https://doi.org/10.1051/epjconf/202531905005
Do the LHAASO Galactic diffuse emission data require a contribution from unresolved sources?
1 Norwegian University of Science and Technology, Department of Physics, NO-7491 Trondheim, Norway
2 INAF Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125, Firenze, Italy
3 Astrofísica de Andalucía, CSIC, 18080 Granada, Spain
4 INFN, Laboratori Nazionali del Gran Sasso, 67100 Assergi (AQ), Italy
5 University of L’Aquila, Physics and Chemistry Department, 67100 L’Aquila, Italy
* e-mail: vittoria.vecchiotti@ntnu.no
Published online: 6 March 2025
The Large High-Altitude Air Shower Observatory (LHAASO) collaboration has recently measured the ultra-high energy gamma-ray diffuse emission (10 − 103 TeV) after masking the contribution of known sources. The observed signal appears to be 2 − 3 times higher than expected from the hadronic interactions of diffuse cosmic rays with the interstellar medium, potentially suggesting a contribution from unresolved sources. However, estimates of the diffuse emission are affected by large uncertainties. In this work, we calculate the hadronic gamma-ray diffuse emission, accounting for uncertainties in the gas content of the Galactic disk, the energy and spatial distribution of cosmic rays, and the hadronic interaction cross-section. We show that the LHAASO data above ∼ 30 TeV are consistent with this model, not requiring (nor probing) the existence of any further contribution due to unresolved sources or cosmic ray spectral variations in the inner Galaxy.
© The Authors, published by EDP Sciences, 2025
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
