Browsing by Author "Blondin, Stephane"

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    Ground-based and JWST Observations of SN 2022pul. I. Unusual Signatures of Carbon, Oxygen, and Circumstellar Interaction in a Peculiar Type Ia Supernova
    (2024) Siebert, Matthew R.; Kwok, Lindsey A.; Johansson, Joel; Jha, Saurabh W.; Blondin, Stephane; Dessart, Luc; Foley, Ryan J.; Hillier, D. John; Larison, Conor; Pakmor, Ruediger; Temim, Tea; Andrews, Jennifer E.; Auchettl, Katie; Badenes, Carles; Barna, Barnabas; Bostroem, K. Azalee; Brenner Newman, Max J.; Brink, Thomas G.; Bustamante-Rosell, Maria Jose; Camacho-Neves, Yssavo; Clocchiatti, Alejandro; Coulter, David A.; Davis, Kyle W.; Deckers, Maxime; Dimitriadis, Georgios; Dong, Yize; Farah, Joseph; Filippenko, Alexei V.; Floers, Andreas; Fox, Ori D.; Garnavich, Peter; Gonzalez, Estefania Padilla; Graur, Or; Hambsch, Franz-Josef; Hosseinzadeh, Griffin; Howell, D. Andrew; Hughes, John P.; Kerzendorf, Wolfgang E.; Le Saux, Xavier K.; Maeda, Keiichi; Maguire, Kate; McCully, Curtis; Mihalenko, Cassidy; Newsome, Megan; O'Brien, John T.; Pearson, Jeniveve; Pellegrino, Craig; Pierel, Justin D. R.; Polin, Abigail; Rest, Armin; Rojas-Bravo, Cesar; Sand, David J.; Schwab, Michaela; Shahbandeh, Melissa; Shrestha, Manisha; Smith, Nathan; Strolger, Louis-Gregory; Szalai, Tamas; Taggart, Kirsty; Terreran, Giacomo; Terwel, Jacco H.; Tinyanont, Samaporn; Valenti, Stefano; Vinko, Jozsef; Wheeler, J. Craig; Yang, Yi; Zheng, Weikang; Ashall, Chris; DerKacy, James M.; Galbany, Lluis; Hoeflich, Peter; Hsiao, Eric; de Jaeger, Thomas; Lu, Jing; Maund, Justyn; Medler, Kyle; Morrell, Nidia; Shappee, Benjamin J.; Stritzinger, Maximilian; Suntzeff, Nicholas; Tucker, Michael; Wang, Lifan
    Nebular-phase observations of peculiar Type Ia supernovae (SNe Ia) provide important constraints on progenitor scenarios and explosion dynamics for both these rare SNe and the more common, cosmologically useful SNe Ia. We present observations from an extensive ground- and space-based follow-up campaign to characterize SN 2022pul, a super-Chandrasekhar mass SN Ia (alternatively "03fg-like" SN), from before peak brightness to well into the nebular phase across optical to mid-infrared (MIR) wavelengths. The early rise of the light curve is atypical, exhibiting two distinct components, consistent with SN Ia ejecta interacting with dense carbon-oxygen (C/O)-rich circumstellar material (CSM). In the optical, SN 2022pul is most similar to SN 2012dn, having a low estimated peak luminosity (M B = -18.9 mag) and high photospheric velocity relative to other 03fg-like SNe. In the nebular phase, SN 2022pul adds to the increasing diversity of the 03fg-like subclass. From 168 to 336 days after peak B-band brightness, SN 2022pul exhibits asymmetric and narrow emission from [O i] lambda lambda 6300, 6364 (FWHM approximate to 2000 km s-1), strong, broad emission from [Ca ii] lambda lambda 7291, 7323 (FWHM approximate to 7300 km s-1), and a rapid Fe iii to Fe ii ionization change. Finally, we present the first ever optical-to-MIR nebular spectrum of an 03fg-like SN Ia using data from JWST. In the MIR, strong lines of neon and argon, weak emission from stable nickel, and strong thermal dust emission (with T approximate to 500 K), combined with prominent [O i] in the optical, suggest that SN 2022pul was produced by a white dwarf merger within C/O-rich CSM.
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    Ground-based and JWST Observations of SN 2022pul. II. Evidence from Nebular Spectroscopy for a Violent Merger in a Peculiar Type Ia Supernova
    (2024) Kwok, Lindsey A.; Siebert, Matthew R.; Johansson, Joel; Jha, Saurabh W.; Blondin, Stephane; Dessart, Luc; Foley, Ryan J.; Hillier, D. John; Larison, Conor; Pakmor, Ruediger; Temim, Tea; Andrews, Jennifer E.; Auchettl, Katie; Badenes, Carles; Barnabas, Barna; Bostroem, K. Azalee; Brenner Newman, Max J.; Brink, Thomas G.; Bustamante-Rosell, Maria Jose; Camacho-Neves, Yssavo; Clocchiatti, Alejandro; Coulter, David A.; Davis, Kyle W.; Deckers, Maxime; Dimitriadis, Georgios; Dong, Yize; Farah, Joseph; Filippenko, Alexei V.; Floers, Andreas; Fox, Ori D.; Garnavich, Peter; Padilla Gonzalez, Estefania; Graur, Or; Hambsch, Franz-Josef; Hosseinzadeh, Griffin; Howell, D. Andrew; Hughes, John P.; Kerzendorf, Wolfgang E.; Saux, Xavier K.; Maeda, Keiichi; Maguire, Kate; McCully, Curtis; Mihalenko, Cassidy; Newsome, Megan; O'Brien, John T.; Pearson, Jeniveve; Pellegrino, Craig; Pierel, Justin D. R.; Polin, Abigail; Rest, Armin; Rojas-Bravo, Cesar; Sand, David J.; Schwab, Michaela; Shahbandeh, Melissa; Shrestha, Manisha; Smith, Nathan; Strolger, Louis-Gregory; Szalai, Tamas; Taggart, Kirsty; Terreran, Giacomo; Terwel, Jacco H.; Tinyanont, Samaporn; Valenti, Stefano; Vinko, Jozsef; Wheeler, J. Craig; Yang, Yi; Zheng, WeiKang; Ashall, Chris; DerKacy, James M.; Galbany, Lluis; Hoeflich, Peter; de Jaeger, Thomas; Lu, Jing; Maund, Justyn; Medler, Kyle; Morell, Nidia; Shappee, Benjamin J.; Stritzinger, Maximilian; Suntzeff, Nicholas; Tucker, Michael; Wang, Lifan
    We present an analysis of ground-based and JWST observations of SN 2022pul, a peculiar "03fg-like" (or "super-Chandrasekhar") Type Ia supernova (SN Ia), in the nebular phase at 338 days postexplosion. Our combined spectrum continuously covers 0.4-14 mu m and includes the first mid-infrared spectrum of a 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. A strong, broad, centrally peaked [Ne ii] line at 12.81 mu m was previously predicted as a hallmark of "violent merger" SN Ia models, where dynamical interaction between two sub-M-Ch white dwarfs (WDs) causes disruption of the lower-mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to reproduce the optical iron emission better, and add mass in the innermost region (<2000 km s(-1)) to account for the observed narrow [O i] lambda lambda 6300, 6364 emission. A violent WD-WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SNe Ia.
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    Non-local Thermodynamic Equilibrium Radiative Transfer Simulations of Sub-Chandrasekhar-mass White Dwarf Detonations
    (2021) Shen, Ken J.; Blondin, Stephane; Kasen, Daniel; Dessart, Luc; Townsley, Dean M.; Boos, Samuel; Hillier, D. John
    Type Ia supernovae (SNe Ia) span a range of luminosities and timescales, from rapidly evolving subluminous to slowly evolving overluminous subtypes. Previous theoretical work has, for the most part, been unable to match the entire breadth of observed SNe Ia with one progenitor scenario. Here, for the first time, we apply non-local thermodynamic equilibrium radiative transfer calculations to a range of accurate explosion models of sub-Chandrasekhar-mass white dwarf detonations. The resulting photometry and spectra are in excellent agreement with the range of observed nonpeculiar SNe Ia through 15 days after the time of B-band maximum, yielding one of the first examples of a quantitative match to the entire Phillips relation. The intermediate-mass element velocities inferred from theoretical spectra at maximum light for the more massive white dwarf explosions are higher than those of bright observed SNe Ia, but these and other discrepancies likely stem from the one-dimensional nature of our explosion models and will be improved upon by future non-local thermodynamic equilibrium radiation transport calculations of multidimensional sub-Chandrasekhar-mass white dwarf detonations.
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    StaNdaRT: a repository of standardised test models and outputs for supernova radiative transfer
    (2022) Blondin, Stephane; Blinnikov, Sergei; Callan, Fionntan P.; Collins, Christine E.; Dessart, Luc; Even, Wesley; Flors, Andreas; Fullard, Andrew G.; Hillier, D. John; Jerkstrand, Anders; Kasen, Daniel; Katz, Boaz; Kerzendorf, Wolfgang; Kozyreva, Alexandra; O'Brien, Jack; Passaro, Ezequiel A.; Roth, Nathaniel; Shen, Ken J.; Shingles, Luke; Sim, Stuart A.; Singhal, Jaladh; Smith, Isaac G.; Sorokina, Elena; Utrobin, Victor P.; Vogl, Christian; Williamson, Marc; Wollaeger, Ryan; Woosley, Stan E.; Wygoda, Nahliel
    We present the first results of a comprehensive supernova (SN) radiative-transfer (RT) code-comparison initiative (StaNdaRT), where the emission from the same set of standardised test models is simulated by currently used RT codes. We ran a total of ten codes on a set of four benchmark ejecta models of Type Ia SNe. We consider two sub-Chandrasekhar-mass (M-tot = 1.0 M-circle dot) toy models with analytic density and composition profiles and two Chandrasekhar-mass delayed-detonation models that are outcomes of hydrodynamical simulations. We adopt spherical symmetry for all four models. The results of the different codes, including the light curves, spectra, and the evolution of several physical properties as a function of radius and time are provided in electronic form in a standard format via a public repository. We also include the detailed test model profiles and several Python scripts for accessing and presenting the input and output files. We also provide the code used to generate the toy models studied here. In this paper, we describe the test models, radiative-transfer codes, and output formats in detail, and provide access to the repository. We present example results of several key diagnostic features.