{"paper":{"title":"HAWC, VERITAS, Fermi-LAT and XMM-Newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO J2108+5157","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"A. Bernal, A. Carrami\\~nana, A. Furniss, A. Gonzalez Mu\\~noz, A. Iriarte, A. J. Chromey, A. J. Smith, A. K. Talluri, A. Lara, A. L. Longinotti, A. Nayerhoda, A. Sandoval, C. Alvarez, C. de Le\\'on, C. D. Rho, C. E. Hinrichs, C. Espinoza, Charles J. Hailey, D. Avila Rojas, D. A. Williams, D. Depaoli, D. Huang, D. Kieda, D. Ribeiro, D. Rosa-Gonz\\'alez, D. Tak, E. Belmont-Moreno, E. De la Fuente, E.G. P\\'erez-P\\'erez, E. Moreno, E. Ponce, E. Pueschel, E. Roache, E. Varela, F. Garfias, F. Hueyotl-Zahuantitla, F. Ure\\~na-Mena, G. H. Sembroski, G. Luis-Raya, G. Maier, H. Le\\'on Vargas, H. Salazar, H. Wu, H. Zhou, I. Herzog, I. J. Watson, I. Sadeh, I. Torres, J.A. Garc\\'ia-Gonz\\'alez, J.A. Goodman, J. A. Matthews, J. A. Morales-Soto, J. C. Arteaga-Vel'azquez, J. Cotzomi, J. Foote, J. H. Buckley, J. Holder, J. L. Christiansen, J. Lee, J. Mart\\'inez-Castro, J. P. Harding, J. Quinn, J. Serna-Franco, J. Valverde, J. V. Tucci, J. Woo The HAWC collaboration: R. Alfaro, K. Engel, K. L. Fan, K. Malone, K. Ragan, K. S. Caballero-Mora, K. Tollefson, L. Fortson, L. Nellen, L. Saha, L. Villase\\~nor, M. A. DuVernois, M. Araya, M. Escobar Godoy, M. J. Lang, M. J. Millard, M. Kertzman, M. Kherlakian, M. Lundy, M. Martin The XMM-Newton collaboration: Kaya Mori, M.M. Gonz\\'alez, M. Mostaf\\'a, M. Najafi, M. Pohl, M. Roth, M. Schneider, N. Di Lalla, N. Fraija, N. Korzoun, N. Omodei, O. Hervet, O. Martinez, O. Tibolla, P. Bangale, P. Desiati, P. H\\\"untemeyer, P. Kaaret, P. L. Rabinowitz, P. Miranda-Romagnoli, P. Moriarty, P. T. Reynolds, Q. Feng, R. A. Ong, R. Babu, R. Diaz Hernandez, R. Mukherjee, R. Shang, R. Torres-Escobedo, R. Turner, R. W. Springer, Samar Safi-Harb, S. Casanova, S. Feldman, S. Fraija, S. Groetsch, S. Hern\\'andez-Cadena, Shuo Zhang, S. Kaufmann, S. Kumar, S. L. Wong, S. Yu, S. Yun-C\\'arcamo, T. B. Humensky, T. Ergin, The VERITAS collaboration: C. B. Adams, T. K. Kleiner, U. Cotti, W. Benbow, W. Hanlon, W. Jin, W. Ning, X. Wang, Y. Chen, Y. Son, Z. Hughes, Z. Wang","submitted_at":"2025-08-03T22:07:29Z","abstract_excerpt":"We report observations of the ultra-high-energy gamma-ray source LHAASO J2108$+$5157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected $\\sim$ 40 hours of data that we used to set ULs to the emission above 200 GeV. The HAWC data, collected over $\\sim 2400$ days, reveal emission between 3 and 146 TeV, with a significance of $7.5~\\sigma$, favoring an extended source model. The best-fit spectrum measured by HAWC is characterized by a simple power-law with a spectral index of $2.45\\pm0.11_{stat}$. Fermi-LAT analysis finds a point source with a very soft spectrum in the LHAA"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2508.01934","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2508.01934/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}