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Astrophysics and Astronomy | External Galaxies | Stars, Interstellar Medium and the Galaxy
1.3 PHYSICAL SCIENCES
We report the detection of very high energy γ-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z = 0.102) by VERITAS. The source was observed between 2008 January and April. A strong outburst of γ-ray emission was measured in the middle of March, lasting for only 4 days. The energy spectrum measured during the two highest flare nights is fit by a power law and is found to be very steep, with a differential photon spectral index of Γ = 3.81 ± 0.35stat± 0.34syst. The integral photon flux above 200 GeV during those two nights corresponds to roughly 9% of the flux from the Crab Nebula. Quasi-simultaneous Swift observations at X-ray energies were triggered by the VERITAS observations. The spectral energy distribution of the flare data can be described by synchrotron self-Compton (SSC) or external Compton (EC) leptonic jet models.
Acciari, V.A., Aliu, E., Beilicke, M., Benbow, W., Böttcher, M., Bradbury, S.M., Buckley, J.H., Bugaev, V., Butt, Y., Celik, O., Cesarini, A., Ciupik, L., Chow, Y.C.K., Cogan, P., Colin, P., Cui, W., Daniel, M.K., Ergin, T., Falcone, A.D., Fegan, S.J., Finley, J.P., Finnegan, G., Fortin, P., Fortson, L.F., Furniss, A., Gall, D., Gillanders, G.H., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Hays, E., Holder, J., Horan, D., Hui, C.M., Humensky, T.B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D.B., Konopelko, A., Krawczynski, H., Krennrich, F., Lang, M.J., LeBohec, S., Lee, K., Maier, G., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nagai, T., Niemiec, J., Ong, R.A., Pandel, D., Perkins, J.S., Petry, D., Pohl, M., Quinn, J., Ragan, K., Reyes, L.C., Reynolds, P.T., Roache, E., Rose, H.J., Schroedter, M., Sembroski, G.H., Smith, A.W., Steele, D., Swordy, S.P., Toner, J.A., Vassiliev, V.V., Wagner, R., Wakely, S.P., Ward, J.E., Weekes, T.C., Weinstein, A., White, R.J., Williams, D.A., Wissel, S.A., Wood, M. and Zitzer, B. (2008). VERITAS Discovery of >200 GeV Gamma-Ray Emission from the Intermediate-Frequency-Peaked BL Lacertae Object W Comae. The Astrophysical Journal, 684(2), pp.L73–L77. Available at: https://iopscience.iop.org/article/10.1086/592244 [Accessed