Browsing by Author "Kasen, Daniel"

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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.
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    The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814
    (2021) Kilpatrick, Charles D.; Coulter, David A.; Arcavi, Iair; Brink, Thomas G.; Dimitriadis, Georgios; Filippenko, Alexei, V; Foley, Ryan J.; Howell, D. Andrew; Jones, David O.; Kasen, Daniel; Makler, Martin; Piro, Anthony L.; Rojas-Bravo, Cesar; Sand, David J.; Swift, Jonathan J.; Tucker, Douglas; Zheng, WeiKang; Allam, Sahar S.; Annis, James T.; Antilen, Juanita; Bachmann, Tristan G.; Bloom, Joshua S.; Bom, Clecio R.; Bostroem, K. Azalee; Brout, Dillon; Burke, Jamison; Butler, Robert E.; Butner, Melissa; Campillay, Abdo; Clever, Karoli E.; Conselice, Christopher J.; Cooke, Jeff; Dage, Kristen C.; de Carvalho, Reinaldo R.; de Jaeger, Thomas; Desai, Shantanu; Garcia, Alyssa; Garcia-Bellido, Juan; Gill, Mandeep S. S.; Girish, Nachiket; Hallakoun, Na'ama; Herner, Kenneth; Hiramatsu, Daichi; Holz, Daniel E.; Huber, Grace; Kawash, Adam M.; McCully, Curtis; Medallon, Sophia A.; Metzger, Brian D.; Modak, Shaunak; Morgan, Robert; Munoz, Ricardo R.; Munoz-Elgueta, Nahir; Murakami, Yukei S.; Felipe Olivares, E.; Palmese, Antonella; Patra, Kishore C.; Pereira, Maria E. S.; Pessi, Thallis L.; Pineda-Garcia, J.; Quirola-Vasquez, Jonathan; Ramirez-Ruiz, Enrico; Rembold, Sandro Barboza; Rest, Armin; Rodriguez, Osmar; Santana-Silva, Luidhy; Sherman, Nora F.; Siebert, Matthew R.; Smith, Carli; Smith, J. Allyn; Soares-Santos, Marcelle; Stacey, Holland; Stahl, Benjamin E.; Strader, Jay; Strasburger, Erika; Sunseri, James; Tinyanont, Samaporn; Tucker, Brad E.; Ulloa, Natalie; Valenti, Stefano; Vasylyev, Sergiy S.; Wiesner, Matthew P.; Zhang, Keto D.
    We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star-black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg(2) for the 90th percentile best localization), covering a total of 51 deg(2) and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an r-band decline rate of 0.68 mag day(-1), similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most -17.8 mag (50% confidence). Our data are not constraining for "red" kilonovae and rule out "blue" kilonovae with M > 0.5 M (circle dot) (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles <17 degrees assuming an initial jet opening angle of similar to 5.degrees 2 and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.