Revisiting EBL Constraints from Gamma-Ray Observations: A Critical Assessment and Methodological Improvements
Abstract
The extragalactic background light (EBL), ranging from the infrared to the ultraviolet bands, is the second most intense photon field in the universe, surpassed only by the cosmic microwave background (CMB). It is primarily generated by starlight in galaxies, either directly or through absorption by dust and re-emission at longer wavelengths. Very high energy (VHE, E > 100GeV) photons can be absorbed via γγ interactions with the EBL during their propagation across cosmological distances, providing an indirect method to probe the EBL by studying its impact on the energy spectra of distant VHE sources. This paper examines the robustness of EBL constraints derived from gamma-ray data, critically assessing the assumptions made in previous studies about the intrinsic source spectra, the uncertainties of the observations and the validity of the analysis tools. We find that earlier studies likely underestimated the uncertainties in the EBL intensity constraints, underscoring the need to account for systematic uncertainties comprehensively. By employing a Monte Carlo (MC) simulation and a plausible model for unknown systematic errors, we compute more realistic uncertainties. Additionally, we discuss possible alternatives to set EBL constraints, relaxing the assumptions on the intrinsic spectra of gamma-ray sources, with the goal of achieving more robust constraints.
Versions
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BibTeX
@misc{abe2026revisiting,
title = {{Revisiting EBL Constraints from Gamma-Ray Observations: A Critical Assessment and Methodological Improvements}},
author = {K. Abe and S. Abe and J. Abhir and A. Abhishek and V. A. Acciari and A. Aguasca-Cabot and I. Agudo and I. Albanese and T. Aniello and S. Ansoldi and A. Arbet Engels and C. Arcaro and T. T. H. Arnesen and A. Babić and C. Bakshi and U. Barres de Almeida and J. A. Barrio and I. Batković and J. Baxter and J. Becerra González and W. Bednarek and E. Bernardini and J. Bernete and A. Berti and J. Besenrieder and C. Bigongiari and A. Biland and O. Blanch and G. Bonnoli and Ž. Bošnjak and E. Bronzini and I. Burelli and A. Campoy-Ordaz and A. Carosi and R. Carosi and M. Carretero-Castrillo and A. J. Castro-Tirado and D. Cerasole and G. Ceribella and A. Cerviño and Y. Chai and G. Chon and A. Cifuentes Santos and J. L. Contreras and J. Cortina and S. Covino and G. D'Amico and P. Da Vela and F. Dazzi and A. De Angelis and B. De Lotto and M. Delfino and J. Delgado and C. Delgado Mendez and F. Di Pierro and R. Di Tria and L. Di Venere and A. Dinesh and D. Dominis Prester and A. Donini},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08246},
eprint = {2609.08246},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08246},
}
RIS
TY - UNPB
TI - Revisiting EBL Constraints from Gamma-Ray Observations: A Critical Assessment and Methodological Improvements
AU - K. Abe
AU - S. Abe
AU - J. Abhir
AU - A. Abhishek
AU - V. A. Acciari
AU - A. Aguasca-Cabot
AU - I. Agudo
AU - I. Albanese
AU - T. Aniello
AU - S. Ansoldi
AU - A. Arbet Engels
AU - C. Arcaro
AU - T. T. H. Arnesen
AU - A. Babić
AU - C. Bakshi
AU - U. Barres de Almeida
AU - J. A. Barrio
AU - I. Batković
AU - J. Baxter
AU - J. Becerra González
AU - W. Bednarek
AU - E. Bernardini
AU - J. Bernete
AU - A. Berti
AU - J. Besenrieder
AU - C. Bigongiari
AU - A. Biland
AU - O. Blanch
AU - G. Bonnoli
AU - Ž. Bošnjak
AU - E. Bronzini
AU - I. Burelli
AU - A. Campoy-Ordaz
AU - A. Carosi
AU - R. Carosi
AU - M. Carretero-Castrillo
AU - A. J. Castro-Tirado
AU - D. Cerasole
AU - G. Ceribella
AU - A. Cerviño
AU - Y. Chai
AU - G. Chon
AU - A. Cifuentes Santos
AU - J. L. Contreras
AU - J. Cortina
AU - S. Covino
AU - G. D'Amico
AU - P. Da Vela
AU - F. Dazzi
AU - A. De Angelis
AU - B. De Lotto
AU - M. Delfino
AU - J. Delgado
AU - C. Delgado Mendez
AU - F. Di Pierro
AU - R. Di Tria
AU - L. Di Venere
AU - A. Dinesh
AU - D. Dominis Prester
AU - A. Donini
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08246
UR - https://arxiv.org/abs/2609.08246
AB - The extragalactic background light (EBL), ranging from the infrared to the ultraviolet bands, is the second most intense photon field in the universe, surpassed only by the cosmic microwave background (CMB). It is primarily generated by starlight in galaxies, either directly or through absorption by dust and re-emission at longer wavelengths. Very high energy (VHE, E > 100GeV) photons can be absorbed via γγ interactions with the EBL during their propagation across cosmological distances, providing an indirect method to probe the EBL by studying its impact on the energy spectra of distant VHE sources. This paper examines the robustness of EBL constraints derived from gamma-ray data, critically assessing the assumptions made in previous studies about the intrinsic source spectra, the uncertainties of the observations and the validity of the analysis tools. We find that earlier studies likely underestimated the uncertainties in the EBL intensity constraints, underscoring the need to account for systematic uncertainties comprehensively. By employing a Monte Carlo (MC) simulation and a plausible model for unknown systematic errors, we compute more realistic uncertainties. Additionally, we discuss possible alternatives to set EBL constraints, relaxing the assumptions on the intrinsic spectra of gamma-ray sources, with the goal of achieving more robust constraints.
ER -