The TeV Sun Rises: Discovery of Gamma rays from the Quiescent Sun with HAWC

• Published in: arXiv.org 2023-07
• Main Authors: Albert, A, Alfaro, R, Alvarez, C, Arteaga-Velazquez, J C, D Avila Rojas, Ayala Solares, H A, Babu, R, Belmont-Moreno, E, Brisbois, C, Caballero-Mora, K S, Capistran, T, Carraminana, A, Casanova, S, Chaparro-Amaro, O, Cotti, U, Cotzomi, J, S Coutino de Leon, De la Fuente, E, R Diaz Hernandez, Dingus, B L, DuVernois, M A, Durocher, M, Diaz-Velez, J C, Ellsworth, R W, Engel, K, Espinoza, C, Fan, K L, Fang, K, M Fernandez Alonso, Fleischhack, H, Fraija, N, Garcia-Gonzalez, J A, Garfia, F, Gonzalez, M M, Goodman, J A, Harding, J P, Hernandez, S, Hinton, J, Huang, D, Hueyotl-Zahuantitla, F, Huntemeyer, P, Iriarte, A, Joshi, V, Kaufmann, S, Lee, J, Linnemann, J T, Longinotti, A L, Luis-Raya, G, Malone, K, Martinez, O, Martinez-Castro, J, Matthews, J A, Miranda-Romagnoli, P, Morales-Soto, J A, Moreno, E, Mostafa, M, Nayerhoda, A, Nellen, L, Nisa, M U, Noriega-Papaqui, R, Olivera-Nieto, L, Omodei, N, Y Pérez Araujo, Perez-Perez, E G, Rho, C D, Rosa-Gonzalez, D, Ruiz-Velasco, E, Salazar, H, Salazar-Gallegos, D, Sandoval, A, Schneider, M, Serna-Franco, J, Smith, A J, Son, Y, Springer, R W, Tibolla, O, Tollefson, K, Torres, I, Torres-Escobedo, R, Turner, R, Urena-Mena, F, Wang, X, Watson, I J, Willox, E, Yun-Cárcamo, S, Zhou, H, de León, C, Beacom, J F, Linden, T, Ng, K C Y, Peter, A H G, Zhou, B
• Format: Article
• Language: English
• Subjects: Atmospheric models; Emission; Galactic cosmic rays; Gamma rays; High altitude; Solar activity; Solar atmosphere; Solar magnetic field
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2212.00815

We report the first detection of a TeV gamma-ray flux from the solar disk (6.3\(\sigma\)), based on 6.1 years of data from the High Altitude Water Cherenkov (HAWC) observatory. The 0.5--2.6 TeV spectrum is well fit by a power law, dN/dE = \(A (E/1 \text{ TeV})^{-\gamma}\), with \(A = (1.6 \pm 0.3) \times 10^{-12}\) TeV\(^{-1}\) cm\(^{-2}\) s\(^{-1}\) and \(\gamma = -3.62 \pm 0.14\). The flux shows a strong indication of anticorrelation with solar activity. These results extend the bright, hard GeV emission from the disk observed with Fermi-LAT, seemingly due to hadronic Galactic cosmic rays showering on nuclei in the solar atmosphere. However, current theoretical models are unable to explain the details of how solar magnetic fields shape these interactions. HAWC's TeV detection thus deepens the mysteries of the solar-disk emission.