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This content will become publicly available on April 8, 2026

Title: Using Ly α Absorption to Measure the Intensity and Variability of z  ∼ 2.4 Ultraviolet Background Light
Abstract We present measurements ofz ∼ 2.4 ultraviolet (UV) background light using Lyαabsorption from galaxies atz ∼ 2–3 in the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX) database. Thanks to the wide area of this survey, we also measure the variability of this light across the sky. The data suggest an asymmetric geometry where integrated UV light from background galaxies is absorbed by Hiwithin the halo of a foreground galaxy, in a configuration similar to damped Lyαsystems. Using stacking analyses of over 400,000 HETDEX LAE spectra, we argue that this background absorption is detectable in our data. We also argue that the absorption signal becomes negative due to HETDEX’s sky-subtraction procedure. The amount that the absorption is oversubtracted is representative of thez ∼ 2.4 UV contribution to the overall extragalactic background light (EBL) at Lyα. Using this method, we determine an average intensity (inνJνunits) of 12.9 ± 3.7 nW m−2sr−1at a median observed wavelength of 4134 Å, or a rest-frame UV background intensity of 508 ± 145 nW m−2sr−1atz ∼ 2.4. We find that this flux varies significantly depending on the density of galaxies in the field of observation. Our estimates are consistent with direct measurements of the overall EBL.  more » « less
Award ID(s):
2408358
PAR ID:
10638951
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
IOP
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
983
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
72
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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