Examinando por Autor "Mazzali, P."
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Ítem Highly luminous supernovae associated with gamma-ray bursts: I. GRB 111209A/SN 2011kl in the context of stripped-envelope and superluminous supernovae(Astronomy and Astrophysics, 2019-04-01) Kann, D. A.; Schady, P.; Olivares E., F.; Klose, S.; Rossi, A.; Perley, D. A.; Krühler, T.; Greiner, J.; Nicuesa Guelbenzu, A.; Elliott, J.; Knust, F.; Filgas, R.; Pian, E.; Mazzali, P.; Fynbo, J. P. U.; Leloudas, G.; Afonso, P. M. J.; Delvaux, C.; Graham, J. F.; Rau, A.; Schmidl, S.; Schulze, S.; Tanga, M.; Updike, A. C.; Varela, K.Context. GRB 111209A, one of the longest gamma-ray bursts (GRBs) ever observed, is linked to SN 2011kl, which is the most luminous GRB supernova (SN) detected so far. Several lines of evidence indicate that this GRB-SN is powered by a magnetar central engine. Aims. We place SN 2011kl into the context of large samples of SNe, addressing in more detail the question of whether this GRB-SN could be radioactively powered, and whether it represents an extreme version of a GRB-SN or an underluminous superluminous SN (SLSN). Methods. We modelled SN 2011kl using SN 1998bw as a template and derived a bolometric light curve including near-infrared data. We compared the properties of SN 2011kl to literature results on stripped-envelope and SLSNe. Results. A comparison in the k,- s context, i.e. comparing SN 2011kl to SN 1998bw templates in terms of luminosity and light-curve stretch, clearly shows SN 2011kl is the most luminous GRB-SN to date and is spectrally very dissimilar to other events because it is significantly bluer/hotter. Although SN 2011kl does not reach the classical luminosity threshold of SLSNe and evolves faster than any of these objects, it resembles SLSNe more than the classical GRB-associated broad-lined Type Ic SNe in several aspects. Conclusions. GRB 111209A was a very energetic event, both at early (prompt emission) and at very late (SN) times. We show in a companion publication that with the exception of the extreme duration, the GRB and afterglow parameters are in agreement with the known distributions for these parameters. SN 2011kl, on the other hand, is exceptional both in luminosity and spectral characteristics, indicating that GRB 111209A was likely not powered by a standard-model collapsar central engine, further supporting our earlier conclusions. Instead, it reveals the possibility of a direct link between GRBs and SLSNe.Ítem SN 2017dio: A Type-Ic Supernova Exploding in a Hydrogen-rich Circumstellar Medium(Institute of Physics Publishing, 2018-02) Kuncarayakti, H.; Maeda, K.; Ashall, C.J.; Prentice, S.J.; Mattila, S.; Kankare, E.; Fransson, C.; Lundqvist, P.; Pastorello, A.; Leloudas, G.; Anderson, J.P.; Benetti, S.; Bersten, M.C.; Cappellaro, E.; Cartier, R.; Denneau, L.; Della Valle, M.; Elias-Rosa, N.; Folatelli, G.; Fraser, M.; Galbany, L.; Gall, C.; Gal-Yam, A.; Gutiérrez, C.P.; Hamanowicz, A.; Heinze, A.; Inserra, C.; Kangas, T.; Mazzali, P.; Melandri, A.; Pignata, G.; Rest, A.; Reynolds, T.; Roy, R.; Smartt, S.J.; Smith, K.W.; Sollerman, J.; Somero, A.; Stalder, B.; Stritzinger, M.; Taddia, F.; Tomasella, L.; Tonry, J.; Weiland, H.; Young, D.R.SN 2017dio shows both spectral characteristics of a type-Ic supernova (SN) and signs of a hydrogen-rich circumstellar medium (CSM). Prominent, narrow emission lines of H and He are superposed on the continuum. Subsequent evolution revealed that the SN ejecta are interacting with the CSM. The initial SN Ic identification was confirmed by removing the CSM interaction component from the spectrum and comparing with known SNe Ic and, reversely, adding a CSM interaction component to the spectra of known SNe Ic and comparing them to SN 2017dio. Excellent agreement was obtained with both procedures, reinforcing the SN Ic classification. The light curve constrains the pre-interaction SN Ic peak absolute magnitude to be around Mg = -17.6 mag. No evidence of significant extinction is found, ruling out a brighter luminosity required by an SN Ia classification. These pieces of evidence support the view that SN 2017dio is an SN Ic, and therefore the first firm case of an SN Ic with signatures of hydrogen-rich CSM in the early spectrum. The CSM is unlikely to have been shaped by steady-state stellar winds. The mass loss of the progenitor star must have been intense, M ∼ 0.02 ϵ Hα/0.01)-1(vwind/500 km s-1) (vshock 10,000 kms-1)-3Me yr-1, peaking at a few decades before the SN. Such a high mass-loss rate might have been experienced by the progenitor through eruptions or binary stripping.Ítem SN 2020wnt: a slow-evolving carbon-rich superluminous supernova with no O II lines and a bumpy light curve(Oxford University Press, 2022-09) Gutiérrez, C.P.; Pastorello, A.; Bersten, M.; Benetti, S.; Orellana, M.; Fiore, A.; Karamehmetoglu, E.; Kravtsov, T.; Reguitti, A.; Reynolds, T.M.; Valerin, G.; Mazzali, P.; Sullivan, M.; Cai, Y.-Z.; Elias-Rosa, N.; Fraser, M.; Hsiao, E.Y.; Kankare, E.; Kotak, R.; Kuncarayakti, H.; Li, Z.; Mattila, S.; Mo, J.; Moran, S; Ochner, P.; Shahbandeh, M.; Tomasella, L.; Wang, X.; Yan, S.; Zhang, J.; Zhang, T.; Stritzinger, M. D.We present the analysis of SN 2020wnt, an unusual hydrogen-poor superluminous supernova (SLSN-I), at a redshift of 0.032. The light curves of SN 2020wnt are characterized by an early bump lasting ∼5 d, followed by a bright main peak. The SN reaches a peak absolute magnitude of Mmax r = −20.52 ± 0.03 mag at ∼77.5 d from explosion. This magnitude is at the lower end of the luminosity distribution of SLSNe-I, but the rise-time is one of the longest reported to date. Unlike other SLSNe-I, the spectra of SN 2020wnt do not show O II, but strong lines of C II and Si II are detected. Spectroscopically, SN 2020wnt resembles the Type Ic SN 2007gr, but its evolution is significantly slower. Comparing the bolometric light curve to hydrodynamical models, we find that SN 2020wnt luminosity can be explained by radioactive powering. The progenitor of SN 2020wnt is likely a massive and extended star with a pre-SN mass of 80 M and a pre-SN radius of 15 R that experiences a very energetic explosion of 45 × 1051 erg, producing 4 M of 56Ni. In this framework, the first peak results from a post-shock cooling phase for an extended progenitor, and the luminous main peak is due to a large nickel production. These characteristics are compatible with the pair-instability SN scenario. We note, however, that a significant contribution of interaction with circumstellar material cannot be ruled out.Ítem SN 2021fxy: mid-ultraviolet flux suppression is a common feature of Type Ia supernovae(Oxford University Press, 2023-07-01) DerKacy, J.M.; Paugh, S.; Baron, E.; Brown, P.J.; Ashall, C.; Burns, C.R.; Hsiao, E.Y.; Kumar, S.; Lu, J.; Morrell, N.; Phillips, M.M.; Shahbandeh, M.; Shappee, B.J.; Stritzinger, M.D.; Tucker, M.A.; Yarbrough, Z.; Boutsia, K.; Hoeflich, P.; Wang, L.; Galbany, L.; Karamehmetoglu, E.; Krisciunas, K.; Mazzali, P.; Piro, A.L.; Suntzeff, N.B.; Fiore, A.; Gutiérrez, C.P.; Lundqvist, P.; Reguitti, A.We present ultraviolet (UV) to near-infrared (NIR) observations and analysis of the nearby Type Ia supernova SN 2021fxy. Our observations include UV photometry from Swift/UVOT, UV spectroscopy from HST/STIS, and high-cadence optical photometry with the Swope 1-m telescope capturing intranight rises during the early light curve. Early B − V colours show SN 2021fxy is the first 'shallow-silicon' (SS) SN Ia to follow a red-to-blue evolution, compared to other SS objects which show blue colours from the earliest observations. Comparisons to other spectroscopically normal SNe Ia with HST UV spectra reveal SN 2021fxy is one of several SNe Ia with flux suppression in the mid-UV. These SNe also show blueshifted mid-UV spectral features and strong high-velocity Ca II features. One possible origin of this mid-UV suppression is the increased effective opacity in the UV due to increased line blanketing from high velocity material, but differences in the explosion mechanism cannot be ruled out. Among SNe Ia with mid-UV suppression, SNe 2021fxy and 2017erp show substantial similarities in their optical properties despite belonging to different Branch subgroups, and UV flux differences of the same order as those found between SNe 2011fe and 2011by. Differential comparisons to multiple sets of synthetic SN Ia UV spectra reveal this UV flux difference likely originates from a luminosity difference between SNe 2021fxy and 2017erp, and not differing progenitor metallicities as suggested for SNe 2011by and 2011fe. These comparisons illustrate the complicated nature of UV spectral formation, and the need for more UV spectra to determine the physical source of SNe Ia UV diversity. © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Ítem The optical/NIR afterglow of GRB 111209A: Complex yet not unprecedented(EDP Sciences, 2018-09) Kann, D.A.; Schady, P.; Olivares, E.F.; Klose, S.; Rossi, A.; Perley, D.A.; Zhang, B.; Krühler, T.; Greiner, J.; Nicuesa Guelbenzu, A.; Elliott, J.; Knust, F.; Cano, Z.; Filgas, R.; Pian, E.; Mazzali, P.; Fynbo, J.P.U.; Leloudas, G.; Afonso, P.M.J.; Delvaux, C.; Graham, J.F.; Rau, A.; Schmidl, S.; Schulze, S.; Tanga, M.; Updike, A.C.; Varela, K.Context. Afterglows of gamma-ray bursts (GRBs) are simple in the most basic model, but can show many complex features. The ultra-long duration GRB 111209A, one of the longest GRBs ever detected, also has the best-monitored afterglow in this rare class of GRBs. Aims. We want to address the question whether GRB 111209A was a special event beyond its extreme duration alone, and whether it is a classical GRB or another kind of high-energy transient. The afterglow may yield significant clues. Methods. We present afterglow photometry obtained in seven bands with the GROND imager as well as in further seven bands with the Ultraviolet/Optical Telescope (UVOT) on-board the Neil Gehrels Swift Observatory. The light curve is analysed by multi-band modelling and joint fitting with power-laws and broken power-laws, and we use the contemporaneous GROND data to study the evolution of the spectral energy distribution. We compare the optical afterglow to a large ensemble we have analysed in earlier works, and especially to that of another ultra-long event, GRB 130925A. We furthermore undertake a photometric study of the host galaxy. Results. We find a strong, chromatic rebrightening event at 0.8 days after the GRB, during which the spectral slope becomes redder. After this, the light curve decays achromatically, with evidence for a break at about 9 days after the trigger. The afterglow luminosity is found to not be exceptional. We find that a double-jet model is able to explain the chromatic rebrightening. The afterglow features have been detected in other events and are not unique. Conclusions. The duration aside, the GRB prompt emission and afterglow parameters of GRB 111209A are in agreement with the known distributions for these parameters. While the central engine of this event may differ from that of classical GRBs, there are multiple lines of evidence pointing to GRB 111209A resulting from the core-collapse of a massive star with a stripped envelope. © 2018 ESO.Ítem The supernova of the MAGIC gamma-ray burst GRB 190114C(EDP Sciences, 2022-03) Melandri, A.; Izzo, L.; Pian, E.; Malesani, D.; Della Valle, M.; Rossi, A.; DAvanzo, P.; Guetta, D.; Mazzali, P.; Benetti, S.; Masetti, N.; Palazzi, E.; Savaglio, S.; Amati, L.; Antonelli, L.; Ashall, C.; Bernardini, M.; Campana, S.; Carini, R.; Covino, S.; DElia, V.; De Ugarte Postigo, A.; De Pasquale, M.; Filippenko, A.; Fruchter, A.; Fynbo, J.; Giunta, A.; Hartmann, D.; Jakobsson, P.; Japelj, J.; Jonker, P.; Kann, D.; Lamb, G.; Levan, A.; Martin-Carrillo, A.; Møller, P.; Piranomonte, S.; Pugliese, G.; Salvaterra, R.; Schulze, S.; Starling, R.; Stella, L.; Tagliaferri, G.; Tanvir, N.; Watson, D.We observed GRB 190114C (redshift z = 0.4245), the first gamma-ray burst (GRB) ever detected at TeV energies, at optical and near-infrared wavelengths with several ground-based telescopes and the Hubble Space Telescope, with the primary goal of studying its underlying supernova, SN 2019jrj. The monitoring spanned the time interval between 1.3 and 370 days after the burst, in the observer frame. We find that the afterglow emission can be modelled with a forward shock propagating in a uniform medium modified by time-variable extinction along the line of sight. A jet break could be present after 7 rest-frame days, and accordingly the maximum luminosity of the underlying supernova (SN) ranges between that of stripped-envelope core-collapse SNe of intermediate luminosity and that of the luminous GRB-associated SN 2013dx. The observed spectral absorption lines of SN 2019jrj are not as broad as in classical GRB SNe and are instead more similar to those of less-luminous core-collapse SNe. Taking the broad-lined stripped-envelope core-collapse SN 2004aw as an analogue, we tentatively derive the basic physical properties of SN 2019jrj. We discuss the possibility that a fraction of the TeV emission of this source might have had a hadronic origin and estimate the expected high-energy neutrino detection level with IceCube.