First HAWC observations of the Sun constrain steady TeV gamma-ray emission

Journal Article · Mon Dec 17 00:00:00 EST 2018 · Physical Review D

DOI:https://doi.org/10.1103/PhysRevD.98.123011· OSTI ID:1511615

Albert, A.; Alfaro, R.; Alvarez, C.; Arceo, R.; Arteaga-Velázquez, J. C.; Avila Rojas, D.; Ayala Solares, H. A.; Belmont-Moreno, E.; BenZvi, S. Y.; Brisbois, C.; Caballero-Mora, K. S.; Capistrán, T.; Carramiñana, A.; Casanova, S.; Castillo, M.; Cotzomi, J.; Coutiño de León, S.; De León, C.; De la Fuente, E.; Dichiara, S. ; Dingus, B. L.; DuVernois, M. A.; Díaz-Vélez, J. C.; Engel, K.; Enríquez-Rivera, O.; Espinoza, C.; Fleischhack, H.; Fraija, N.; García-González, J. A.; Garfias, F.; González, M. M.; Goodman, J. A.; Hampel-Arias, Z.; Harding, J. P.; Hernandez, S.; Hona, B.; Hueyotl-Zahuantitla, F.; Hüntemeyer, P.; Iriarte, A.; Jardin-Blicq, A.; Joshi, V.; Kaufmann, S.; León Vargas, H.; Luis-Raya, G.; Lundeen, J.; López-Coto, R.; Malone, K.; Marinelli, S. S.; Martinez, O.; Martinez-Castellanos, I.; Martínez-Castro, J.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nayerhoda, A.; Nellen, L.; Newbold, M.; Nisa, M. U.; Noriega-Papaqui, R.; Pretz, J.; Pérez-Pérez, E. G.; Ren, Z.; Rho, C. D.; Rivière, C.; Rosa-González, D.; Rosenberg, M.; Ruiz-Velasco, E.; Salazar, H.; Salesa Greus, F.; Sandoval, A.; Schneider, M.; Schoorlemmer, H.; Seglar Arroyo, M.; Sinnis, G.; Smith, A. J.; Springer, R. W.; Surajbali, P.; Taboada, I.; Tibolla, O.; Tollefson, K.; Torres, I.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wisher, I. G.; Wood, J.; Yapici, T.; Zepeda, A.; Zhou, H.; Álvarez, J. D.; Beacom, J. F.; Leane, R. K.; Linden, T.; Ng, K. C. Y.; Peter, A. H. G.; Zhou, B.

Steady gamma-ray emission up to at least 200 GeV has been detected from the solar disk in the Fermi-LAT data, with the brightest, hardest emission occurring during solar minimum. The likely cause is hadronic cosmic rays undergoing collisions in the Sun’s atmosphere after being redirected from ingoing to outgoing in magnetic fields, though the exact mechanism is not understood. An important new test of the gamma-ray production mechanism will follow from observations at higher energies. Only the High Altitude Water Cherenkov (HAWC) Observatory has the required sensitivity to effectively probe the Sun in the TeV range. Here, using 3 years of HAWC data from November 2014 to December 2017, just prior to the solar minimum, we search for 1–100 TeV gamma rays from the solar disk. No evidence of a signal is observed, and we set strong upper limits on the flux at a few 10-¹² TeV^-1 cm^-2 s^-1 at 1 TeV. Our limit, which is the most constraining result on TeV gamma rays from the Sun, is ~ 10 % of the theoretical maximum flux (based on a model where all incoming cosmic rays produce outgoing photons), which in turn is comparable to the Fermi-LAT data near 100 GeV. The prospects for a first TeV detection of the Sun by HAWC are especially high during the solar minimum, which began in early 2018.

• Research Organization: Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC). High Energy Physics (HEP) (SC-25); USDOE
• Contributing Organization: HAWC Collaboration
• Grant/Contract Number: 89233218CNA000001; SC00012567; SC0013999
• OSTI ID: 1511615
• Alternate ID(s): OSTI ID: 1487176
• Report Number(s): LA-UR-18-29831; PRVDAQ
• Journal Information: Physical Review D, Vol. 98, Issue 12; ISSN 2470-0010
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
79 ASTRONOMY AND ASTROPHYSICS
Atomic
Nuclear and Particle Physics
Astronomy and Astrophysics