Using Lyman Alpha Absorption to Measure the Intensity and Variability of $z \sim 2.4$ Ultraviolet Background Light
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| Autores principales: | , , , , , , , , , , , , , |
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| Formato: | Preprint |
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2025
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| author | Weiss, Laurel H. Gebhardt, Karl Davis, Dustin Cooper, Erin Mentuch Niemeyer, Maja Lujan Qezlou, Mahdi Khanlari, Mahan Mirza Ciardullo, Robin Farrow, Daniel Gawiser, Eric Gazagnes, Simon Gronwall, Caryl Hill, Gary J. Schneider, Donald P. |
| author_facet | Weiss, Laurel H. Gebhardt, Karl Davis, Dustin Cooper, Erin Mentuch Niemeyer, Maja Lujan Qezlou, Mahdi Khanlari, Mahan Mirza Ciardullo, Robin Farrow, Daniel Gawiser, Eric Gazagnes, Simon Gronwall, Caryl Hill, Gary J. Schneider, Donald P. |
| contents | We present measurements of $z \sim 2.4$ ultraviolet background light using Lya absorption from galaxies at $z \sim 2-3$ 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 ultraviolet light from background galaxies is absorbed by \ion{H}{1} within the halo of a foreground galaxy, in a configuration similar to damped Lya systems. 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 over-subtracted is representative of the $z \sim 2.4$ UV contribution to the overall extragalactic background light (EBL) at Lya. Using this method, we determine an average intensity (in $νJ_ν$ units) of $12.9 \pm 3.7$ nW m$^{-2}$ sr$^{-1}$ at a median observed wavelength of 4134 angstroms, or a rest-frame UV background intensity of $508 \pm 145$ nW m$^{-2}$ sr$^{-1}$ at $z\sim2.4$. 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_13253 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Using Lyman Alpha Absorption to Measure the Intensity and Variability of $z \sim 2.4$ Ultraviolet Background Light Weiss, Laurel H. Gebhardt, Karl Davis, Dustin Cooper, Erin Mentuch Niemeyer, Maja Lujan Qezlou, Mahdi Khanlari, Mahan Mirza Ciardullo, Robin Farrow, Daniel Gawiser, Eric Gazagnes, Simon Gronwall, Caryl Hill, Gary J. Schneider, Donald P. Astrophysics of Galaxies We present measurements of $z \sim 2.4$ ultraviolet background light using Lya absorption from galaxies at $z \sim 2-3$ 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 ultraviolet light from background galaxies is absorbed by \ion{H}{1} within the halo of a foreground galaxy, in a configuration similar to damped Lya systems. 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 over-subtracted is representative of the $z \sim 2.4$ UV contribution to the overall extragalactic background light (EBL) at Lya. Using this method, we determine an average intensity (in $νJ_ν$ units) of $12.9 \pm 3.7$ nW m$^{-2}$ sr$^{-1}$ at a median observed wavelength of 4134 angstroms, or a rest-frame UV background intensity of $508 \pm 145$ nW m$^{-2}$ sr$^{-1}$ at $z\sim2.4$. 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. |
| title | Using Lyman Alpha Absorption to Measure the Intensity and Variability of $z \sim 2.4$ Ultraviolet Background Light |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2504.13253 |