Detection of RS Oph with LST-1 and modelling of its HE/VHE gamma-ray emission
Creators: name: Project, CTA-LST
name: :
name: Abe, K.
name: Abe, S.
name: Abhishek, A.
name: Acero, F.
name: Aguasca-Cabot, A.
name: Agudo, I.
name: Alispach, C.
name: Crespo, N. Alvarez
name: Ambrosino, D.
name: Antonelli, L. A.
name: Aramo, C.
name: Arbet-Engels, A.
name: Arcaro, C.
name: Asano, K.
name: Aubert, P.
name: Baktash, A.
name: Balbo, M.
name: Bamba, A.
name: Larriva, A. Baquero
name: de Almeida, U. Barres
name: Barrio, J. A.
name: Jiménez, L. Barrios
name: Batkovic, I.
name: Baxter, J.
name: González, J. Becerra
name: Bernardini, E.
name: Bernete, J.
name: Berti, A.
name: Bezshyiko, I.
name: Bhattacharjee, P.
name: Bigongiari, C.
name: Bissaldi, E.
name: Blanch, O.
name: Bonnoli, G.
name: Bordas, P.
name: Borkowski, G.
name: Brunelli, G.
name: Bulgarelli, A.
name: Bunse, M.
name: Burelli, I.
name: Burmistrov, L.
name: Buscemi, M.
name: Cardillo, M.
name: Caroff, S.
name: Carosi, A.
name: Carrasco, M. S.
name: Cassol, F.
name: Castrejón, N.
name: Cerasole, D.
name: Ceribella, G.
name: Chai, Y.
name: Cheng, K.
name: Chiavassa, A.
name: Chikawa, M.
name: Chon, G.
name: Chytka, L.
name: Cicciari, G. M.
name: Cifuentes, A.
name: Contreras, J. L.
name: Cortina, J.
name: Costantini, H.
name: Da Vela, P.
name: Dalchenko, M.
name: Dazzi, F.
name: De Angelis, A.
name: de Lavergne, M. de Bony
name: De Lotto, B.
name: de Menezes, R.
name: Del Burgo, R.
name: Del Peral, L.
name: Delgado, C.
name: Mengual, J. Delgado
name: della Volpe, D.
name: Dellaiera, M.
name: Di Piano, A.
name: Di Pierro, F.
name: Di Tria, R.
name: Di Venere, L.
name: Díaz, C.
name: Dominik, R. M.
name: Prester, D. Dominis
name: Donini, A.
name: Dore, D.
name: Dorner, D.
name: Doro, M.
name: Eisenberger, L.
name: Elsässer, D.
name: Emery, G.
name: Escudero, J.
name: Ramazani, V. Fallah
name: Ferrarotto, F.
name: Fiasson, A.
name: Foffano, L.
name: Coromina, L. Freixas
name: Fröse, S.
name: Fukazawa, Y.
name: López, R. Garcia
name: Gasbarra, C.
name: Gasparrini, D.
name: Geyer, D.
name: Paiva, J. Giesbrecht
name: Giglietto, N.
name: Giordano, F.
name: Gliwny, P.
name: Godinovic, N.
name: Grau, R.
name: Green, D.
name: Green, J.
name: Gunji, S.
name: Günther, P.
name: Hackfeld, J.
name: Hadasch, D.
name: Hahn, A.
name: Hassan, T.
name: Hayashi, K.
name: Heckmann, L.
name: Heller, M.
name: Llorente, J. Herrera
name: Hirotani, K.
name: Hoffmann, D.
name: Horns, D.
name: Houles, J.
name: Hrabovsky, M.
name: Hrupec, D.
name: Hui, D.
name: Iarlori, M.
name: Imazawa, R.
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name: Jahanvi, J.
name: Martinez, I. Jimenez
name: Quiles, J. Jimenez
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name: López-Coto, R.
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name: Bahilo, J. Lozano
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name: Marsella, G.
name: Martí, J.
name: Martinez, O.
name: Martínez, G.
name: Martínez, M.
name: Mas-Aguilar, A.
name: Maurin, G.
name: Mazin, D.
name: Méndez-Gallego, J.
name: Menon, S.
name: Guillen, E. Mestre
name: Micanovic, S.
name: Miceli, D.
name: Miener, T.
name: Miranda, J. M.
name: Mirzoyan, R.
name: Mizuno, T.
name: Gonzalez, M. Molero
name: Molina, E.
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name: Moralejo, A.
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name: Moya, V.
name: Muraishi, H.
name: Nagataki, S.
name: Nakamori, T.
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name: Nickel, L.
name: Castaño, D. Nieto
name: Rosillo, M. Nievas
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name: Frías, M. D. Rodríguez
name: Romano, P.
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name: Ruiz-Velasco, E.
name: Saito, T.
name: Sakurai, S.
name: Sanchez, D. A.
name: Sano, H.
name: Šarić, T.
name: Sato, Y.
name: Saturni, F. G.
name: Savchenko, V.
name: Schiavone, F.
name: Schleicher, B.
name: Schmuckermaier, F.
name: Schubert, J. L.
name: Schussler, F.
name: Schweizer, T.
name: Arroyo, M. Seglar
name: Siegert, T.
name: Simongini, A.
name: Sitarek, J.
name: Sliusar, V.
name: Stamerra, A.
name: Strišković, J.
name: Strzys, M.
name: Suda, Y.
name: Sunny, A.
name: Tajima, H.
name: Takahashi, H.
name: Takahashi, M.
name: Takata, J.
name: Takeishi, R.
name: Tam, P. H. T.
name: Tanaka, S. J.
name: Tateishi, D.
name: Tavernier, T.
name: Temnikov, P.
name: Terada, Y.
name: Terauchi, K.
name: Terzic, T.
name: Teshima, M.
name: Tluczykont, M.
name: Toennis, C.
name: Tokanai, F.
name: Torres, D. F.
name: Travnicek, P.
name: Tutone, A.
name: Vacula, M.
name: van Scherpenberg, J.
name: Acosta, M. Vázquez
name: Ventura, S.
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name: Vigliano, A.
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name: Visentin, E.
name: Vitale, V.
name: Voitsekhovskyi, V.
name: Voutsinas, G.
name: Vovk, I.
name: Vuillaume, T.
name: Walter, R.
name: Wan, L.
name: Will, M.
name: Wójtowicz, J.
name: Yamamoto, T.
name: Yamazaki, R.
name: Yao, Y.
name: Yeung, P. K. H.
name: Yoshida, T.
name: Yoshikoshi, T.
name: Zhang, W.
name: Zywucka, N.
Publisher: name: arXiv
Year: 2025
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The recurrent nova RS Ophiuchi (RS Oph) underwent a thermonuclear eruption in August 2021. In this event, RS Oph was detected by the High Energy Stereoscopic System (H.E.S.S.), the Major Atmospheric Gamma Imaging Cherenkov (MAGIC), and the first Large-Sized Telescope (LST-1) of the future Cherenkov Telescope Array Observatory (CTAO) at very-high gamma-ray energies above 100 GeV. This means that novae are a new class of very-high-energy (VHE) gamma-ray emitters. We report the analysis of the RS Oph observations with LST-1. We constrain the particle population that causes the observed emission in hadronic and leptonic scenarios. Additionally, we study the prospects of detecting further novae using LST-1 and the upcoming LST array of CTAO-North. We conducted target-of-opportunity observations with LST-1 from the first day of this nova event. The data were analysed in the framework of cta-lstchain and Gammapy, the official CTAO-LST reconstruction and analysis packages. One-zone hadronic and leptonic models were considered to model the gamma-ray emission of RS Oph using the spectral information from Fermi-LAT and LST-1, together with public data from the MAGIC and H.E.S.S. telescopes. RS Oph was detected at $6.6σ$ with LST-1 in the first 6.35 hours of observations following the eruption. The hadronic scenario is preferred over the leptonic scenario considering a proton energy spectrum with a power-law model with an exponential cutoff whose position increases from $(0.26\pm 0.08)$ TeV on day 1 up to $(1.6\pm 0.6)$ TeV on day 4 after the eruption. The deep sensitivity and low energy threshold of the LST-1/LST array will allow us to detect faint novae and increase their discovery rate.
description: 18 pages, 9 figures. Published in Astronomy &amp; Astrophysics