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oai:recercat.cat:2445/695322025-12-05T16:50:01Zcom_2072_1057col_2072_478823col_2072_478904col_2072_478917

Very high-energy γ-ray observations of novae and dwarf novae with the MAGIC telescopes MAGIC Collaboration Marcote Martin, Benito Munar i Adrover, Pere Paredes i Poy, Josep Maria Paredes Fortuny, Xavier Ribó Gomis, Marc Zanin, Roberta Estels binaris de raigs X Noves (Estels) Raigs gamma X-ray binaries New stars Gamma rays Context. In the last five years the Fermi Large Area Telescope (LAT) instrument detected GeV γ-ray emission from five novae. The GeV emission can be interpreted in terms of an inverse Compton process of electrons accelerated in a shock. In this case it is expected that protons in the same conditions can be accelerated to much higher energies. Consequently they may produce a second component in the γ-ray spectrum at TeV energies. Aims: We aim to explore the very high-energy domain to search for γ-ray emission above 50 GeV and to shed light on the acceleration process of leptons and hadrons in nova explosions. Methods: We have performed observations, with the MAGIC telescopes of the classical nova V339 Del shortly after the 2013 outburst; optical and subsequent GeV γ-ray detections triggered the MAGIC observations. We also briefly report on VHE observations of the symbiotic nova YY Her and the dwarf nova ASASSN-13ax. We complement the TeV MAGIC observations with the analysis of contemporaneous Fermi-LAT data of the sources. The TeV and GeV observations are compared in order to evaluate the acceleration parameters for leptons and hadrons. Results: No significant TeV emission was found from the studied sources. We computed upper limits on the spectrum and night-by-night flux. The combined GeV and TeV observations of V339 Del limit the ratio of proton to electron luminosities to Lp ≲ 0.15 Le. 2016-02-17T12:50:38Z 2016-10-08T22:01:17Z 2015-10-08 2016-02-17T12:50:38Z info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion 0004-6361 https://hdl.handle.net/2445/69532 657110 eng Versió postprint del document publicat a: http://dx.doi.org/10.1051/0004-6361/201526478 Astronomy and Astrophysics, 2015, vol. 582, p. A67-A74 http://dx.doi.org/10.1051/0004-6361/201526478 (c) Springer Verlag, 2015 info:eu-repo/semantics/openAccess 7 p. application/pdf Springer Verlag Articles publicats en revistes (Física Quàntica i Astrofísica)