CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission
Abstract
The Galactic magnetar SGR 1935+2154 has exhibited prolific high-energy (HE) bursting activity in recent years. Investigating its potential tera-electronvolt counterpart could provide insights into the underlying mechanisms of magnetar emission and very high-energy (VHE) processes in extreme astrophysical environments. We aim to search for a possible tera-electronvolt counterpart to both its persistent and sub-second-scale burst emission. We analysed over 25 h of observations from the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) during periods of HE activity from SGR 1935+2154 in 2021 and 2022 to search for persistent emission. For bursting emission, we selected and analysed nine 0.1 s time windows centred around known short X-ray bursts, targeting potential sub-second-scale tera-electronvolt counterparts in a low-photon-statistics regime. While no persistent or bursting emission was detected in our search, we establish upper limits for the tera-electronvolt emission of a short magnetar burst simultaneous to its soft gamma-ray flux. Specifically, for the brightest burst in our sample, the ratio between tera-electronvolt and X-ray flux is less than . The non-detection of either persistent or bursting tera-electronvolt emission from SGR 1935+2154 suggests that if such components exist, they may occur under specific conditions not covered by our observations. This aligns with theoretical predictions of VHE components in magnetar-powered fast radio bursts and the detection of MeV - GeV emission in giant magnetar flares. These findings underscore the potential of magnetars, fast radio bursts, and other fast transients as promising candidates for future observations in the low-photon-statistics regime with Imaging Atmospheric Cherenkov Telescopes, particularly with the CTAO.
Keywords
Cite
@article{arxiv.2512.05634,
title = {CTAO LST-1 observations of magnetar SGR 1935+2154: Deep limits on sub-second bursts and persistent tera-electronvolt emission},
author = {K. Abe and S. Abe and A. Abhishek and F. Acero and A. Aguasca-Cabot and I. Agudo and C. Alispach and D. Ambrosino and F. Ambrosino and L. A. Antonelli and C. Aramo and A. Arbet-Engels and C. Arcaro and T. T. H. Arnesen and K. Asano and P. Aubert and A. Baktash and M. Balbo and A. Bamba and A. Baquero Larriva and U. Barres de Almeida and J. A. Barrio and L. Barrios Jiménez and I. Batkovic and J. Baxter and J. Becerra González and E. Bernardini and J. Bernete and A. Berti and I. Bezshyiko and C. Bigongiari and E. Bissaldi and O. Blanch and G. Bonnoli and P. Bordas and G. Borkowski and G. Brunelli and A. Bulgarelli and M. Bunse and I. Burelli and L. Burmistrov and M. Cardillo and S. Caroff and A. Carosi and R. Carraro and M. S. Carrasco and F. Cassol and N. Castrejón and D. Cerasole and G. Ceribella and A. Cerviño Cortínez and Y. Chai and K. Cheng and A. Chiavassa and M. Chikawa and G. Chon and L. Chytka and G. M. Cicciari and A. Cifuentes and J. L. Contreras and J. Cortina and H. Costantini and M. Dalchenko and P. Da Vela and F. Dazzi and A. De Angelis and M. de Bony de Lavergne and R. Del Burgo and C. Delgado and J. Delgado Mengual and M. Dellaiera and D. della Volpe and B. De Lotto and L. Del Peral and R. de Menezes and G. De Palma and C. Díaz and A. Di Piano and F. Di Pierro and R. Di Tria and L. Di Venere and R. M. Dominik and D. Dominis Prester and A. Donini and D. Dorner and M. Doro and L. Eisenberger and D. Elsässer and G. Emery and J. Escudero and V. Fallah Ramazani and F. Ferrarotto and A. Fiasson and L. Foffano and F. Frías García-Lago and S. Fröse and Y. Fukazawa and S. Gallozzi and R. Garcia López and S. Garcia Soto and C. Gasbarra and D. Gasparrini and D. Geyer and J. Giesbrecht Paiva and N. Giglietto and F. Giordano and N. Godinovic and T. Gradetzke and R. Grau and D. Green and J. Green and S. Gunji and P. G"unther and J. Hackfeld and D. Hadasch and A. Hahn and M. Hashizume and T. Hassan and K. Hayashi and L. Heckmann and M. Heller and J. Herrera Llorente and K. Hirotani and D. Hoffmann and D. Horns and J. Houles and M. Hrabovsky and D. Hrupec and D. Hui and M. Iarlori and R. Imazawa and T. Inada and Y. Inome and S. Inoue and K. Ioka and M. Iori and T. Itokawa and A. Iuliano and J. Jahanvi and I. Jimenez Martinez and J. Jimenez Quiles and I. Jorge Rodrigo and J. Jurysek and M. Kagaya and O. Kalashev and V. Karas and H. Katagiri and D. Kerszberg and T. Kiyomot and Y. Kobayashi and K. Kohri and A. Kong and P. Kornecki and H. Kubo and J. Kushida and B. Lacave and M. Lainez and G. Lamanna and A. Lamastra and L. Lemoigne and M. Linhoff and S. Lombardi and F. Longo and R. López-Coto and M. López-Moya and A. López-Oramas and S. Loporchio and A. Lorini and J. Lozano Bahilo and F. Lucarelli and H. Luciani and P. L. Luque-Escamilla and P. Majumdar and M. Makariev and M. Mallamaci and D. Mandat and M. Manganaro and D. K. Maniadakis and G. Manicò and K. Mannheim and S. Marchesi and F. Marini and M. Mariotti and P. Marquez and G. Marsella and J. Martí and O. Martinez and G. Martínez and M. Martínez and A. Mas-Aguilar and M. Massa and G. Maurin and D. Mazin and J. Méndez-Gallego and S. Menon and E. Mestre Guillen and S. Micanovic and D. Miceli and T. Miener and J. M. Miranda and R. Mirzoyan and M. Mizote and T. Mizuno and M. Molero Gonzalez and E. Molina and T. Montaruli and A. Moralejo and D. Morcuende and A. Moreno Ramos and A. Morselli and V. Moya and H. Muraishi and S. Nagataki and T. Nakamori and A. Neronov and D. Nieto Castaño and M. Nievas Rosillo and L. Nikolic and K. Nishijima and K. Noda and D. Nosek and V. Novotny and S. Nozaki and M. Ohishi and Y. Ohtani and T. Oka and A. Okumura and R. Orito and L. Orsini and J. Otero-Santos and P. Ottanelli and M. Palatiello and G. Panebianco and D. Paneque and F. R. Pantaleo and R. Paoletti and J. M. Paredes and M. Pech and M. Pecimotika and M. Peresano and F. Pfeifle and E. Pietropaolo and M. Pihet and G. Pirola and C. Plard and F. Podobnik and M. Polo and E. Prandini and M. Prouza and S. Rainò and R. Rando and W. Rhode and M. Ribó and V. Rizi and G. Rodriguez Fernandez and M. D. Rodríguez Frías and P. Romano and A. Roy and A. Ruina and E. Ruiz-Velasco and T. Saito and S. Sakurai and D. A. Sanchez and H. Sano and T. Šarić and Y. Sato and F. G. Saturni and V. Savchenko and F. Schiavone and B. Schleicher and F. Schmuckermaier and J. L. Schubert and F. Schussler and T. Schweizer and M. Seglar Arroyo and T. Siegert and G. Silvestri and A. Simongini and J. Sitarek and V. Sliusar and A. Stamerra and J. Strišković and M. Strzys and Y. Suda and A. Sunny and H. Tajima and M. Takahashi and J. Takata and R. Takeishi and P. H. T. Tam and S. J. Tanaka and D. Tateishi and T. Tavernier and P. Temnikov and Y. Terada and K. Terauchi and T. Terzic and M. Teshima and M. Tluczykont and F. Tokanai and T. Tomura and D. F. Torres and F. Tramonti and P. Travnicek and G. Tripodo and A. Tutone and M. Vacula and J. van Scherpenberg and M. Vázquez Acosta and S. Ventura and S. Vercellone and G. Verna and I. Viale and A. Vigliano and C. F. Vigorito and E. Visentin and V. Vitale and V. Voitsekhovskyi and G. Voutsinas and I. Vovk and T. Vuillaume and R. Walter and L. Wan and M. Will and J. Wójtowicz and T. Yamamoto and R. Yamazaki and Y. Yao and P. K. H. Yeung and T. Yoshida and T. Yoshikoshi and W. Zhang and S. Mereghetti and N. Parmiggiani and C. Vignali and R. Zanin},
journal= {arXiv preprint arXiv:2512.05634},
year = {2025}
}
Comments
13 pages, 5 figures. Accepted for publication in Astronomy & Astrophysics