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J/ApJ/703/2033         Lyman-break galaxies (LBG) in the HUDF  (Rafelski+, 2009)

Deep Keck u-band imaging of the Hubble Ultra Deep Field: a catalog of z ∼ 3 Lyman break galaxies. Rafelski M., Wolfe A.M., Cooke J., Chen H.-W., Armandroff T.E., Wirth G.D. <Astrophys. J., 703, 2033-2050 (2009)> =2009ApJ...703.2033R
ADC_Keywords: Galaxy catalogs ; Redshifts ; Photometry, narrow-band ; Photometry, HST Keywords: cosmology: observations - galaxies: distances and redshifts - galaxies: evolution - galaxies: general - galaxies: high-redshift - galaxies: photometry Abstract: We present a sample of 407 z∼3 Lyman break galaxies (LBGs) to a limiting isophotal u-band magnitude of 27.6mag in the Hubble Ultra Deep Field. The LBGs are selected using a combination of photometric redshifts and the u-band drop-out technique enabled by the introduction of an extremely deep u-band image obtained with the Keck I telescope and the blue channel of the Low Resolution Imaging Spectrometer. The Keck u-band image, totaling 9hr of integration time, has a 1σ depth of 30.7mag/arcsec2, making it one of the most sensitive u-band images ever obtained. The u-band image also substantially improves the accuracy of photometric redshift measurements of ∼50% of the z∼3 LBGs, significantly reducing the traditional degeneracy of colors between z∼3 and z∼0.2 galaxies. Description: The u-band (λ0∼3400Å, FWHM∼690Å) images of the UDF (J033239-274729) were obtained with the 10m Keck I telescope using the LRIS. The observations were carried out in dark time over two runs, 2007 October 7-9 (three half nights) and 2007 December 3-4 (two half nights). Throughout the paper, we utilize the B, V, i', and z' band (F435W, F606W, F775W, and F850LP, respectively) observations of the UDF (Beckwith et al. 2006, Cat. J/AJ/132/1729), obtained with the Wide Field Camera (WFC) on the HST Advance Camera for Surveys (ACS). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 85 1458 Catalog of u-band objects table2.dat 119 1458 Catalog of Bayesian photometric redshifts table3.dat 108 100 Catalog of galaxies with reliable spectroscopic redshifts in the UDF table4.dat 96 407 Catalog of z∼3 LBGs in the UDF
See also: B/hst : HST Archived Exposures Catalog (STScI, 2007) II/258 : Hubble Ultra Deep Field Catalog (UDF) (STScI, 2004) J/A+A/478/83 : GOODS-South Field VLT/FORS2 redshifts. III. (Vanzella+, 2008) J/AJ/134/169 : Redshifts of UDF emission-line objects (Xu+, 2007) J/AJ/132/1729 : Hubble Ultra Deep Field BVI-dropout sources (Beckwith+, 2006) J/AJ/132/926 : Galaxies in the Hubble Ultra Deep Field (Coe+, 2006) J/A+A/454/423 : GOODS-South Field VLT/FORS2 redshifts. II. (Vanzella+, 2006) J/ApJ/639/724 : Tadpole galaxies in the Hubble UDF (Straughn+, 2006) J/AJ/130/1 : Catalog of source parameters in NICMOS UDF (Thompson+, 2005) J/A+A/434/53 : GOODS-South Field redshifts (Vanzella+, 2005) J/ApJS/150/1 : VV29 and NGC 4676 HST photometry (Benitez+, 2004) J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004) J/ApJS/155/271 : Chandra Deep Field-South: Optical spectroscopy (Szokoly+, 2004) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 I5 --- [CBS2006] ID from Coe et al. catalog (G1) 8- 18 F11.8 deg RAdeg Right Ascension in decimal degrees (J2000) 21- 32 F12.8 deg DEdeg Declination in decimal degrees (J2000) 35- 39 F5.2 mag umag KeckI/LRIS u-band (~3400AA) total magnitude (1) 42- 45 F4.2 mag e_umag σ of magnitude in u-band 48- 54 F7.2 --- S/N Signal to noise ratio of u-band flux 57- 61 I5 --- CovID ID of most significant neighbor affecting photometry 64- 68 F5.3 --- CovIdx Absolute value of ratio of Variance and covariance 71- 77 F7.3 --- FRatio Ratio of V-band fluxes of object and most significant neighbor 80- 85 F6.3 arcsec Dist Distance to most significant neighbor
Note (1): Total u-band magnitudes for the same aperture as the V-band in Coe et al. 2006, Cat. J/AJ/132/926.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 I5 --- [CBS2006] ID from Coe et al. catalog (G1) 8- 11 F4.2 --- zb Bayesian Photo-Z (BPZ) most likely redshift 14- 17 F4.2 --- b_zb Lower limit (95% confidence) in zb 20- 23 F4.2 --- B_zb Upper limit (95% confidence) in zb 26- 29 F4.2 --- tb BPZ most likely spectral type (1) 32- 36 F5.3 --- odds P(z) contained within 0.1*(1+zb) (2) 39- 44 F6.2 --- chinu Quality of BPZ fit: observed vs. model fluxes 47- 52 F6.2 --- chimod Modified chi2 (includes model uncertainties) 55- 58 F4.2 --- zb1 BPZ most-likely redshift 61- 64 F4.2 --- b_zb1 Lower bound zb1min for highest peak in P(z) 67- 70 F4.2 --- B_zb1 Upper bound zb1max for highest peak in P(z) 73- 76 F4.2 --- tb1 [1/8] BPZ most-likely spectral type (2) 79- 83 F5.3 --- odds1 P(z) between zb1min and zb1max 86- 90 F5.2 --- zb2 ?=-1 BPZ 2nd-most-likely redshift (3) 93- 97 F5.2 --- b_zb2 ?=-1 Lower bound for 2nd-highest peak in P(z) (3) 100-104 F5.2 --- B_zb2 ?=-1 Upper bound for 2nd-highest peak in P(z) (3) 107-111 F5.2 --- tb2 ?=-1 BPZ 2nd-most-likely spectral type (2)(3) 114-119 F6.3 --- odds2 ?=-1 P(z) between zb2min and zb2max (3)
Note (1): SED template type (tb) can be useful when selecting a specific type of galaxy, where 1=El, 2=Scd, 3=Sbc, 4=Im (cww types from Coleman, Wu and Weedman 1980ApJS...43..393C) 5=SB3, 6=SB2 (from Kinney et al. 1996ApJ...467...38K), 7=25Myr, and 8=5Myr. For instance, in selecting LBGs we constrain ourselves to galaxies with tb>3, which only include star-forming galaxy templates. A re-calibration of the SED template set improves the performance of the photometric redshifts, and we use the re-calibrated SED templates from Benitez et al. (2004, Cat. J/ApJS/150/1) and Coe et al. (2006, Cat. J/AJ/132/926) that have been extensively tested with BPZ. These re-calibrated SEDs are based on the star-forming (Im), spiral (Scd, Sbc), and elliptical (El) galaxy templates from Coleman et al. (1980ApJS...43..393C), the star bursting galaxy templates with different reddening (SB2, SB3) from Kinney et al. (1996ApJ...467...38K), and the faint blue galaxy SEDs with ages of 25 and 5Myr and metallicities of Z=0.08 without dust from Bruzual & Charlot (2003MNRAS.344.1000B), described in section Section 4.1 of Coe et al. (2006, Cat. J/AJ/132/926). Note (2): For each galaxy, z-phot codes produce a probability distribution function, P(z), representing the probability of a galaxy being at any specific redshift. However, the P(z) can have multiple peaks, especially at z∼3 where there is a degeneracy with galaxies at z∼0.2, which then translates into large uncertainties for the z-phot (Benitez 2000ApJ...536..571B). Note (3): -1.0 denotes an empty field in the table if only 1 peak in P(z).
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 5 I5 --- [CBS2006] ID from Coe et al. catalog (G1) 8- 14 A7 --- r_zsp Denotes the survey for zsp (1) 17- 20 F4.2 --- zsp Spectroscopic redshift 23- 26 F4.2 --- zb BPZ most likely redshift 29- 32 F4.2 --- e_zb Lower limit (95% confidence) in zb 35- 38 F4.2 --- E_zb Upper limit (95% confidence) in zb 41- 45 F5.2 --- chimod Modified chi2 (includes model uncertainties) 48- 51 F4.2 --- odds P(z) contained within 0.1*(1+zb) 54- 59 F6.2 mag Vmag Total V band AB magnitude (2) 62- 66 F5.2 mag e_Vmag σ uncertainty in Vmag 69- 73 F5.2 mag u-V (u-V) isophotal color index (2) 76- 80 F5.2 mag e_u-V σ uncertainty in u-V 83- 87 F5.2 mag u-B (u-B) isophotal color index (2) 90- 94 F5.2 mag e_u-B σ uncertainty in u-B 97-101 F5.2 mag V-z' (V-z') isophotal color index (2) 104-108 F5.2 mag e_V-z' σ uncertainty in V-z'
Note (1): Redshift surveys as follows: VVDS = Fevre et al. 2004, Cat. J/A+A/428/1043; <VCDFS NNNNNN> in Simbad. VIMOS = Popesso et al. 2009A&A...494..443P, Szokoly = Szokoly et al. 2004, Cat. J/ApJS/155/271 FORS2 = Vanzella et al. 2005, Cat. J/A+A/434/53, 2006, Cat. J/A+A/454/423, 2008, Cat. J/A+A/478/83 and 2009ApJ...695.1163V. Note (2): All photometry other than the u-band are from Coe et al. (2006, Cat. J/AJ/132/926). Nondetections in u-band are given 3σ limiting magnitudes.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 5 I5 --- [CBS2006] ID from Coe et al. catalog (G1) 8- 11 F4.2 --- zb BPZ most likely redshift 14- 17 F4.2 --- e_zb Lower limit (95% confidence) in zb 20- 23 F4.2 --- E_zb Upper limit (95% confidence) in zb 26- 30 F5.2 --- chimod Modified chi2: includes model uncertainties 33- 36 F4.2 --- odds P(z) contained within 0.1*(1+zb) 39 I1 --- type [1,3] Type of LBG selection (1) 42- 47 F6.2 mag Vmag Total V band AB magnitude (2) 50- 54 F5.2 mag e_Vmag σ uncertainty in Vmag 57- 61 F5.2 mag u-V (u-V) isophotal color (2) 64- 68 F5.2 mag e_u-V σ uncertainty in u-V 71- 75 F5.2 mag u-B (u-B) isophotal color (2) 78- 82 F5.2 mag e_u-B σ uncertainty in u-B 85- 89 F5.2 mag V-z' (V-z') isophotal color (2) 92- 96 F5.2 mag e_V-z' σ uncertainty in V-z'
Note (1): LBG selection type as follows: 1 = Both color selection and photometric redshift. 2 = Photometric redshift; 3 = Color selection. Note (2): All photometry other than the u-band are from Coe et al. (2006, Cat. J/AJ/132/926). Nondetections in u-band are given 3σ limiting magnitudes.
Global notes: Note (G1): Identifications correspond to: * 1-40000 correspond to Beckwith et al. ACS catalog (2006, Cat. J/AJ/132/1729); * 40001-41000 correspond to Thompson et al. v.1 NIC3 catalog (2006pces.conf..195T, see also Cat. J/AJ/130/1). * >50000 correspond to Coe et al, 2006, Cat. J/AJ/132/926; <[CBS2006] NNNNN> in Simbad.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Nov-2011
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