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J/ApJ/779/65    Photometry of LBGs, LAEs and GNBs at z∼2.85    (Mostardi+, 2013)

Narrowband Lyman-continuum imaging of galaxies at z∼2.85. Mostardi R.E., Shapley A.E., Nestor D.B., Steidel C.C., Reddy N.A., Trainor R.F. <Astrophys. J., 779, 65 (2013)> =2013ApJ...779...65M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Photometry, UBV ; Photometry, ultraviolet ; Redshifts Keywords: cosmology: observations - diffuse radiation - galaxies: high-redshift - intergalactic medium Abstract: We present results from a survey for z∼2.85 Lyman-continuum (LyC) emission in the HS1549+1933 field and place constraints on the amount of ionizing radiation escaping from star-forming galaxies. Using a custom narrowband filter (NB3420) tuned to wavelengths just below the Lyman limit at z≥2.82, we probe the LyC spectral region of 49 Lyman break galaxies (LBGs) and 91 Lyα emitters (LAEs) spectroscopically confirmed at z≥2.82. Four LBGs and seven LAEs are detected in NB3420. Using V-band data probing the rest-frame nonionizing UV, we observe that many NB3420-detected galaxies exhibit spatial offsets between their LyC and nonionizing UV emission and are characterized by extremely blue NB3420-V colors, corresponding to low ratios of nonionizing to ionizing radiation (FUV/FLyC) that are in tension with current stellar population synthesis models. We measure average values of (FUV/FLyC) for our LBG and LAE samples, correcting for foreground galaxy contamination and H I absorption in the intergalactic medium. We find (FUV/FLyC)corrLBG=82±45 and (FUV/FLyC)corrLAE=7.4±3.6. These flux density ratios correspond, respectively, to relative LyC escape fractions of fesc,relLBG=5%-8%, and fesc,relLAE=18%-49% absolute LyC escape fractions of fesc,relLBG=1%-2% and fesc,relLAE=5%-15%, and a comoving LyC emissivity from star-forming galaxies of 8.8-15.0x1024 erg/s/Hz/Mpc3. In order to study the differential properties of galaxies with and without LyC detections, we analyze narrowband Lyα imaging and rest-frame near-infrared imaging, finding that while LAEs with LyC detections have lower Lyα equivalent widths on average, there is no substantial difference in the rest-frame near-infrared colors of LBGs or LAEs with and without LyC detections. These preliminary results are consistent with an orientation-dependent model where LyC emission escapes through cleared paths in a patchy interstellar medium. Description: We performed multi-object spectroscopy in 2011 May on the Keck 1 telescope, using the blue side of LRIS. We observed four slitmasks with exposure times of 16560, 9000, 8400, and 8100 s, respectively. For all masks, we used the 400 line/mm grism blazed at 3400 Å, achieving a spectral resolution of R=800 for 1.2" slits. The "d500" dichroic beam splitter was used for the first mask (originally designed for deep LyC spectroscopy) and the "d560" dichroic was used for the three additional masks (designed to acquire redshifts). The conditions during the observing run were suboptimal, with intermittent clouds and a seeing FWHM of 0.7"-1.0" during clear spells. When designing the slitmasks, we targeted both LBGs and LAEs with NB3420 detections. Slits were centered on the coordinates of the V (NB4670) centroid for LBGs (LAEs). While most LAEs were selected using the V-band image as the continuum band, a small fraction (20%) were selected using the G-band (henceforth referred to as GNBs). Overall, we observed 46 objects on the four slitmasks, 29 of which had repeat observations. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 104 49 LBG Photometry table4.dat 104 91 LAE Photometry table8.dat 104 8 Photometry for GNBs and LAEs with m4670>26.0 table9.dat 104 33 Photometry for LAE Photometric Candidates
See also: J/A+A/498/13 : Lyman-α emitters from redshifts z∼2-3 (Nilsson+, 2009) J/ApJ/736/18 : Lyman-continuum emission at z∼3 in SSA22 field (Nestor+, 2011) J/ApJ/744/110 : LAE galaxies between 2.1=<z≤3.1 (Ciardullo+, 2012) J/ApJ/765/47 : Lyman-break galaxies and LAEs at z∼3 (Nestor+, 2013) J/A+A/563/A142 : UGR photometry of LBG candidates at z∼3 (Boutsia+, 2014) J/ApJ/810/107 : Lyman break galaxies and LAEs HST photometry (Mostardi+, 2015) Byte-by-byte Description of file: table3.dat table4.dat table8.dat table9.dat
Bytes Format Units Label Explanations
1- 4 A4 --- LBG LBG identifier (only in table3) (1) 6- 8 A3 --- --- [lae] 9- 12 I4 --- lae [32/7893]? LAE identifier (laeNNNN) (not in table3) 13 A1 --- n_lae [efghijklm] Note on lae (2) 15- 17 A3 --- --- [GNB] 18- 21 I4 --- GNB [2861/5270]? GNB (G narrowband filter (NB4670) selected LAE) identifier (GNBNNNN) (only in table8) 23- 24 I2 h RAh Hour of Right Ascension (J2000) (3) 26- 27 I2 min RAm Minute of Right Ascension (J2000) (3) 29- 34 F6.3 s RAs Second of Right Ascension (J2000) (3) 35 A1 --- DE- Sign of the Declination (J2000) (3) 36- 37 I2 deg DEd Degree of Declination (J2000) (3) 39- 40 I2 arcmin DEm Arcminute of Declination (J2000) (3) 42- 46 F5.2 arcsec DEs Arcsecond of Declination (J2000) (3) 48- 52 F5.3 --- z ? Redshift 54- 58 F5.3 --- z(em) ? Emission redshift of Lyα 60- 64 F5.3 --- z(abs) ? Interstellar absorption redshift 66- 70 F5.2 mag NB4670mag ? KeckI/LRIS-B NB4670 AB magnitude 72 A1 --- l_Vmag [>] Limit flag on Vmag 73- 77 F5.2 mag Vmag KeckI/LRIS-R V-band AB magnitude 79 A1 --- l_NB3420mag [>] Limit flag on NB3420mag 80- 84 F5.2 mag NB3420mag KeckI/LRIS-B NB3420 AB magnitude 86- 89 F4.2 arcsec DelUV ? Spatial offset between the centroid of V-band and NB3420 emission, ΔUV,LyC 91- 94 F4.2 arcsec DelLy ? Spatial offset between the centroid of NB4760 and NB3420 emission, ΔLyα,LyC 96 A1 --- l_FUV/FLyC [>] Limit flag on FUV/FLyC 97-100 F4.1 --- FUV/FLyC ? Observed ratio of nonionizing UV to LyC flux-densities, inferred from the NB3420-V color (4) 102-104 F3.1 --- e_FUV/FLyC ? Uncertainty in FUV/FLyC
Note (1): LBG identifiers are BXNN, MDNN, CNN, DNN and MNN. Note (2): Note as follows: e = D4; f = C4; g = D7; h = C13; i = C15; j = MD12. This object is not included in either the LAE or LBG samples; k = D19; l = D18; m = D17. Note (3): Coordinates of LAEs and GNBs are based on NB4670 centroids. Note (4): This value has not been corrected for either contamination by foreground sources or IGM absorption.
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 17-Nov-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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