J/ApJ/736/48 48 Lyman break galaxies at z∼3 in HUDF (Rafelski+, 2011)
Star formation from DLA gas in the outskirts of Lyman break galaxies at z ∼ 3.
Rafelski M., Wolfe A.M., Chen H.-W.
<Astrophys. J., 736, 48 (2011)>
=2011ApJ...736...48R 2011ApJ...736...48R
ADC_Keywords: Galaxies, photometry ; Redshifts ; Photometry, UBV
Keywords: cosmology: observations - galaxies: evolution - galaxies: general -
galaxies: high-redshift - galaxies: photometry -
quasars: absorption lines
Abstract:
We present evidence for spatially extended low surface brightness
emission around Lyman break galaxies (LBGs) in the V-band image of the
Hubble Ultra Deep Field, corresponding to the z∼3 rest-frame far-UV
(FUV) light, which is a sensitive measure of star formation rates
(SFRs). We find that the covering fraction of molecular gas at z∼3 is
not adequate to explain the emission in the outskirts of LBGs, while
the covering fraction of neutral atomic-dominated hydrogen gas at high
redshift is sufficient. We develop a theoretical framework to connect
this emission around LBGs to the expected emission from neutral HI
gas, i.e., damped Lyα systems (DLAs), using the
Kennicutt-Schmidt (KS) relation. Working under the hypothesis that the
observed FUV emission in the outskirts of LBGs is from in situ star
formation in atomic-dominated hydrogen gas, the results suggest that
the SFR efficiency in such gas at z∼3 is between factors of 10 and 50
lower than predictions based on the local KS relation. The total SFR
density in atomic-dominated gas at z∼3 is constrained to be ∼10% of
that observed from the inner regions of LBGs. In addition, the metals
produced by in situ star formation in the outskirts of LBGs yield
metallicities comparable to those of DLAs, which is a possible
solution to the "Missing Metals" problem for DLAs. Finally, the
atomic-dominated gas in the outskirts of galaxies at both high and low
redshifts has similar reduced SFR efficiencies and is consistent with
the same power law.
Description:
High angular resolution (point-spread function (PSF) FWHM=0.09")
V-band images of the Hubble UDF taken with the HST were used for this
work. We also acquired one of the most sensitive u-band images ever
obtained and identified 407 LBGs at z∼3 (Rafelski et al. 2009, Cat.
J/ApJ/703/2033; see also Nonino et al. 2009ApJS..183..244N 2009ApJS..183..244N).
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 on the HST Advanced Camera for Surveys (ACS).
The u-band image was obtained with the Keck I Telescope and the blue
channel of the Low Resolution Imaging Spectrometer (LRIS).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 73 48 Properties of Lyman-Break Galaxies (LBGs)
included in image stack
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/258 : Hubble Ultra Deep Field Catalog (UDF) (STScI, 2004)
J/ApJ/735/L22 : HUDF galaxy properties at z∼2 (Szomoru+, 2011)
J/ApJ/703/2033 : Lyman-break galaxies (LBG) in the HUDF (Rafelski+, 2009)
J/AJ/132/1729 : Hubble Ultra Deep Field BVI-dropout sources (Beckwith+, 2006)
J/AJ/132/1023 : U-band dropouts in Hubble Ultra Deep Field (Wadadekar+, 2006)
J/AJ/132/926 : Galaxies in the Hubble Ultra Deep Field (Coe+, 2006)
J/AJ/130/1 : Catalog of source parameters in NICMOS UDF (Thompson+, 2005)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- [CBS2006] [84/60302] Corresponds to Coe et al. catalog (1)
7- 10 F4.2 --- zb [2.5/3.5] Bayesian Photometric-Z
most likely redshift
12- 15 F4.2 --- e_zb Lower limit (95% confidence)
17- 20 F4.2 --- E_zb Upper limit (95% confidence)
22- 26 F5.2 mag Vmag [25.0/27.6] HST V band AB magnitude
28- 31 F4.2 mag e_Vmag Uncertainty in Vmag
33- 36 F4.2 mag u'-V The (u'-V) color index
38- 41 F4.2 mag e_u'-V Uncertainty in u'-V
43- 47 F5.2 mag B-V The (B-V) color index
49- 52 F4.2 mag e_B-V Uncertainty in B-V
54- 58 F5.2 mag V-z' The (V-z') color index
60- 63 F4.2 mag e_V-z' Uncertainty in V-z'
65- 68 F4.2 arcsec FWHM [0.1/0.24] FWHM of LBG as measured by SExtractor
70- 73 F4.2 --- Ell [0.01/0.25] Ellipticity of LBG as measured by
SExtractor
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Note (1): ID's from Rafelski et al. 2009, Cat. J/ApJ/703/2033 (which take IDs
from Coe et al. 2006, Cat. J/AJ/132/926) and correspond to
other IDs in the following way:
* ID's < 40000 correspond to Beckwith et al. 2006, Cat. J/AJ/132/1729,
ACS catalog (see also cat. II/258);
* 40001-41000 correspond to Thompson et al. 2005, Cat. J/AJ/130/1,
v.1 NIC3 catalog +40000;
* ID's > 50000 correspond to Coe et al., 2006, Cat. J/AJ/132/926;
<[CBS2006] NNNNN> in Simbad.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Dec-2012