Observation of Anisotropy of TeV Cosmic Rays with Two Years of HAWC

A. U. Abeysekara, R. Alfaro, C. Alvarez, J. D. Alvarez, R. Arceo, J. C. Arteaga-Velázquez, D. Avila Rojas, H. A.Ayala Solares, A. Becerril, E. Belmont-Moreno, S. Y. Benzvi, A. Bernal, J. Braun, K. S. Caballero-Mora, T. Capistrán, A. Carraminana, S. Casanova, M. Castillo, U. Cotti, J. CotzomiC. De León, E. De La Fuente, R. Diaz Hernandez, S. Dichiara, B. L. Dingus, M. A. Duvernois, J. C. Diaz-Vélez, K. Engel, D. W. Fiorino, N. Fraija, J. A. Garcia-González, F. Garfias, A. González Munoz, M. M. González, J. A. Goodman, Z. Hampel-Arias, J. P. Harding, S. Hernandez, B. Hona, F. Hueyotl-Zahuantitla, C. M. Hui, P. Hüntemeyer, A. Iriarte, A. Jardin-Blicq, V. Joshi, S. Kaufmann, A. Lara, R. J. Lauer, W. H. Lee, H. León Vargas, A. L. Longinotti, G. Luis-Raya, R. Luna-Garcia, D. López-Cámara, R. López-Coto, D. López-Cámara, R. López-Coto, K. Malone, S. S. Marinelli, O. Martinez, I. Martinez-Castellanos, J. Martinez-Castro, H. Martinez-Huerta, J. A. Matthews, P. Miranda-Romagnoli, E. Moreno, M. Mostafá, A. Nayerhoda, L. Nellen, M. Newbold, M. U. Nisa, R. Noriega-Papaqui, R. Pelayo, J. Pretz, E. G. Pérez-Pérez, Z. Ren, C. D. Rho, C. Riviere, D. Rosa-González, M. Rosenberg, E. Ruiz-Velasco, F. Salesa Greus, A. Sandoval, M. Schneider, H. Schoorlemmer, M. Seglar Arroyo, G. Sinnis, A. J. Smith, R. W. Springer, P. Surajbali, I. Taboada, O. Tibolla, K. Tollefson, I. Torres, G. Vianello, L. Villasenor, T. Weisgarber, F. Werner, S. Westerhoff, J. Wood, T. Yapici, A. Zepeda, H. Zhou

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After two years of operation, the High-Altitude Water Cherenkov (HAWC) Observatory has analyzed the TeV cosmic-ray sky over an energy range between 2.0 and 72.8 TeV. Like other detectors in the northern and southern hemispheres, HAWC observes an energy-dependent anisotropy in the arrival direction distribution of cosmic rays. This anisotropy is dominated by a dipole moment with phase in R.A. α ≈ 40° and amplitude that slowly rises in relative intensity from 8 ×10-4 at 2 TeV to 14 ×10-4 around 30 TeV, above which the dipole decreases in strength. A significant large-scale (>60° in angular extent) signal is also observed in the quadrupole and octupole moments, and significant small-scale features are also present, with locations and shapes consistent with previous observations. Compared to previous measurements in this energy range, the HAWC cosmic-ray sky maps improve on the energy resolution and fit precision of the anisotropy. These data can be used in an effort to better constrain local cosmic-ray accelerators and the intervening magnetic fields.

Original languageEnglish (US)
Article number57
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 20 2018

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Abeysekara, A. U., Alfaro, R., Alvarez, C., Alvarez, J. D., Arceo, R., Arteaga-Velázquez, J. C., Rojas, D. A., Solares, H. A. A., Becerril, A., Belmont-Moreno, E., Benzvi, S. Y., Bernal, A., Braun, J., Caballero-Mora, K. S., Capistrán, T., Carraminana, A., Casanova, S., Castillo, M., Cotti, U., ... Zhou, H. (2018). Observation of Anisotropy of TeV Cosmic Rays with Two Years of HAWC. Astrophysical Journal, 865(1), [57]. https://doi.org/10.3847/1538-4357/aad90c