Time-resolved hadronic particle acceleration in the recurrent nova RS Ophiuchi
F. Aharonian, F. Ait Benkhali, E. O. Angüner, Halim Ashkar, Michael Backes, Vardan Baghmanyan, V. Barbosa Martins, R. Batzofin, Y. Becherini, D. Berge, K. Bernlöhr, B. Bi, M. Böttcher, C. Boisson, J. Bolmont, Mathieu de Bony de Lavergne, M. Breuhaus, Robert Brose, F. Brun, Sami Caroff, S. Casanova, M. Cerruti, T. Chand, A. Chen, Garret Cotter, J. Damascene Mbarubucyeye, A. Djannati-Ataı̈, A. Dmytriiev, Victor Doroshenko, C. Duffy, K. Egberts, J.-P. Ernenwein, S. Fegan, Kirsty Feijen, A. Fiaßon, G. Fichet de Clairfontaine, G. Fontaine, M. Füßling, S. Funk, S. Gabici, Y. A. Gallant, S. Ghafourizadeh, G. Giavitto, Luca Giunti, D. Glawion, J. F. Glicenstein, M.-H. Grondin, G. Hermann, J. A. Hinton, M. Hörbe, W. Hofmann, C. Hoischen, T. L. Holch, M. Holler, D. Horns, Zhi-Qiu Huang, M. Jamrozy, F. Jankowsky, I. Jung-Richardt, E. Kasai, K. Katarzyński, U. Katz, D. Khangulyan, B. Khélifi, S. Klepser, W. Kluźniak, Nu. Komin, Ruslan Konno, K. Kosack, D. Kostunin, S. Le Stum, A. Lemière, M. Lemoine-Goumard, J.-P. Lenain, Fabian Leuschner, T. Lohse, Anna Luashvili, I. Lypova, Jonathan Mackey, D. Malyshev, D. Malyshev, V. Marandon, ¶. Marchegiani, A. Marcowith, G. Martí-Devesa, R. Marx, G. Maurin, M. Meyer, Alison Mitchell, R. Moderski, L. Mohrmann, A. Montanari, E. Moulin, J. Muller, T. Murach, K. Nakashima, M. de Naurois, A. Nayerhoda, J. Niemiec, A. Priyana Noel
Abstract
Recurrent novae are repeating thermonuclear explosions in the outer layers of white dwarfs, due to the accretion of fresh material from a binary companion. The shock generated when ejected material slams into the companion star's wind can accelerate particles. We report very-high-energy (VHE; [Formula: see text]) gamma rays from the recurrent nova RS Ophiuchi, up to 1 month after its 2021 outburst, observed using the High Energy Stereoscopic System (H.E.S.S.). The temporal profile of VHE emission is similar to that of lower-energy giga-electron volt emission, indicating a common origin, with a 2-day delay in peak flux. These observations constrain models of time-dependent particle energization, favoring a hadronic emission scenario over the leptonic alternative. Shocks in dense winds provide favorable environments for efficient acceleration of cosmic rays to very high energies.