Examinando por Autor "Salmaso I."

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    Forbidden hugs in pandemic times: IV. Panchromatic evolution of three luminous red novae
    (EDP Sciences, 2023-03) Pastorello A.; Valerin G.; Fraser M.; Reguitti A.; Elias-Rosa N.; Filippenko A.V.; Rojas-Bravo C.; Tartaglia L.; Reynolds T.M.; Valenti S.; Andrews J.E.; Ashall C.; Bostroem K.A.; Brink T.G.; Burke J.; Cai Y.-Z.; Cappellaro E.; Coulter D.A.; Dastidar R.; Davis K.W.; Dimitriadis G.; Fiore A.; Foley R.J.; Fugazza D.; Galbany L.; Gangopadhyay A.; Geier S.; Gutiérrez C.P.; Haislip J.; Hiramatsu D.; Holmbo S.; Howell D.A.; Hsiao E.Y.; Hung T.; Jha S.W.; Kankare E.; Karamehmetoglu E.; Kilpatrick C.D.; Kotak R.; Kouprianov V.; Kravtsov T.; Kumar S.; Li Z.-T.; Lundquist M.J.; Lundqvist P.; Matilainen K.; Mazzali P.A.; McCully C.; Misra K.; Morales-Garoffolo A.; Moran S.; Morrell N.; Newsome M.; Padilla Gonzalez E.; Pan Y.-C.; Pellegrino C.; Phillips M.M.; Pignata G.; Piro A.L.; Reichart D.E.; Rest A.; Salmaso I.; Sand D.J.; Siebert M.R.; Smartt S.J.; Smith K.W.; Srivastav S.; Stritzinger M.D.; Taggart K.; Tinyanont S.; Yan S.-Y.; Wang L.; Wang X.-F.; Williams S.C.; Wyatt S.; Zhang T.-M.; De Boer T.; Chambers K.; Gao H.; Magnier E.
    We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT 2018bwo, AT 2021afy, and AT 2021blu. AT 2018bwo was discovered in NGC 45 (at about 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 1040 erg s1. AT 2021afy, hosted by UGC 10043 (49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(±0.6) - 1041 erg s1. Finally, for AT 2021blu in UGC 5829 (∼8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT 2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of LRN AT 2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5 - 1040 erg s1, which is half of that of AT 2021afy. The spectra of AT 2021afy and AT 2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT 2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT 2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from about 13 M for AT 2018bwo, to 141+4 M⊙ for AT 2021blu, and over 40 M for AT 2021afy. © 2023 The Authors.
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    Hidden shock powering the peak of SN 2020faa
    (EDP Sciences, 2023) Salmaso I.; Cappellaro E.; Tartaglia L.; Benetti S.; Botticella M.T.; Elias-Rosa N.; Pastorello A.; Patat F.; Reguitti A.; Tomasella L; Valerin G.; Yang S.
    Context. The link between the fate of the most massive stars and the resulting supernova (SN) explosion is still a matter of debate, in major part because of the ambiguity among light-curve powering mechanisms. When stars explode as SNe, the light-curve luminosity is typically sustained by a central engine (radioactive decay, magnetar spin-down, or fallback accretion). However, since massive stars eject considerable amounts of material during their evolution, there may be a significant contribution coming from interactions with the previously ejected circumstellar medium (CSM). Reconstructing the progenitor configuration at the time of explosion requires a detailed analysis of the long-term photometric and spectroscopic evolution of the related transient. Aims. In this paper, we present the results of our follow-up campaign of SN 2020faa. Given the high luminosity and peculiar slow light curve, it is purported to have a massive progenitor. We present the spectro-photometric dataset and investigate different options to explain the unusual observed properties that support this assumption. Methods. We computed the bolometric luminosity of the supernova and the evolution of its temperature, radius, and expansion velocity. We also fit the observed light curve with a multi-component model to infer information on the progenitor and the explosion mechanism. Results. Reasonable parameters are inferred for SN 2020faa with a magnetar of energy, Ep = 1.5-0.2+0.5 × 1050 erg, and spin-down time, tspin = 15 ± 1 d, a shell mass, Mshell = 2.4-0.4+0.5 Mo, and kinetic energy, Ekin(shell) = 0.9-0.3+0.5 × 1051 erg, and a core with Mcore = 21.5-0.7+1.4 Mo and Ekin(core) = 3.9-0.4+0.1 × 1051 erg. In addition, we need an extra source to power the luminosity of the second peak. We find that a hidden interaction with either a CSM disc or several delayed and choked jets is a viable mechanism for supplying the required energy to achieve this effect. © The Authors 2023.