MAGIC observations of the giant radio galaxy M87 in a low-emission state between 2005 and 2007

• Published in: arXiv.org
• Main Authors: Antoranz, P, Asensio, M, Backes, M, Barrio, J A, Bastieri, D, J Becerra González, Berdyugin, A, Berger, K, Bernardini, E, Biland, A, Blanch, O, Bock, R K, Boller, A, Bonnoli, G, Braun, I, Bretz, T, Cañellas, A, Carmona, E, Carosi, A, Colin, P, Cortina, J, Dazzi, F, De Angelis, A, De Caneva, G, C Delgado Mendez, A Diago Ortega, Doert, M, D Dominis Prester, Ferenc, D, Fonseca, M V, Garczarczyk, M, Garrido, D, Giavitto, G, Godinović, N, Hadasch, D, Häfner, D, Hose, J, Hrupec, D, Kellermann, H, Klepser, S, La Barbera, A, Lelas, D, Leonardo, E, Lindfors, E, Lombardi, S, López, M, López-Oramas, A, Lorenz, E, Makariev, M, Maneva, G, Mannheim, K, Martínez, M, Mazin, D, Meucci, M, Moldón, J, Moralejo, A, Munar-Adrover, P, Nieto, D, Nilsson, K, Paneque, D, Paoletti, R, Pardo, S, Paredes, J M, Pasanen, M, Persic, M, Peruzzo, L, Pilia, M, Pochon, J, Prada, F, Reichardt, I, Reinthal, R, Rhode, W, Ribó, M, Rico, J, Rügamer, S, Saito, T Y, Salvati, M, Satalecka, K, Scalzotto, V, Scapin, V, Schweizer, T, Sillanpää, A, Snidaric, I, Sobczynska, D, Spanier, F, Stamatescu, V, Stamerra, A, Storz, J, Surić, T, Takami, H, Tavecchio, F, Temnikov, P, Terzić, T, Tibolla, O, Uellenbeck, M, Vankov, H, Vogler, P, Wagner, R M, Zanin, R, Ghisellini, G
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 11.07.2012
• Subjects: Confidence intervals; Elliptical galaxies; Emission; Energy spectra; Galaxies; Monitoring; Physics - Cosmology and Nongalactic Astrophysics; Physics - High Energy Astrophysical Phenomena; Radio galaxies
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1207.2147

We present the results of a long M87 monitoring campaign in very high energy \(\gamma\)-rays with the MAGIC-I Cherenkov telescope. We aim to model the persistent non-thermal jet emission by monitoring and characterizing the very high energy \(\gamma\)-ray emission of M87 during a low state. A total of 150\,h of data were taken between 2005 and 2007 with the single MAGIC-I telescope, out of which 128.6\,h survived the data quality selection. We also collected data in the X-ray and \textit{Fermi}--LAT bands from the literature (partially contemporaneous). No flaring activity was found during the campaign. The source was found to be in a persistent low-emission state, which was at a confidence level of \(7\sigma\). We present the spectrum between 100\,GeV and 2\,TeV, which is consistent with a simple power law with a photon index \(\Gamma=2.21\pm0.21\) and a flux normalization at 300\,GeV of \((7.7\pm1.3) \times 10^{-8}\) TeV\(^{-1}\) s\(^{-1}\) m\(^{-2}\). The extrapolation of the MAGIC spectrum into the GeV energy range matches the previously published \textit{Fermi}--LAT spectrum well, covering a combined energy range of four orders of magnitude with the same spectral index. We model the broad band energy spectrum with a spine layer model, which can satisfactorily describe our data.