Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC
Creators: name: Abeysekara, A. U.
name: Albert, A.
name: Alfaro, R.
name: Alvarez, C.
name: Álvarez, J. D.
name: Arceo, R.
name: Arteaga-Velázquez, J. C.
name: Rojas, D. Avila
name: Solares, H. A. Ayala
name: Barber, A. S.
name: Bautista-Elivar, N.
name: Gonzalez, J. Becerra
name: Becerril, A.
name: Belmont-Moreno, E.
name: BenZvi, S. Y.
name: Bernal, A.
name: Braun, J.
name: Brisbois, C.
name: Caballero-Mora, K. S.
name: Capistrán, T.
name: Carramiñana, A.
name: Casanova, S.
name: Castillo, M.
name: Cotti, U.
name: Cotzomi, J.
name: de León, S. Coutiño
name: De León, C.
name: De la Fuente, E.
name: Hernandez, R. Diaz
name: Dingus, B. L.
name: DuVernois, M. A.
name: Díaz-Vélez, J. C.
name: Ellsworth, R. W.
name: Engel, K.
name: Fiorino, D. W.
name: Fraija, N.
name: García-González, J. A.
name: Garfias, F.
name: Gerhardt, M.
name: Muñoz, A. González
name: González, M. M.
name: Goodman, J. A.
name: Hampel-Arias, Z.
name: Harding, J. P.
name: Hernandez, S.
name: Hernandez-Almada, A.
name: Hona, B.
name: Hui, C. M.
name: Hüntemeyer, P.
name: Iriarte, A.
name: Jardin-Blicq, A.
name: Joshi, V.
name: Kaufmann, S.
name: Kieda, D.
name: Lara, A.
name: Lauer, R. J.
name: Lee, W. H.
name: Lennarz, D.
name: Vargas, H. León
name: Linnemann, J. T.
name: Longinotti, A. L.
name: Raya, G. Luis
name: Luna-García, R.
name: López-Coto, R.
name: Malone, K.
name: Marinelli, S. S.
name: Martinez, O.
name: Martinez-Castellanos, I.
name: Martínez-Castro, J.
name: Matthews, J. A.
name: Miranda-Romagnoli, P.
name: Moreno, E.
name: Mostafá, M.
name: Nellen, L.
name: Newbold, M.
name: Nisa, M. U.
name: Noriega-Papaqui, R.
name: Pretz, J.
name: Pérez-Pérez, E. G.
name: Ren, Z.
name: Rho, C. D.
name: Rivière, C.
name: Rosa-González, D.
name: Rosenberg, M.
name: Ruiz-Velasco, E.
name: Greus, F. Salesa
name: Sandoval, A.
name: Schneider, M.
name: Schoorlemmer, H.
name: Sinnis, G.
name: Smith, A. J.
name: Springer, R. W.
name: Surajbali, P.
name: Taboada, I.
name: Tibolla, O.
name: Tollefson, K.
name: Torres, I.
name: Ukwatta, T. N.
name: Vianello, G.
name: Weisgarber, T.
name: Westerhoff, S.
name: Wisher, I. G.
name: Wood, J.
name: Yapici, T.
name: Younk, P. W.
name: Zepeda, A.
name: Zhou, H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We present results from daily monitoring of gamma rays in the energy range $\sim0.5$ to $\sim100$ TeV with the first 17 months of data from the High Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2 steradians and duty cycle of $&gt;95$% are unique features compared to other TeV observatories that allow us to observe every source that transits over HAWC for up to $\sim6$ hours each sidereal day. This regular sampling yields unprecedented light curves from unbiased measurements that are independent of seasons or weather conditions. For the Crab Nebula as a reference source we find no variability in the TeV band. Our main focus is the study of the TeV blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a power law index $Γ=2.21 \pm0.14_{\mathrm{stat}}\pm0.20_{\mathrm{sys}}$ and an exponential cut-off $E_0=5.4 \pm 1.1_{\mathrm{stat}}\pm 1.0_{\mathrm{sys}}$ TeV. For Mrk 501, we find an index $Γ=1.60\pm 0.30_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}}$ and exponential cut-off $E_0=5.7\pm 1.6_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}}$ TeV. The light curves for both sources show clear variability and a Bayesian analysis is applied to identify changes between flux states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab Nebula flux by a factor of approximately five. For Mrk 501, several transits show fluxes in excess of three times the Crab Nebula flux. In a comparison to lower energy gamma-ray and X-ray monitoring data with comparable sampling we cannot identify clear counterparts for the most significant flaring features observed by HAWC.
description: 18 pages, 10 figures, accepted for publication in The Astrophysical Journal