New Hard-TeV Extreme Blazars Detected with the MAGIC Telescopes*
V. A. Acciari, Stefano Ansoldi, L. A. Antonelli, A. Arbet Engels, Katsuaki Asano, Dominik Baack, A. Babić, B. Banerjee, U. Barres de Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, Lorenzo Bellizzi, E. Bernardini, A. Berti, Jürgen Besenrieder, W. Bhattacharyya, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, G. Busetto, R. Carosi, G. Ceribella, M. Cerruti, Yating Chai, A. Chilingaryan, S. Cikota, S. M. Colak, U. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, V. D’Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, Davide Depaoli, F. Di Pierro, L. Di Venere, E. Do Souto Espiñeira, D. Dominis Prester, Alice Donini, D. Dorner, M. Doro, D. Elsäesser, V. Fallah Ramazanı, Alicia Fattorini, G. Ferrara, D. Fidalgo, L. Foffano, M. V. Fonseca, L. Font, C. Fruck, Satoshi Fukami, R. J. Garcı́a López, M. Garczarczyk, Sargis Gasparyan, M. Gaug, N. Giglietto, F. Giordano, N. Godinović, D. Green, D. Guberman, D. Hadasch, A. Hahn, J. Herrera, John Hoang, Dario Hrupec, Moritz Hütten, Tomohiro Inada, Susumu Inoue, Kazuma Ishio, Y. Iwamura, L. Jouvin, D. Kerszberg, H. Kubo, J. Kushida, A. Lamastra, D. Lelas, F. Leone, E. Lindfors, S. Lombardi, F. Longo, Marcos López, R. López-Coto, A. López-Oramas, S. Loporchio, B. Machado de Oliveira Fraga, C. Maggio, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro
Abstract
Abstract Extreme high-frequency-peaked BL Lac objects (EHBLs) are blazars that exhibit extremely energetic synchrotron emission. They also feature nonthermal gamma-ray emission whose peak lies in the very high-energy (VHE, E > 100 GeV) range, and in some sources exceeds 1 TeV: this is the case for hard-TeV EHBLs such as 1ES 0229+200. With the aim of increasing the EHBL population, 10 targets were observed with the MAGIC telescopes from 2010 to 2017, for a total of 265 hr of good-quality data. The data were complemented by coordinated Swift observations. The X-ray data analysis confirms that all but two sources are EHBLs. The sources show only a modest variability and a harder-when-brighter behavior, typical for this class of objects. At VHE gamma-rays, three new sources were detected and a hint of a signal was found for another new source. In each case, the intrinsic spectrum is compatible with the hypothesis of a hard-TeV nature of these EHBLs. The broadband spectral energy distributions (SEDs) of all sources are built and modeled in the framework of a single-zone, purely leptonic model. The VHE gamma-ray-detected sources were also interpreted with a spine–layer model and a proton synchrotron model. The three models provide a good description of the SEDs. However, the resulting parameters differ substantially in the three scenarios, in particular the magnetization parameter. This work presents the first mini catalog of VHE gamma-ray and multiwavelength observations of EHBLs.