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Main Authors: Banerjee, Anuvab, Finke, Justin D., Ajello, Marco, Domínguez, Alberto, Desai, Abhishek, Baxter, Joshua, Hartmann, Dieter, Paliya, Vaidehi S.
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2604.09139
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author Banerjee, Anuvab
Finke, Justin D.
Ajello, Marco
Domínguez, Alberto
Desai, Abhishek
Baxter, Joshua
Hartmann, Dieter
Paliya, Vaidehi S.
author_facet Banerjee, Anuvab
Finke, Justin D.
Ajello, Marco
Domínguez, Alberto
Desai, Abhishek
Baxter, Joshua
Hartmann, Dieter
Paliya, Vaidehi S.
contents The extragalactic background Light (EBL) from ultraviolet to infrared comprises the emission from all stars, galaxies, and actively accreting black holes in the observable Universe. A precise measurement of the EBL is critically important to probe models of star formation and galaxy evolution. The EBL can be measured via the absorption imprint left on the spectra of gamma-ray blazars. In this work, we rely on 15 years of {\it Fermi}-LAT data and 1576 blazars to measure the EBL optical depth in the $0<z<4.3$ range. We detect the EBL attenuation with $\sim23σ$ significance and measure the optical depth in 19 redshift bins, extending the coverage and improving on our previous results. This allows us to reconstruct the EBL evolution and find general consistency with recent EBL models. These results represent the most precise determination of the EBL with GeV $γ$ rays to date.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09139
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A New Measurement of the Extragalactic Background Light using 15\,yr of {\it Fermi}-Large Area Telescope Data
Banerjee, Anuvab
Finke, Justin D.
Ajello, Marco
Domínguez, Alberto
Desai, Abhishek
Baxter, Joshua
Hartmann, Dieter
Paliya, Vaidehi S.
High Energy Astrophysical Phenomena
The extragalactic background Light (EBL) from ultraviolet to infrared comprises the emission from all stars, galaxies, and actively accreting black holes in the observable Universe. A precise measurement of the EBL is critically important to probe models of star formation and galaxy evolution. The EBL can be measured via the absorption imprint left on the spectra of gamma-ray blazars. In this work, we rely on 15 years of {\it Fermi}-LAT data and 1576 blazars to measure the EBL optical depth in the $0<z<4.3$ range. We detect the EBL attenuation with $\sim23σ$ significance and measure the optical depth in 19 redshift bins, extending the coverage and improving on our previous results. This allows us to reconstruct the EBL evolution and find general consistency with recent EBL models. These results represent the most precise determination of the EBL with GeV $γ$ rays to date.
title A New Measurement of the Extragalactic Background Light using 15\,yr of {\it Fermi}-Large Area Telescope Data
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2604.09139