Examinando por Autor "Anderson J.P."
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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 Discovery and follow-up of ASASSN-19dj: An X-ray and UV luminous TDE in an extreme post-starburst galaxy(Oxford University Press, 2021-01-01) Hinkle, Jason T; Holoien T.W.; Auchettl K.; Shappee B.J.; Neustadt J.M.M.; Payne A.V.; Brown J.S.; Kochanek C.S.; Stanek K.Z.; Graham M.J.; Tucker M.A.; Do A.; Anderson J.P.; Bose S.; Chen P.; Coulter D.A.; Dimitriadis G.; Dong, Subo; Foley R.J.; Huber M.E.; Hung T.; Kilpatrick C.D.; Pignata G.; Piro A.L.; Rojas-Bravo C.; Siebert M.R.; Stalder B.; Thompson, Todd A.; Tonry J.L.; Vallely P.J.; Wisniewski J.P.We present observations of ASASSN-19dj, a nearby tidal disruption event (TDE) discovered in the post-starburst galaxy KUG 0810+227 by the All-Sky Automated Survey for Supernovae (ASAS-SN) at a distance of d ≃ 98 Mpc. We observed ASASSN-19dj from -21 to 392 d relative to peak ultraviolet (UV)/optical emission using high-cadence, multiwavelength spectroscopy and photometry. From the ASAS-SN g-band data, we determine that the TDE began to brighten on 2019 February 6.8 and for the first 16 d the rise was consistent with a flux α2 power law. ASASSN-19dj peaked in the UV/optical on 2019 March 6.5 (MJD = 58548.5) at a bolometric luminosity of L = (6.2 ± 0.2) × 1044 erg s-1. Initially remaining roughly constant in X-rays and slowly fading in the UV/optical, the X-ray flux increased by over an order of magnitude ∼225 d after peak, resulting from the expansion of the X-ray emitting region. The late-time X-ray emission is well fitted by a blackbody with an effective radius of ∼1 × 1012 cm and a temperature of ∼6 × 105 K. The X-ray hardness ratio becomes softer after brightening and then returns to a harder state as the X-rays fade. Analysis of Catalina Real-Time Transient Survey images reveals a nuclear outburst roughly 14.5 yr earlier with a smooth decline and a luminosity of LV ≥ 1.4 × 1043 erg s-1, although the nature of the flare is unknown. ASASSN-19dj occurred in the most extreme post-starburst galaxy yet to host a TDE, with Lick HδA = 7.67 ± 0.17 Å.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 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).