Browsing by Author "Davis, K. W."

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    Final Moments. II. Observational Properties and Physical Modeling of Circumstellar-material-interacting Type II Supernovae
    (2024) Jacobson-Galan, W. V.; Dessart, L.; Davis, K. W.; Kilpatrick, C. D.; Margutti, R.; Foley, R. J.; Chornock, R.; Terreran, G.; Hiramatsu, D.; Newsome, M.; Padilla Gonzalez, E.; Pellegrino, C.; Howell, D. A.; Filippenko, A. V.; Anderson, J. P.; Angus, C. R.; Auchettl, K.; Bostroem, K. A.; Brink, T. G.; Cartier, R.; Coulter, D. A.; de Boer, T.; Drout, M. R.; Earl, N.; Ertini, K.; Farah, J. R.; Farias, D.; Gall, C.; Gao, H.; Gerlach, M. A.; Guo, F.; Haynie, A.; Hosseinzadeh, G.; Ibik, A. L.; Jha, S. W.; Jones, D. O.; Langeroodi, D.; Lebaron, N.; Magnier, E. A.; Piro, A. L.; Raimundo, S. I.; Rest, A.; Rest, S.; Rich, R. Michael; Rojas-Bravo, C.; Sears, H.; Taggart, K.; Villar, V. A.; Wainscoat, R. J.; Wang, X-f.; Wasserman, A. R.; Yan, S.; Yang, Y.; Zhang, J.; Zheng, W.
    We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time (delta(t) < 2 days) spectra show transient, narrow emission lines from shock ionization of confined (r < 10(15) cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i, He i/ii, C iv, and N iii/iv/v from the CSM persist on a characteristic timescale (t(IIn)) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early time IIn-like features in addition to 35 "comparison" SNe with no evidence of early time IIn-like features, all with ultraviolet observations. The total sample includes 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both t(II)n and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through the matching of peak multiband absolute magnitudes, rise times, t(IIn), and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: t(IIn) approximate to 3.8[M/ (0.01 M-circle dot yr(-1))] days.