J/AJ/160/37 Intergalac. medium opacity from Lyman-break galaxies (Monzon+, 2020)
Effective opacity of the intergalactic medium from galaxy spectra analysis.
Monzon J.S., Prochaska J.X., Lee K.-G., Chisholm J.
<Astron. J., 160, 37 (2020)>
=2020AJ....160...37M 2020AJ....160...37M
ADC_Keywords: Galaxies; Star Forming Region; Intergalactic medium; Opacities;
Redshifts; Spectra, optical
Keywords: Intergalactic medium ; Intergalactic gas ; Lyman-break galaxies
Abstract:
We measure the effective opacity (τeff) of the intergalactic
medium from the composite spectra of 281 Lyman-break galaxies in the
redshift range 2≲z≲3. Our spectra are taken from the COSMOS
Lyα Mapping And Tomographic Observations survey derived from the
Low Resolution Imaging Spectrometer on the W.M. Keck I telescope. We
generate composite spectra in two redshift intervals and fit them with
spectral energy distribution (SED) models composed of simple stellar
populations. Extrapolating these SED models into the Lyα forest,
we measure the effective Lyα opacity (τeff) in the
2.02≲z≲2.44 range. At z=2.22, we estimate τeff=0.159±0.001
from a power-law fit to the data. These measurements are consistent
with estimates from quasar analyses at z<2.5 indicating that the
systematic errors associated with normalizing quasar continua are not
substantial. We provide a Gaussian processes model of our results and
previous τeff measurements that describes the steep redshift
evolution in τeff from z=1.5-4.
Description:
Our sample of galaxies was drawn from the 2016 and 2017 releases of
the COSMOS Lyα Mapping And Tomographic Observations (CLAMATO),
which were measured by the Low Resolution Imaging Spectrometer (LRIS)
on the W.M. Keck I telescope.
Observations for CLAMATO lasted a total of 15.5 nights, during which
about 60hr were spent on sky with a typical total exposure time per
object lasting ∼9000s. LRIS was configured with the 600/4000 grism to
achieve an approximate resolution R=λ/Δλ∼1000 with
1" slits between the observer-frame wavelengths of 3700Å and
4400Å on its Blue channel.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 47 281 Sample of COSMOS Lyα Mapping And Tomographic
Observations (CLAMATO) Lyman-break galaxies (LBGs)
used in our composite analysis
tablea2.dat 21 114 Effective opacity values and corresponding 1D
errors for the zlow and zhigh redshift interval
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See also:
J/ApJ/596/768 : Optical depths in 19 QSOs (Schaye+, 2003)
J/ApJ/662/72 : Lyman alpha forest of 55 QSOs (Becker+, 2007)
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/A+A/530/A50 : Principal Component Analysis of QSO UV spectra (Paris+,2011)
J/MNRAS/445/1745 : Giant Gemini GMOS survey. I. (Worseck+, 2014)
J/ApJ/828/21 : ZFIRE v1.0 data release (Nanayakkara+, 2016)
J/ApJ/862/96 : Star-forming galaxies with LABOCA 870um obs. (Lewis+, 2018)
J/ApJS/237/31 : CLAMATO DR1: 3D Lyα forest tomography (Lee+, 2018)
J/A+A/633/A159 : Bright Lyman-alpha emitters in MUSE/COSMOS (Rosani+, 2020)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- ID CLAMATO identification of the galaxy
25- 33 F9.5 deg RAdeg [149/151] Degree of right ascension (J2000)
35- 41 F7.5 deg DEdeg [2.13/2.5] Degree of declination (J2000)
43- 47 F5.3 --- z [2.25/2.75] Redshift
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 6 F6.4 --- z [2.02/2.45] Redshift
8- 14 F7.4 --- tau [-0.004/0.38] Effective opacity (τeff)
16- 21 F6.4 --- e_tau [0.03/0.1] Error on tau (τσ)
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History:
From electronic version of the journal
(End) Prepared by Coralie Fix [CDS], 09-Dec-2020