7 research outputs found
Absorption Troughs of Lyman Alpha Emitters in HETDEX
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is designed to
detect and measure the redshifts of more than one million Ly emitting
galaxies (LAEs) between . In addition to its cosmological
measurements, these data enable studies of Ly spectral profiles and the
underlying radiative transfer. Using the roughly half a million LAEs in the
HETDEX Data Release 3, we stack various subsets to obtain the typical
Ly profile for the epoch and to understand their physical
properties. We find clear absorption wings around Ly emission, which
extend km both redward and blueward of the
central line. Using far-UV spectra of nearby () LAEs in the
CLASSY treasury and optical/near-IR spectra of LAEs in the
MUSE-Wide survey, we observe absorption profiles in both redshift regimes.
Dividing the sample by volume density shows that the troughs increase in higher
density regions. This trend suggests that the depth of the absorption is
dependent on the local density of objects near the LAE, a geometry that is
similar to damped Lyman- systems. Simple simulations of Ly
radiative transfer can produce similar troughs due to absorption of light from
background sources by HI gas surrounding the LAEs.Comment: 15 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Absorption Troughs of Lyα Emitters in HETDEX
The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) is designed to detect and measure the redshifts of more than 1 million Lyα emitting galaxies (LAEs) 1.88 < z < 3.52. In addition to its cosmological measurements, these data enable studies of Lyα spectral profiles and the underlying radiative transfer. Using the roughly half a million LAEs in the HETDEX Data Release 3, we stack various subsets to obtain the typical Lyα profile for the z ∼ 2-3 epoch and to understand their physical properties. We find clear absorption wings around Lyα emission, which extend ∼2000 km s−1 both redward and blueward of the central line. Using far-UV spectra of nearby (0.002 < z < 0.182) LAEs in the COS Legacy Archive Spectroscopic Survey treasury and optical/near-IR spectra of 2.8 < z < 6.7 LAEs in the Multi Unit Spectroscopic-Wide survey, we observe absorption profiles in both redshift regimes. Dividing the sample by volume density shows that the troughs increase in higher-density regions. This trend suggests that the depth of the absorption is dependent on the local density of objects near the LAE, a geometry that is similar to damped Lyα systems. Simple simulations of Lyα radiative transfer can produce similar troughs due to absorption of light from background sources by H i gas surrounding the LAEs
HETDEX Public Source Catalog 1 -- Stacking 50K Lyman Alpha Emitters
We describe the ensemble properties of the Lyman Alpha
Emitters (LAEs) found in the HETDEX survey's first public data release, HETDEX
Public Source Catalog 1 (Mentuch Cooper et al. 2023). Stacking the
low-resolution ( 800) spectra greatly increases the signal-to-noise
ratio, revealing spectral features otherwise hidden by noise, and we show that
the stacked spectrum is representative of an average member of the set. The
flux limited, Ly signal-to-noise ratio restricted stack of 50K HETDEX
LAEs shows the ensemble biweight ``average" LAE to be a blue (UV
continuum slope and E(B-V) ), moderately bright
(M) star forming galaxy with strong Ly
emission (log 42.8 and (Ly)
114\AA), and potentially significant leakage of ionizing radiation. The
restframe UV light is dominated by a young, metal poor stellar population with
an average age 5-15 Myr and metallicity of 0.2-0.3 Z.Comment: 17 pages, 11 figures, 2 data files (ApJ Accepted
HETDEX Public Source Catalog 1: 220K Sources Including Over 50K Lyman Alpha Emitters from an Untargeted Wide-area Spectroscopic Survey
We present the first publicly released catalog of sources obtained from the
Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral
field spectroscopic survey designed to measure the Hubble expansion parameter
and angular diameter distance at 1.88<z<3.52 by using the spatial distribution
of more than a million Ly-alpha-emitting galaxies over a total target area of
540 deg^2. The catalog comes from contiguous fiber spectra coverage of 25 deg^2
of sky from January 2017 through June 2020, where object detection is performed
through two complementary detection methods: one designed to search for line
emission and the other a search for continuum emission. The HETDEX public
release catalog is dominated by emission-line galaxies and includes 51,863
Ly{\alpha}-emitting galaxy (LAE) identifications and 123,891 OII-emitting
galaxies at z<0.5. Also included in the catalog are 37,916 stars, 5274
low-redshift (z<0.5) galaxies without emission lines, and 4976 active galactic
nuclei. The catalog provides sky coordinates, redshifts, line identifications,
classification information, line fluxes, OII and Ly-alpha line luminosities
where applicable, and spectra for all identified sources processed by the
HETDEX detection pipeline. Extensive testing demonstrates that HETDEX redshifts
agree to within deltaz < 0.02, 96.1% of the time to those in external
spectroscopic catalogs. We measure the photometric counterpart fraction in deep
ancillary Hyper Suprime-Cam imaging and find that only 55.5% of the LAE sample
has an r-band continuum counterpart down to a limiting magnitude of r~26.2 mag
(AB) indicating that an LAE search of similar sensitivity with photometric
pre-selection would miss nearly half of the HETDEX LAE catalog sample. Data
access and details about the catalog can be found online at http://hetdex.org/.Comment: 38 pages, 20 figures. Data access and details about the catalog can
be found online at http://hetdex.org/. A copy of the catalogs presented in
this work (Version 3.2) is available to download at Zenodo
doi:10.5281/zenodo.744850
The Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) Survey Design, Reductions, and Detections
We describe the survey design, calibration, commissioning, and emission-line detection algorithms for the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX). The goal of HETDEX is to measure the redshifts of over a million Lyα emitting galaxies between 1.88 < z < 3.52, in a 540 deg2 area encompassing a comoving volume of 10.9 Gpc3. No preselection of targets is involved; instead the HETDEX measurements are accomplished via a spectroscopic survey using a suite of wide-field integral field units distributed over the focal plane of the telescope. This survey measures the Hubble expansion parameter and angular diameter distance, with a final expected accuracy of better than 1%. We detail the project’s observational strategy, reduction pipeline, source detection, and catalog generation, and present initial results for science verification in the Cosmological Evolution Survey, Extended Groth Strip, and Great Observatories Origins Deep Survey North fields. We demonstrate that our data reach the required specifications in throughput, astrometric accuracy, flux limit, and object detection, with the end products being a catalog of emission-line sources, their object classifications, and flux-calibrated spectra
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HETDEX Public Source Catalog 1: 220 K Sources Including Over 50 K Lyα Emitters from an Untargeted Wide-area Spectroscopic Survey* * Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.
We present the first publicly released catalog of sources obtained from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral field spectroscopic survey designed to measure the Hubble expansion parameter and angular diameter distance at 1.88 < z < 3.52 by using the spatial distribution of more than a million Lyα-emitting galaxies over a total target area of 540 deg2. The catalog comes from contiguous fiber spectra coverage of 25 deg2 of sky from 2017 January through 2020 June, where object detection is performed through two complementary detection methods: one designed to search for line emission and the other a search for continuum emission. The HETDEX public release catalog is dominated by emission-line galaxies and includes 51,863 Lyα-emitting galaxy (LAE) identifications and 123,891 [O ii]-emitting galaxies at z < 0.5. Also included in the catalog are 37,916 stars, 5274 low-redshift (z < 0.5) galaxies without emission lines, and 4976 active galactic nuclei. The catalog provides sky coordinates, redshifts, line identifications, classification information, line fluxes, [O ii] and Lyα line luminosities where applicable, and spectra for all identified sources processed by the HETDEX detection pipeline. Extensive testing demonstrates that HETDEX redshifts agree to within Δz < 0.02, 96.1% of the time to those in external spectroscopic catalogs. We measure the photometric counterpart fraction in deep ancillary Hyper Suprime-Cam imaging and find that only 55.5% of the LAE sample has an r-band continuum counterpart down to a limiting magnitude of r ∼ 26.2 mag (AB) indicating that an LAE search of similar sensitivity to HETDEX with photometric preselection would miss nearly half of the HETDEX LAE catalog sample. Data access and details about the catalog can be found online at http://hetdex.org/. A copy of the catalogs presented in this work (Version 3.2) is available to download at Zenodo doi:10.5281/zenodo.7448504