J/ApJ/760/128 Ly{alpha} emission from 4 =2012ApJ...760..128M ================================================================================ ADC_Keywords: Equivalent widths ; Galaxies, spectra ; Redshifts Keywords: galaxies: evolution; galaxies: high-redshift; galaxies: ISM Abstract: We investigate spectroscopically measured Ly{alpha} 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 Ly{alpha} 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 Ly{alpha} 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 Ly{alpha} 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 ~6000-9000{AA}. 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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 110 239 Ly{alpha} emission table4.dat 102 244 Best-fit model SED parameters -------------------------------------------------------------------------------- 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~} 4 (Steidel+, 1999) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- 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] Ly{alpha} Flux (in 10^-18^erg/cm^2^/s = 10^-21^W/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 Ly{alpha} rest-frame equivalent width (in {AA}) 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] Ly{alpha} 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 -------------------------------------------------------------------------------- Note (1): the flux is fitted to a skewed Gaussian Flux=A.exp[-0.5(({lambda}-x)/{omega})^2^].G(s({lambda}-x)/{omega})+c where G(x) is the error function ({int}exp(-t^2^)/2); the moments of the skewed Gaussian are {lambda}_0_=x+{omega}{delta}sqrt(2/{pi}), and {sigma}={omega}sqrt(1-2{delta}^2^/{pi}), where {delta}=s/sqrt(1+s^2^) -------------------------------------------------------------------------------- Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- 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 {chi}^2^ 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 -------------------------------------------------------------------------------- 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