Curvature in the very-high energy gamma-ray spectrum of M87
Creators: name: Collaboration, H. E. S. S.
name: Aharonian, F.
name: Benkhali, F. Ait
name: Aschersleben, J.
name: Ashkar, H.
name: Backes, M.
name: Martins, V. Barbosa
name: Batzofin, R.
name: Becherini, Y.
name: Berge, D.
name: Bernlöhr, K.
name: Böttcher, M.
name: Boisson, C.
name: Bolmont, J.
name: de Lavergne, M. de Bony
name: Bradascio, F.
name: Brose, R.
name: Brun, F.
name: Bruno, B.
name: Burger-Scheidlin, T. Bulik C.
name: Bylund, T.
name: Casanova, S.
name: Cecil, R.
name: Celic, J.
name: Cerruti, M.
name: Chand, T.
name: Chandra, S.
name: Chen, A.
name: Chibueze, J.
name: Chibueze, O.
name: Collins, T.
name: Cotter, G.
name: Mbarubucyeye, J. Damascene
name: Djannati-Ataï, A.
name: Djuvsland, J.
name: Dmytriiev, A.
name: Egberts, K.
name: Einecke, S.
name: Fegan, S.
name: Fontaine, G.
name: Funk, S.
name: Gabici, S.
name: Glicenstein, J. F.
name: Glombitza, J.
name: Grolleron, G.
name: Haerer, L.
name: Hofmann, W.
name: Holch, T. L.
name: Holler, M.
name: Horns, D.
name: Jamrozy, M.
name: Jankowsky, F.
name: Joshi, V.
name: Jung-Richardt, I.
name: Kasai, E.
name: Katarzyński, K.
name: Khatoon, R.
name: Khélifi, B.
name: Kluźniak, W.
name: Komin, Nu.
name: Kosack, K.
name: Kostunin, D.
name: Kundu, A.
name: Lang, R. G.
name: Stum, S. Le
name: Leitl, F.
name: Lemière, A.
name: Lemoine-Goumard, M.
name: Lenain, J. -P.
name: Lypova, I.
name: Luashvili, A.
name: Mackey, J.
name: Malyshev, D.
name: Martí-Devesa, G.
name: Marx, R.
name: Mehta, A.
name: Meyer, M.
name: Mitchell, A.
name: Moderski, R.
name: Moghadam, M. O.
name: Mohrmann, L.
name: Montanari, A.
name: Moulin, E.
name: Murach, T.
name: de Naurois, M.
name: Niemiec, J.
name: Ohm, S.
name: Olivera-Nieto, L.
name: Wilhelmi, E. de Ona
name: Panny, S.
name: Panter, M.
name: Parsons, R. D.
name: Pensec, U.
name: Pita, S.
name: Pühlhofer, G.
name: Punch, M.
name: Quirrenbach, A.
name: Regeard, M.
name: Reimer, A.
name: Reimer, O.
name: Ren, H.
name: Reville, B.
name: Rieger, F.
name: Rudak, B.
name: Ruiz-Velasco, E.
name: Sahakian, V.
name: Salzmann, H.
name: Santangelo, A.
name: Sasaki, M.
name: Schüssler, F.
name: Schutte, H. M.
name: Shapopi, J. N. S.
name: Sol, H.
name: Spencer, S.
name: Stawarz, Ł.
name: Steenkamp, R.
name: Steinmassl, S.
name: Steppa, C.
name: Streil, K.
name: Takahashi, T.
name: Tanaka, T.
name: Taylor, A. M.
name: Terrier, R.
name: Tsirou, M.
name: van Eldik, C.
name: Venter, C.
name: Vink, J.
name: Wach, T.
name: Wagner, S. J.
name: Wierzcholska, A.
name: Zacharias, M.
name: Zdziarski, A. A.
name: Zech, A.
name: Zilberman, P.
name: Zywucka, N.
Publisher: name: arXiv
Year: 2024
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is yet to be understood. In this study, we investigate the VHE gamma-ray spectrum of M87 during states of high gamma-ray activity, utilizing 20.2$\,$ hours the H.E.S.S. observations. Our findings indicate a preference for a curved spectrum, characterized by a log-parabola model with extra-galactic background light (EBL) model above 0.3$\,$TeV at the 4$σ$ level, compared to a power-law spectrum with EBL. We investigate the degeneracy between the absorption feature and the EBL normalization and derive upper limits on EBL models mainly sensitive in the wavelength range 12.4$\,$$μ$m - 40$\,$$μ$m.
description: 10 pages, 7 figures. Accepted for publication in A&amp;A. Corresponding authors: Victor Barbosa Martins, Rahul Cecil, Iryna Lypova, Manuel Meyer, Perri Zilberman. Supplementary material: https://zenodo.org/records/10781524