Examinando por Autor "Galbany L."
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Ítem A long life of excess: The interacting transient SN 2017hcc(EDP Sciences, 2023-01) Moran S.; Fraser M.; Kotak R.; Pastorello A.; Benetti S.; Brennan S.J.; Gutiérrez C.P.; Kankare E.; Kuncarayakti H.; Mattila S.; Reynolds T.M.; Anderson J.P.; Brown P.J.; Campana S.; Chambers K.C.; Chen T.-W.; Della Valle M.; Dennefeld M.; Elias-Rosa N.; Galbany L.; Galindo-Guil F.J.; Gromadzki M.; Hiramatsu D.; Inserra C.; Leloudas G.; Müller-Bravo T.E.; Nicholl M.; Reguitti A.; Shahbandeh M.; Smartt S.J.; Tartaglia L.; Young D.R.In this study we present the results of a five-year follow-up campaign of the long-lived type IIn supernova SN 2017hcc, found in a spiral dwarf host of near-solar metallicity. The long rise time (57 ± 2 days, ATLAS o band) and high luminosity (peaking at -20.78 ± 0.01 mag in the ATLAS o band) point towards an interaction of massive ejecta with massive and dense circumstellar material (CSM). The evolution of SN 2017hcc is slow, both spectroscopically and photometrically, reminiscent of the long-lived type IIn, SN 2010jl. An infrared (IR) excess was apparent soon after the peak, and blueshifts were noticeable in the Balmer lines starting from a few hundred days, but appeared to be fading by around +1200 d. We posit that an IR light echo from pre-existing dust dominates at early times, with some possible condensation of new dust grains occurring at epochs ≳;+800 d. © The Authors 2023.Ítem An outflow powers the optical rise of the nearby, fast-evolving tidal disruption event AT2019qiz(Oxford University Press, 2020-11) Nicholl M.; Wevers T.; Oates S.R.; Alexander K.D.; Leloudas G.; Onori F.; Jerkstrand A.; Gomez S.; Campana S.; Arcavi I.; Charalampopoulos P.; Gromadzki M.; Ihanec N.; Jonker P.G.; Lawrence A.; Mandel I.; Schulze S.; Short P.; Burke J.; McCully C.; Hiramatsu D.; Howell D.A.; Pellegrino C.; Abbot H.; Anderson J.P.; Berger E.; Blanchard P.K.; Cannizzaro G.; Chen T.-W.; Dennefeld M.; Galbany L.; Gonzalez-Gaitan S.; Hosseinzadeh G.; Inserra C.; Irani I.; Kuin P.; Muller-Bravo T.; Pineda J.; Ross N.P.; Roy R.; Smartt S.J.; Smith K.W.; Tucker B.; Wyrzykowski L.; Young D.R.At 66 Mpc, AT2019qiz is the closest optical tidal disruption event (TDE) to date, with a luminosity intermediate between the bulk of the population and the faint-and-fast event iPTF16fnl. Its proximity allowed a very early detection and triggering of multiwavelength and spectroscopic follow-up well before maximum light. The velocity dispersion of the host galaxy and fits to the TDE light curve indicate a black hole mass ~106M⊙, disrupting a star of ~1M⊙. By analysing our comprehensive UV, optical, and X-ray data, we show that the early optical emission is dominated by an outflow, with a luminosity evolution L α t2, consistent with a photosphere expanding at constant velocity (≥2000 km s-1), and a line-forming region producing initially blueshifted H and He II profiles with v = 3000-10000 km s-1. The fastest optical ejecta approach the velocity inferred from radio detections (modelled in a forthcoming companion paper from K. D. Alexander et al.), thus the same outflow may be responsible for both the fast optical rise and the radio emission - the first time this connection has been observed in a TDE. The light-curve rise begins 29 ± 2 d before maximum light, peaking when the photosphere reaches the radius where optical photons can escape. The photosphere then undergoes a sudden transition, first cooling at constant radius then contracting at constant temperature. At the same time, the blueshifts disappear from the spectrum and Bowen fluorescence lines (N III) become prominent, implying a source of far-UV photons, while the X-ray light curve peaks at ~1041erg s-1. Assuming that these X-rays are from prompt accretion, the size and mass of the outflow are consistent with the reprocessing layer needed to explain the large optical to X-ray ratio in this and other optical TDEs, possibly favouring accretion-powered over collision-powered outflow models. © 2020 Oxford University Press. All rights reserved.Ítem Early observations of the nearby Type Ia supernova SN 2015F(Oxford University Press, 2017-02) Cartier R.; Sullivan M.; Firth R.E.; Pignata G.; Mazzali P.; Maguire K.; Childress M.J.; Arcavi I.; Ashall C.; Bassett B.; Crawford S.M.; Frohmaier C.; Galbany L.; Gal-Yam A.; Hosseinzadeh G.; Howell D.A.; Inserra C.; Johansson J.; Kasai E.K.; McCully C.; Prajs S.; Prentice S.; Schulze S.; Smartt S.J.; Smith K.W.; Smith M.; Valenti S.; Young D.R.We present photometry and time series spectroscopy of the nearby Type Ia supernova (SN Ia) SN 2015F over -16 d to +80 d relative to maximum light, obtained as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2015F is a slightly sub-luminous SN Ia with a decline rate of Δm15(B) = 1.35 ± 0.03 mag, placing it in the region between normal and SN 1991bg-like events. Our densely sampled photometric data place tight constraints on the epoch of first light and form of the early-time light curve. The spectra exhibit photospheric C II λ6580 absorption until -4 days, and high-velocity Ca II is particularly strong at < -10 d at expansion velocities of ≃23 000 km s-1. At early times, our spectral modelling with SYN++ shows strong evidence for iron-peak elements (Fe II, Cr II, Ti II, and VII) expanding at velocities > 14 000 km s-1, suggesting mixing in the outermost layers of the SN ejecta. Although unusual in SN Ia spectra, including VII in themodelling significantly improves the spectral fits. Intriguingly, we detect an absorption feature at~6800Åthat persists until maximum light.Our favoured explanation for this line is photospheric Al II, which has never been claimed before in SNe Ia, although detached high-velocity CII material could also be responsible. In both cases, the absorbing material seems to be confined to a relatively narrow region in velocity space. The nucleosynthesis of detectable amounts of Al II would argue against a low-metallicity white dwarf progenitor.We also show that this 6800 Å feature is weakly present in other normal SN Ia events and common in the SN 1991bg-like sub-class. © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Ítem 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.Ítem Investigating the diversity of supernovae type Iax: A MUSE and NOT spectroscopic study of their environments(Oxford University Press, 2018) Lyman J.D.; Taddia F.; Stritzinger M.D.; Galbany L.; Leloudas G.; Anderson J.P.; Eldridge J.J.; James P.A.; Krühler T.; Levan A.J.; Pignata G.; Stanway E.R.SN 2002cx-like Type Ia supernovae (also known as SNe Iax) represent one of the most numerous peculiar SN classes. They differ from normal SNe Ia by having fainter peak magnitudes, faster decline rates and lower photospheric velocities, displaying awide diversity in these properties. We present both integral-field and long-slit visual-wavelength spectroscopy of the host galaxies and explosion sites of SNe Iax to provide constraints on their progenitor formation scenarios. The SN Iax explosion-site metallicity distribution is similar to that of core-collapse SNe and metal poor compared to either normal SNe Ia or SN 1991T-like events. Fainter members, speculated to form distinctly from brighter SN Iax, are found at a range of metallicities, extending to very metal poor environments. Although the SN Iax explosion-sites' ages and star formation rates are comparatively older and less intense than the distribution of star-forming regions across their host galaxies, we confirm the presence of young stellar populations (SPs) at explosion environments for most SNe Iax, expanded here to a larger sample. Ages of the young SPs (several × 107 to 108 yr) are consistent with predictions for young thermonuclear and electron-capture SN progenitors. The lack of extremely young SPs at the explosion sites disfavours very massive progenitors such as Wolf-Rayet explosions with significant fallback. We find weak ionized gas in the only SN Iax host without obvious signs of star formation. The source of the ionization remains ambiguous but appears unlikely to be mainly due to young, massive stars. © 2017 The Authors.Ítem Optical and near-infrared observations of the nearby SN Ia 2017cbv(IOP Publishing Ltd, 2020-11) Wang L.; Contreras C.; Hu M.; Hamuy M.A.; Hsiao E.Y.; Sand D.J.; Anderson J.P.; Ashall C.; Burns C.R.; Chen J.; Diamond T.R.; Davis S.; Förster F.; Galbany L.; González-Gaitán S.; Gromadzki M.; Hoeflich P.; Li W.; Marion G.H.; Morrell N.; Pignata G.; Prieto J.L.; Phillips M.M.; Shahbandeh M.; Suntzeff N.B.; Valenti S.; Wang L.; Wang X.; Young D.R.; Yu L.; Zhang J.Supernova (SN) 2017cbv in NGC 5643 is one of a handful of Type Ia supernovae (SNe Ia) reported to have excess blue emission at early times. This paper presents extensive BVRIYJHKs-band light curves of SN 2017cbv, covering the phase from -16 to +125 days relative to B-band maximum light. The SN 2017cbv reached a B-band maximum of 11.710 ± 0.006mag, with a postmaximum magnitude decline of Δm15(B) = 0.990 ± 0.013 mag. The SN suffered no host reddening based on Phillips intrinsic color, the Lira-Phillips relation, and the CMAGIC diagram. By employing the CMAGIC distance modulus μ = 30.58 ± 0.05 mag and assuming H0 = 72 km s-1 Mpc-1, we found that 0.73M⊙ 56Ni was synthesized during the explosion of SN 2017cbv, which is consistent with estimates using reddening- and distance-free methods via the phases of the secondary maximum of the near-IR- (NIR-) band light curves. We also present 14 NIR spectra from -18 to +49 days relative to the B-band maximum light, providing constraints on the amount of swept-up hydrogen from the companion star in the context of the single degenerate progenitor scenario. No Paβ emission feature was detected from our postmaximum NIR spectra, placing a hydrogen mass upper limit of 0.1 M⊙. The overall optical/NIR photometric and NIR spectral evolution of SN 2017cbv is similar to that of a normal SN Ia, even though its early evolution is marked by a flux excess not seen in most other wellobserved normal SNe Ia. We also compare the exquisite light curves of SN 2017cbv with some Mch delayed detonation models and sub-Mch double detonation models. © 2020. The American Astronomical Society.Ítem SN 2017gmr: An Energetic Type II-P Supernova with Asymmetries(Institute of Physics Publishing, 2019-11-01) Andrews, Jennifer E.; Sand D.J.; Valenti S.; Smith, Nathan; Dastidar, Raya; Sahu D.K.; Misra, Kuntal; Singh, Avinash; Hiramatsu D.; Brown P.J.; Hosseinzadeh G.; Wyatt S.; Vinko J.; Anupama G.C.; Arcavi I.; Ashall, Chris; Benetti S.; Berton, Marco; Bostroem K.A.; Bulla M.; Burke J.; Chen S.; Chomiuk L.; Cikota A.; Congiu E.; Cseh B.; Davis, Scott; Elias-Rosa N.; Faran T.; Fraser, Morgan; Galbany L.; Gall C.; Gal-Yam A.; Gangopadhyay, Anjasha; Gromadzki M.; Haislip J.; Howell D.A.; Hsiao E.Y.; Inserra C.; Kankare E.; Kuncarayakti H.; Kouprianov V.; Kumar, Brajesh; Li, Xue; Lin, Han; Maguire K.; Mazzali P.; McCully C.; Milne P.; Mo, Jun; Morrell N.; Nicholl M.; Ochner P.; Olivares F.; Pastorello A.; Patat F.; Phillips M.; Pignata G.; Prentice S.; Reguitti A.; Reichart D.E.; Rodríguez Ó.; Rui, Liming; Sanwal, Pankaj; Sárneczky K.; Shahbandeh M.; Singh, Mridweeka; Smartt S.; Strader J.; Stritzinger M.D.; Szakáts R.; Tartaglia L.; Wang, Huijuan; Wang, Lingzhi; Wang, Xiaofeng; Wheeler J.C.; Xiang, Danfeng; Yaron O.; Young D.R.; Zhang, JunboWe present high-cadence UV, optical, and near-infrared data on the luminous Type II-P supernova SN 2017gmr from hours after discovery through the first 180 days. SN 2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical light-curve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early light curve indicates a ∼500 R o progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate that up to 0.130 ± 0.026 M o of 56Ni are present, if the light curve is solely powered by radioactive decay, although the 56Ni mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multipeaked emission lines of Hα and [O i] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first 2 days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta.Ítem SN 2017ivv: Two years of evolution of a transitional Type II supernova(Oxford University Press, 2020-11) Gutiérrez C.P.; Pastorello A.; Jerkstrand A.; Galbany L.; Sullivan M.; Anderson J.P.; Taubenberger S.; Kuncarayakti H.; González-Gaitán S.; Wiseman P.; Inserra C.; Fraser M.; Maguire K.; Smartt S.; Müller-Bravo T.E.; Arcavi I.; Benetti S.; Bersier D.; Bose S.; Bostroem K.A.; Burke J.; Chen P.; Chen T.-W.; Della Valle M.; Dong S.; Gal-Yam A.; Gromadzki M.; Hiramatsu D.; Holoien T.W.-S.; Hosseinzadeh G.; Howell D.A.; Kankare E.; Kochanek C.S.; McCully C.; Nicholl M.; Pignata G.; Prieto J.L.; Shappee B.; Taggart K.; Tomasella L.; Valenti S.; Young D.R.We present the photometric and spectroscopic evolution of the Type II supernova (SN II) SN 2017ivv (also known as ASASSN- 17qp). Located in an extremely faint galaxy (Mr =-10.3 mag), SN 2017ivv shows an unprecedented evolution during the 2 yr of observations. At early times, the light curve shows a fast rise (~6-8 d) to a peak of Mmaxg = -17.84 mag, followed by a very rapid decline of 7.94 ± 0.48 mag per 100 d in the V band. The extensive photometric coverage at late phases shows that the radioactive tail has two slopes, one steeper than that expected from the decay of 56Co (between 100 and 350 d), and another slower (after 450 d), probably produced by an additional energy source. From the bolometric light curve, we estimated that the amount of ejected 56Ni is ~0.059 ± 0.003M⊙. The nebular spectra of SN 2017ivv show a remarkable transformation that allows the evolution to be split into three phases: (1) Ha strong phase ([removed]500 d).We find that the nebular analysis favours a binary progenitor and an asymmetric explosion. Finally, comparing the nebular spectra of SN 2017ivv to models suggests a progenitor with a zero-age main-sequence mass of 15-17M⊙. © 2020 The Author(s).