 3.6%, corresponding to 4-5 sources. Among the 73 counterparts
that are undetected in Sloan Digital Sky Survey, 57 have both 3.6 and
4.5µm coverage. Of these, 43 have [3.6]-[4.5]>0, indicating that
they are likely to be at z≳1.4. Thus, ∼40% of identified SPIRE
galaxies are likely to be high-redshift (z≳1.4) sources. We discuss
the statistical properties of the IRAC-identified SPIRE galaxy sample
including far-IR luminosities, dust temperatures, star formation
rates, and stellar masses. The majority of our detected galaxies have
1010-1011L☉ total IR luminosities and are not intense
starbursting galaxies as those found at z∼2, but they have a factor of
2-3 above average specific star formation rates compared to near-IR
selected galaxy samples.
Description:
The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS; Eales
et al. 2010PASP..122..499E 2010PASP..122..499E) is the largest open-time key project being
undertaken by the Herschel Space Observatory. The total planned survey
area is 550deg2 within which it is expected to detect >300000 bright
sub-mm galaxies. During the Science Demonstration Phase (SDP), H-ATLAS
observed 14.4deg2 in the Galaxy And Mass Assembly (GAMA; Driver et
al. 2011, Cat. J/MNRAS/413/971) 9hr field, to 5σ depths of
35-132mJy in five bands from 100 to 500um, using PACS (100 and 160um)
and SPIRE (250, 350, and 500um) in parallel mode. The SDP field has
existing SDSS, VIKING, and UKIDSS data. The H-ATLAS PACS and SPIRE
map-making processes are described in Ibar et al.
(2010MNRAS.409...38I 2010MNRAS.409...38I) and Pascale et al. (2011MNRAS.415..911P 2011MNRAS.415..911P),
respectively, and details of the source extraction procedures are
given in Rigby et al. (2011, Cat. J/MNRAS/415/2336).
Spitzer-IRAC 3.6 and 4.5um staring mode observations of 0.4deg2, in
three regions of the H-ATLAS SDP field, were carried out during the
warm mission (Spitzer program 548; PI: A. Cooray). Two of the areas
targeted contain bright SPIRE SDP sources that are now known to be
gravitationally lensed (ID81 and ID130; Negrello et al.
2010Sci...330..800N 2010Sci...330..800N; Hopwood et al. 2011ApJ...728L...4H 2011ApJ...728L...4H) and the third
area was chosen as a test field.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 201 146 Combined photometry for IRAC identifications
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See also:
II/329 : VIKING catalogue data release 1 (Edge+, 2013)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
VII/252 : SDSS-DR5 quasar catalog (Schneider+, 2007)
J/ApJ/749/65 : Strongly lensed galaxies in H-ATLAS (Gonzalez-Nuevo+, 2012)
J/MNRAS/421/3027 : Statisical study of galaxy dust emissions (Bourne+, 2012)
J/AJ/143/125 : SED of 113 dust-obscured galaxies at z∼2 (Melbourne+, 2012)
J/MNRAS/415/2336 : Herschel-ATLAS Science Demonstration Catalog (Rigby+, 2011)
J/MNRAS/413/2314 : Radio and MIR counterpart of submm galaxies (Biggs+, 2011)
J/MNRAS/413/971 : Galaxy And Mass Assembly (GAMA) DR1 (Driver+, 2011)
J/ApJ/699/1610 : Spitzer survey of submillimeter galaxies (Hainline+, 2009)
http://www.h-atlas.org/ : H-ATLAS web site
http://www.sdss.org/ : SDSS home page
http://www.eso.org/sci/observing/phase3/data_releases.html : ESO VISTA
releases (including VIKING)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- HATLAS IAU name (JHHMMSS.s+DDMMSS;
<H-ATLAS JHHMMSS.s+DDMMSS> in Simbad)
18- 22 I5 --- SDP [81/15947] H-ATLAS identification number
24 A1 --- f_SDP [s] s: ID with color-magnitude method (1)
26- 27 I2 h RAh IRAC hour of right ascension (J2000)
29- 30 I2 min RAm IRAC minute of right ascension (J2000)
32- 36 F5.2 s RAs IRAC second of right ascension (J2000)
38 A1 --- DE- IRAC sign of declination (J2000)
39- 40 I2 deg DEd IRAC degree of declination (J2000)
42- 43 I2 arcmin DEm IRAC arcminute of declination (J2000)
45- 48 F4.1 arcsec DEs IRAC arcsecond of declination (J2000)
50 A1 --- l_Zmag Limit flag on Zmag
52- 56 F5.2 mag Zmag [16.7/23.1]? VIKING Z-band magnitude (2)
58- 62 F5.2 mag e_Zmag [16.7/22.8]? Zmag uncertainty (2)(5)
64 A1 --- l_Ymag Limit flag on Ymag
66- 70 F5.2 mag Ymag [16.7/22.7]? VIKING Y-band magnitude (2)
72- 75 F4.2 mag e_Ymag [0/0.3]? Ymag uncertainty (2)
77 A1 --- l_Jmag Limit flag on Jmag
79- 83 F5.2 mag Jmag [16.5/22.2]? VIKING J-band magnitude (2)
85- 88 F4.2 mag e_Jmag [0/0.3]? Jmag uncertainty (2)
90 A1 --- l_Hmag Limit flag on Hmag
92- 96 F5.2 mag Hmag [16.2/21.3]? VIKING H-band magnitude (2)
98-101 F4.2 mag e_Hmag [0/0.3]? Hmag uncertainty (2)
103 A1 --- l_Ksmag Limit flag on Ksmag
105-109 F5.2 mag Ksmag [16.3/21]? VIKING Ks-band magnitude (2)
111-114 F4.2 mag e_Ksmag [0/0.2]? Ksmag uncertainty (2)
116 A1 --- l_[3.6] Limit flag on [3.6]
118-122 F5.2 mag [3.6] [16.5/23]? Spitzer/IRAC 3.6um band magnitude
124-127 F4.2 mag e_[3.6] [0.01/0.1]? [3.6] uncertainty
129-133 F5.2 mag [4.5] [16.3/20.9]? Spitzer/IRAC 4.5um band magnitude
135-138 F4.2 mag e_[4.5] [0.01/0.1]? [4.5] uncertainty
140-145 F6.2 mJy S250 [22.5/129] Herschel/SPIRE 250um flux
147-150 F4.2 mJy e_S250 [6.2/8] S250 uncertainty
152-157 F6.2 mJy S350 [6.5/181.9] Herschel/SPIRE 350um flux (3)
159-162 F4.2 mJy e_S350 [7.1/7.4] S350 uncertainty (3)
164-169 F6.2 mJy S500 [-12.4/166] Herschel/SPIRE 500um flux (3)
171-174 F4.2 mJy e_S500 [8.7/9.4] S500 uncertainty (3)
176-180 F5.3 --- R3.6 [0/1]? Reliability of the counterparts
at 3.6um (4)
182-186 F5.3 --- R4.5 [0/1]? Reliability of the counterparts
at 4.5um (4)
188-191 F4.2 --- z [0.05/0.8]? SDSS-DR7 redshift for sources
detected in that survey
193-196 F4.2 --- e_z [0/0.3]? z uncertainty
198-201 F4.2 arcsec Sep [0.4/7] Separation between the centroid of the
SPIRE emission and the IRAC counterpart
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Note (1): 23 IRAC counterparts were determined by the color-magnitude method
instead of the Likelihood Ratio (LR) method. See section 3.4.
Note (2): Photometry from the VIKING (VISTA Kilo-degree Infrared Galaxy Survey)
survey (Z, Y, J, H, Ks) is extracted in 2" diameter apertures
(W. Sutherland et al., 2012sngi.confE..40S).
Note (3): The reported SPIRE 350 and 500um fluxes are measured at the positions
of 250um sources; no S/N cut is applied.
Note (4): R is reliability of the counterparts calculated separately at 3.6 and
4.5um from the Likelihood Ratio (LR) method. To accept a potential
counterpart as reliable we require that R≥0.8, i.e., there is <20%
chance of a false association.
The LR, L is the ratio of the probability that the IRAC source is the
correct SPIRE counterpart with the equivalent probability for an
unassociated background source. Following Sutherland & Saunders
(1992MNRAS.259..413S 1992MNRAS.259..413S), L is calculated as L=(q(m)f(r))/n(m) where q(m)
and n(m) are the normalized magnitude distributions of counterparts
and background sources, respectively. The radial probability
distribution of the separation between the SPIRE 250um and IRAC
positions is denoted by f(r). (See section 3.1).
Note (5): This column is identical to the Zmag value; it will not be displayed
in the VizieR database (Note added by CDS).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 18-Mar-2014