Veritas observations of day-scale flaring of M 87 in 2010 April

VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 ± 0.16) × 10-11 cm-2 s-1 at energies above 350GeV. In 2010 April, VERITAS d...

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Detalles Bibliográficos
Autores principales: Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S.M., Buckley, J.H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M.P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J.P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C.M., Humensky, T.B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M.J., Lebohec, S., Madhavan, A.S., Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nũez, P.D., Ong, R.A., Orr, M., Otte, A.N., Park, N., Perkins, J.S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L.C., Reynolds, P.T., Roache, E., Rose, H.J., Ruppel, J., Saxon, D.B., Schroedter, M., Sembroski, G.H., Entürk, G.D., Skole, C., Staszak, D., Teić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V.V., Vincent, S., Vivier, M., Wakely, S.P., Ward, J.E., Weekes, T.C., Weinstein, A., Weisgarber, T., Williams, D.A., Zitzer, B.
Formato: JOUR
Materias:
gamma rays: galaxies
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_0004637X_v746_n2_p_Aliu
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
Descripción
Sumario:VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M 87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 ± 0.16) × 10-11 cm-2 s-1 at energies above 350GeV. In 2010 April, VERITAS detected a flare from M 87 with peak flux of (2.71 ± 0.68) × 10-11 cm-2 s-1 for E > 350GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good-quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90+0.22 -0.15days. The shortest detected exponential rise time is three times as long, at 2.87 +1.65 -0.99days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 ± 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M 87 and the constraints they provide on the physical size of the emitting region. © 2012. The American Astronomical Society. All rights reserved.

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