J/ApJ/761/22 NIR galaxy cluster candidates in the SPT survey (Song+, 2012)
Redshifts, sample purity, and BCG positions for the galaxy cluster catalog from
the first 720 square degrees of the South Pole Telescope survey.
Song J., Zenteno A., Stalder B., Desai S., Bleem L.E., Aird K.A.,
Armstrong R., Ashby M.L.N., Bayliss M., Bazin G., Benson B.A., Bertin E.,
Brodwin M., Carlstrom J.E., Chang C.L., Cho H.M., Clocchiatti A.,
Crawford T.M., Crites A.T., de Haan T., Dobbs M.A., Dudley J.P.,
Foley R.J., George E.M., Gettings D., Gladders M.D., Gonzalez A.H.,
Halverson N.W., Harrington N.L., High F.W., Holder G.P., Holzapfel W.L.,
Hoover S., Hrubes J.D., Joy M., Keisler R., Knox L., Lee A.T., Leitch E.M.,
Liu J., Lueker M., Luong-Van D., Marrone D.P., McDonald M., McMahon J.J.,
Mehl J., Meyer S.S., Mocanu L., Mohr J.J., Montroy T.E., Natoli T.,
Nurgaliev D., Padin S., Plagge T., Pryke C., Reichardt C.L., Rest A.,
Ruel J., Ruhl J.E., Saliwanchik B.R., Saro A., Sayre J.T., Schaffer K.K.,
Shaw L., Shirokoff E., Suhada R., Spieler H.G., Stanford S.A.,
Staniszewski Z., Stark A.A., Story K., Stubbs C.W., van Engelen A.,
Vanderlinde K., Vieira J.D., Williamson R., Zahn O.
<Astrophys. J., 761, 22 (2012)>
=2012ApJ...761...22S 2012ApJ...761...22S
ADC_Keywords: Clusters, galaxy ; Surveys ; Redshifts ; Photometry ;
Galaxies, IR
Keywords: cosmology: observations; galaxies: clusters: general;
galaxies: distances and redshifts
Abstract:
We present the results of the ground- and space-based optical and
near-infrared (NIR) follow-up of 224 galaxy cluster candidates
detected with the Sunyaev-Zel'dovich (SZ) effect in the 720deg2 of
the South Pole Telescope (SPT) survey completed in the 2008 and 2009
observing seasons. We use the optical/NIR data to establish whether
each candidate is associated with an overdensity of galaxies and to
estimate the cluster redshift. Most photometric redshifts are derived
through a combination of three different cluster redshift estimators
using red-sequence galaxies, resulting in an accuracy of
Δz/(1+z)=0.017, determined through comparison with a subsample
of 57 clusters for which we have spectroscopic redshifts. We
successfully measure redshifts for 158 systems and present redshift
lower limits for the remaining candidates. The redshift distribution
of the confirmed clusters extends to z=1.35 with a median of
zmed=0.57. Approximately 18% of the sample with measured redshifts
lies at z>0.8. We estimate a lower limit to the purity of this SPT
SZ-selected sample by assuming that all unconfirmed clusters are noise
fluctuations in the SPT data. We show that the cumulative purity at
detection significance ξ>5 (ξ>4.5) is ≥95% (≥70%). We present
the red brightest cluster galaxy (rBCG) positions for the sample and
examine the offsets between the SPT candidate position and the rBCG.
The radial distribution of offsets is similar to that seen in
X-ray-selected cluster samples, providing no evidence that SZ-selected
cluster samples include a different fraction of recent mergers from
X-ray-selected cluster samples.
Description:
In 2011 November, the South Pole Telescope (SPT) collaboration
completed a 2500deg2 survey, primarily aimed at detecting distant,
massive galaxy clusters through their Sunyaev-Zel'dovich (SZ) effect
signature. In Reichardt et al. (R12, 2013, Cat. J/ApJ/763/127), the
SPT team presented a catalog of 224 cluster candidates from 720deg2
observed in the 2008-2009 seasons with the 95GHz and 150GHz detectors.
In this work, we present the optical and near-infrared (NIR) follow-up
observations of the cluster candidates reported in R12 (see Table 2).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 40 61 Spectroscopic follow-up
table3.dat 101 224 All candidates above ξ=4.5 in 720deg2 of
the SPT-SZ survey (South Pole Telescope)
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See also:
VIII/88 : Planck Early Release Compact Source Catalogue (Planck, 2011)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/ApJS/209/22 : SSDF survey: IRAC catalogs (Ashby+, 2013)
J/ApJ/763/127 : Galaxy clusters discovered in the SPT survey (Reichardt+, 2013)
J/ApJ/757/83 : The Blanco Cosmology Survey (BCS) (Desai+, 2012)
J/ApJ/742/48 : Blanco survey of the lens BCS J2352-5452 (Buckley-Geer+, 2011)
J/ApJ/719/763 : Millimeter-wave sources in the SPT survey (Vieira+, 2010)
J/ApJ/716/530 : Mid-IR variability from the SDWFS (Kozlowski+, 2010)
J/MNRAS/403/2063 : SXDF X-ray groups and galaxy clusters (Finoguenov+, 2010)
J/A+A/499/357 : REFLEX galaxies redshifts (Guzzo+, 2009)
J/ApJ/686/966 : Spitzer-FLS catalog of clusters of galaxies (Muzzin+, 2008)
J/ApJ/684/905 : Galaxy clusters from IRAC Shallow Survey (Eisenhardt+, 2008)
J/ApJ/660/239 : MaxBCG cat. of galaxy clusters from SDSS (Koester+, 2007)
J/AJ/134/2398 : Stellar SEDs in SDSS and 2MASS filters (Covey+, 2007)
J/ApJS/172/182 : XMM Clusters of galaxies in COSMOS field (Finoguenov+ 2007)
J/ApJS/157/1 : Red-Sequence Cluster Survey (Gladders+, 2005)
J/A+A/425/367 : REFLEX Galaxy Cluster Survey catalogue (Boehringer+, 2004)
J/ApJ/502/558 : Catalog of ROSAT galaxy clusters (Vikhlinin+ 1998)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- --- [SPT-CL]
7- 16 A10 --- SPT-CL SPT identification (JHHMM+DDMM)
18- 23 A6 --- Inst Instrument (1)
25- 32 A8 "YYYY/MMM" Date Observation date
34- 35 I2 --- Ng [2/50]? Number of galaxies used in
deriving redshifts
37- 40 A4 --- Ref Reference(s) (2)
--------------------------------------------------------------------------------
Note (1): Instruments (Inst):
GMOS-S = Gemini Multi-Object Spectrograph South 8m telescope
IMACS = Inamori-Magellan Areal Camera & Spectrograph on Magellan
Baade 6.5m telescope
GISMO = Gladders Image-Slicing Multislit Option, complement to IMACS
on Magellan Baade 6.5m telescope
LDSS3 = Low Dispersion Survey Spectrograph at Magellan Clay 6.5m telescope
FORS2 = FOcal Reducer and low dispersion Spectrograph at VLT 8m telescope
Note (2): Reference as follows:
a = Stalder et al. (2013ApJ...763...93S 2013ApJ...763...93S),
b = Williamson et al. (2011ApJ...738..139W 2011ApJ...738..139W),
c = Struble & Rood (1999ApJS..125...35S 1999ApJS..125...35S),
d = High et al. (2010ApJ...723.1736H 2010ApJ...723.1736H),
e = Sifon et al. (2013ApJ...772...25S 2013ApJ...772...25S),
f = Boehringer et al. (2004, Cat. J/A+A/425/367),
g = Brodwin et al. (2010ApJ...721...90B 2010ApJ...721...90B),
h = Buckley-Geer et al. (2011, Cat. J/ApJ/742/48),
i = Foley et al. (2011ApJ...731...86F 2011ApJ...731...86F).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 A6 --- --- [SPT-CL]
7- 16 A10 --- SPT-CL SPT cluster identification (JHHMM+DDMM)
18 A1 --- n_SPT-CL Note on SPT-CL cluster (1)
20- 27 F8.4 deg RAdeg Right ascension (J2000)
29- 36 F8.4 deg DEdeg [-65.2/-44.8] Declination (J2000)
38- 42 F5.2 --- xi [4.5/22.1] Detection significance ξ (2)
44- 48 F5.3 --- z [0.05/1.4]? Spectroscopic redshift (3)
50 A1 --- l_zcomb Limit flag on zcomb
52- 55 F4.2 --- zcomb [0.07/1.5] combined redshift, or lower limit
57- 60 F4.2 --- e_zcomb [0.02/0.09]? zcomb uncertainty
62- 63 A2 --- q_zcomb Photometric redshift quality flag (1=secure) (4)
65- 68 F4.1 % PNF ? NEWFIRM NIR blank field probability (5)
70- 73 F4.1 % PSp ? Spitzer NIR blank field probability (5)
75- 79 F5.1 % PW ? WISE NIR blank field probability (5)
81- 88 F8.4 deg RABdeg ? Red brightest cluster galaxy (rBCG) right
ascension (J2000)
90- 97 F8.4 deg DEBdeg ? Red brightest cluster galaxy (rBCG)
declination (J2000)
99-101 A3 --- Obs Imaging reference(s) (6)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
e = Optical group on N z∼0.3.
f = Optical only z∼1.0.
g = Very complex region, optical group on NW z∼0.4,
another group on SW z∼0.65.
h = Optical group within 1' aperture z∼0.35.
i = Strong-lensing arc.
j = Strong-lensing arc.
k = Optical group on SW z∼0.4.
l = Optical group within 1' aperture z∼0.15.
m = Optical group on SE z∼0.4.
Note (2): Twelve different matched filters are used, each assuming a
different scale radius for the cluster, and the maximum signal to
noise for a given candidate across all filter scales is referred to as
ξ, which we use as our primary Sunyaev-Zel'dovich (SZ) observable.
See section 2.1.
Note (3): Spectroscopic redshift listed where available. Details on
references and observations are given in Table 2.
Note (4): Photometric redshift quality flag as follows:
1 = secure;
2 = statistically inconsistent between three methods;
3 = Swope or Spitzer/IRAC colors only used;
4 = only one method used (except Swope and Spitzer-only cases).
3* = has larger bias correction (SWOPE only photometric redshift;
see the text for more detail).
Note (5): Probability of finding a random position in the sky richer than
the SPT cluster candidate, using single-band NIR galaxy overdensity.
Only calculated for unconfirmed candidates and confirmed clusters at
z>0.7.
Note (6): Cross-reference to imaging data. Only the deepest imaging data
source is noted in this table. Internal references "Obs" refer to
Table 1. Obs. 1* indicates that Blanco Cosmology Survey (BCS; Desai
et al. 2012, Cat. J/ApJ/757/83) imaging data were used.
-----------------------------------------------------------------------------
Table 1: Optical and infrared cameras used in SPT follow-up observations:
-----------------------------------------------------------------------------
Obs Site Telescope Ap. Camera Filt Field Pixel Scale
(m) (")
-----------------------------------------------------------------------------
1 Cerro Tololo Blanco 4 MOSAIC-II griz 36x36" 0.27
2 Las Campanas Magellan/Baade 6.5 IMACS f/2 griz 27.4x27.4' 0.200
3 Las Campanas Magellan/Clay 6.5 LDSS3 griz 8.3' diam. 0.189
4 Las Campanas Magellan/Clay 6.5 Megacam gri 25x25" 0.16
5 Las Campanas Swope 1 SITe3 BVRI 14.8x22.8' 0.435
6 Cerro Tololo Blanco 4 NEWFIRM Ks 28x28" 0.4
7 Spitzer 0.85 IRAC 3.6,4.5um 5.2x5.2' 1.2
8 WISE 0.40 3.4,4.6um 47x47" 6
-----------------------------------------------------------------------------
Filt: Not all filters were used on every cluster.
Obs #4: Megacam data were acquired for a large follow-up weak-lensing program
-----------------------------------------------------------------------------
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 31-Jul-2014