J/ApJ/760/128 Lyα emission from 4<z<6 sources in COSMOS (Mallery+, 2012)
Lyα emission from high-redshift sources in COSMOS.
Mallery R.P., Mobasher B., Capak P., Kakazu Y., Masters D., Ilbert O.,
Hemmati S., Scarlata C., Salvato M., McCracken H., Lefevre O., Scoville N.
<Astrophys. J., 760, 128 (2012)>
=2012ApJ...760..128M 2012ApJ...760..128M
ADC_Keywords: Equivalent widths ; Galaxies, spectra ; Redshifts
Keywords: galaxies: evolution; galaxies: high-redshift; galaxies: ISM
Abstract:
We investigate spectroscopically measured Lyα equivalent widths
(EWs) and escape fractions of 244 sources of which 95 are Lyman break
galaxies (LBGs) and 106 Lyman alpha emitters (LAEs) at z∼4.2, z∼4.8,
and z∼5.6 selected from intermediate and narrowband observations. The
sources were selected from the Cosmic Evolution Survey and observed
with the DEIMOS spectrograph. We find that the distribution of EWs
shows no evolution with redshift for both the LBG selected sources and
the intermediate/narrowband LAEs. We also find that the Lyα
escape fraction of intermediate/narrowband LAEs is on average higher
and has a larger variation than the escape fraction of LBG selected
sources. The escape fraction does not show a dependence with redshift.
Similar to what has been found for LAEs at low redshifts, the sources
with the highest extinctions show the lowest escape fractions. The
range of escape fractions increases with decreasing extinction. This
is evidence that the dust extinction is the most important factor
affecting the escape of Lyα photons, but at low extinctions
other factors, such as the H I covering fraction and gas kinematics,
can be just as effective at inhibiting the escape of Lyα
photons.
Description:
Full details of the observations and data obtained with Keck/DEIMOS
can be found in P. Capak et al. (2012, in preparation). The
observations were taken over a period of several semesters with five
nights in 2007 January, four nights in 2008 November, four nights in
2009 November, seven nights in 2010 January, and five nights in 2010
February, with a wavelength coverage of ∼6000-9000Å.
Multi-bandpass Subaru photometry was used, consisting of broad (r, i,
z), narrow (NB711, NB816), and intermediate (IB624, IB709, IB738,
IB767) band filters from the publicly available COSMOS optical catalog
(see Capak et al. 2007, Cat. II/284).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 110 239 Lyα emission
table4.dat 102 244 Best-fit model SED parameters
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See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
J/A+A/544/A156 : UltraVISTA Catalogue Release DR1 (McCracken+, 2012)
J/ApJ/736/31 : HETDEX pilot survey. II. 1.9<z<3.8 LAEs (Blanc+, 2011)
J/ApJ/725/394 : High-redshift Lyα emitters (Hu+, 2010)
J/ApJ/721/1 : Keck ESI observations of Lyα systems (Penprase+, 2010)
J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)
J/ApJ/706/762 : LAEs at z∼4.5 in the LALA Cetus field (Wang+, 2009)
J/ApJ/696/546 : Lyα emitters at z∼4.86 (Shioya+, 2009)
J/A+A/498/13 : Lyman-α emitters from redshifts z∼2-3 (Nilsson+, 2009)
J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS (Cappelluti+, 2009)
J/ApJS/176/301 : Subaru/XMM-Newton deep survey IV. (SXDS) (Ouchi+, 2008)
J/ApJS/172/523 : COSMOS field Lyα emitters at z∼5.7 (Murayama+, 2007)
J/ApJ/671/1227 : Lyα galaxies at z∼4.5 (Dawson+, 2007)
J/ApJ/667/79 : Lyα emission-line galaxies at z=3.1 (Gronwall+, 2007)
J/ApJ/648/7 : LAEs at z=6.5 in Subaru Deep Field (Kashikawa+, 2006)
J/ApJ/642/L13 : ECDFS MUSYC galaxies UBVRIzNB5000 photometry (Gawiser+, 2006)
J/PASJ/58/313 : Lyα emitters in the SUBARU Deep Field (Shimasaku+, 2006)
J/PASJ/57/165 : Lyα emitters in the SUBARU Deep Field (Taniguchi+, 2005)
J/AJ/127/180 : The Hawaii Hubble Deep Field North (Capak+, 2004)
J/ApJ/519/1 : Lyman-break galaxies at z ≳ 4 (Steidel+, 1999)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- ID Source identification
16- 25 F10.6 deg RAdeg [149.5/150.9] Right ascension (J2000)
27- 34 F8.6 deg DEdeg [1.5/2.93] Declination (J2000)
36- 44 A9 --- Note Type of object (LBG, QSO or AGN), filter
or "Photo-z" note
48- 52 F5.3 --- z [3.7/6.5] Redshift (spectroscopic, but
see "Note" column)
54- 58 F5.1 zW/m2 Flux [2/617] Lyα Flux
(in 10-18erg/cm2/s = 10-21W/m2)
60- 65 F6.2 zW/m2 e_Flux [1/261] Flux uncertainty
67- 71 F5.1 0.1nm EW [2.9/90.9]?=-99.9 Lyα rest-frame
equivalent width (in Å)
73- 77 F5.2 0.1nm E_EW [0.1/34]?=0 Positive error on EW
79- 83 F5.2 0.1nm e_EW [0.7/67]?=0 Negative error on EW
85- 89 F5.2 0.1nm FWHM [2.3/31] Lyα rest-frame FWHM
91- 94 F4.2 0.1nm e_FWHM [0.1/7.3] FWHM uncertainty
95 A1 --- f_FWHM [z] Unexplained flag on FWHM
97-101 F5.2 --- Skew [0/14.3]? Skew value s (1)
103-110 F8.2 --- e_Skew [0.01/10312]? Skew uncertainty
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Note (1): the flux is fitted to a skewed Gaussian
Flux=A.exp[-0.5((λ-x)/ω)2].G(s(λ-x)/ω)+c
where G(x) is the error function (∫exp(-t2)/2); the moments
of the skewed Gaussian are λ0=x+ωδsqrt(2/π), and
σ=ωsqrt(1-2δ2/π), where δ=s/sqrt(1+s2)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- ID Source identification
16- 25 F10.6 deg RAdeg [149.5/150.9] Right ascension (J2000)
27- 34 F8.6 deg DEdeg [1.5/2.93] Declination (J2000)
36- 41 F6.1 --- chi2 [0.1/3000]? Best χ2 fit
43- 45 F3.1 mag E(B-V) [0/0.5]?=0 Extinction (best E(B-V))
47- 52 F6.2 [Msun/yr] logSFR [-0.4/3.1]?=0 log median SFR
54- 59 F6.2 [Msun/yr] B_logSFR [0.2/3.6]?=0 Upper value of log SFR
61- 66 F6.2 [Msun/yr] b_logSFR [0.03/3.1]?=0 Lower value of log SFR
68- 73 F6.2 [Msun] logM [8.1/11.4]?=0 log median mass
75- 80 F6.2 [Msun] B_logM [8.1/11.9]?=0 Upper value of log Mass
82- 87 F6.2 [Msun] b_logM [7.9/11.1]?=0 Lower value of log Mass
89- 92 F4.2 Gyr Age [0.01/2.1]?=0 Median age
94- 97 F4.2 Gyr B_Age [0.01/2.3]?=0 Upper value of age
99-102 F4.2 Gyr b_Age [0.01/1.2]?=0 Lower value of age
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Nomenclature Notes:
Tables 2,4: sources are <[MMC2012] DDD.dddddd+DD.dddddd> in Simbad.
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 30-Jul-2014