Examinando por Autor "Filippenko, A. V."

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    EXTENSIVE SPECTROSCOPY AND PHOTOMETRY OF THE TYPE IIP SUPERNOVA 2013ej
    (IOP PUBLISHING, 2016) Dhungana, G.; Kehoe, R.; Vinko, J.; Silverman, J. M.; Wheeler, J. C.; Zheng, W.; Marion, G. H.; Fox, O. D.; Akerlof, C.; Biro, B. I.; Borkovits, T.; Cenko, S. B.; Clubb, K. I.; Filippenko, A. V.; Ferrante, F. V.; Gibson, C. A.; Graham, M. L.; Hegedus, T.; Kelly, P.; Kelemen, J.; Lee, W. H.; Marschalko, G.; Molnár, L.; Nagy, A. P.; Ordasi, A.; Pal, A.; Sarneczky, K.; Shivvers, I.; Szakats, R.; Szalai, T.; Szegedi-Elek, E.; Székely, P.; Szing, A.; Takáts, K.; Vida, K.
    We present extensive optical (UBV RI, g' r' i' z', and open CCD) and near-infrared (ZY JH) photometry for the very nearby Type IIP SN. 2013ej extending from + 1 to + 461 days after shock breakout, estimated to be MJD 56496.9 +/- 0.3. Substantial time series ultraviolet and optical spectroscopy obtained from + 8 to + 135 days are also presented. Considering well-observed SNe IIP from the literature, we derive UBV RIJHK bolometric calibrations from UBV RI and unfiltered measurements that potentially reach 2% precision with a B - V color-dependent correction. We observe moderately strong Si II lambda 6355 as early as + 8 days. The photospheric velocity (vph) is determined by modeling the spectra in the vicinity of Fe II lambda 5169 whenever observed, and interpolating at photometric epochs based on a semianalytic method. This gives vph= 4500. 500 km s(-1) at + 50 days. We also observe spectral homogeneity of ultraviolet spectra at + 10-12 days for SNe IIP, while variations are evident a week after explosion. Using the expanding photosphere method, from combined analysis of SN 2013ej and SN 2002ap, we estimate the distance to the host galaxy to be 9.0(-0.6)(+0.4) Mpc, consistent with distance estimates from other methods. Photometric and spectroscopic analysis during the plateau phase, which we estimated to be 94 +/- 7 days long, yields an explosion energy of 0.9 +/- 0.3 x 10(51) erg, a final pre-explosion progenitor mass of 15.2 +/- 4.2 M-circle dot and a radius of 250 +/- 70 R-circle dot. We observe a broken exponential profile beyond + 120 days, with a break point at + 183 +/- 16 days. Measurements beyond this break time yield a Ni-56 mass of 0.013 +/- 0.001. M-circle dot.
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    LIGHT CURVES OF 213 TYPE Ia SUPERNOVAE FROM THE ESSENCE SURVEY
    (IOP PUBLISHING, 2016) Narayan, G.; Rest, A.; Tucker, B. E.; Foley, R. J.; Wood-Vasey, W. M.; Challis, P.; Stubbs, C.; Kirshner, R. P.; Aguilera, C.; Becker, A. C.; Blondin, S.; Clocchiatti, A.; Covarrubias, R.; Damke, G.; Davis, T. M.; Filippenko, A. V.; Ganeshalingam, M.; Garg, A.; Garnavich, P. M.; Hicken, M.; Jha, S. W.; Krisciunas, K.; Leibundgut, B.; Li, W.; Matheson, T.; Miknaitis, G.; Pignata, G.; Prieto, J. L.; Riess, A. G.; Schmidt, B. P.; Silverman, J. M.; Smith, R. C.; Sollerman, J.; Spyromilio, J.; Suntzeff, N. B.; Tonry, J. L.; Zenteno, A.
    The ESSENCE survey discovered 213 Type Ia supernovae at redshifts 0.1 < z < 0.81 between 2002 and 2008. We present their R- and I-band photometry, measured from images obtained using the MOSAIC II camera at the CTIO Blanco, along with rapid-response spectroscopy for each object. We use our spectroscopic follow-up observations to determine an accurate, quantitative classification, and precise redshift. Through an extensive calibration program we have improved the precision of the CTIO Blanco natural photometric system. We use several empirical metrics to measure our internal photometric consistency and our absolute calibration of the survey. We assess the effect of various potential sources of systematic bias on our measured fluxes, and estimate the dominant term in the systematic error budget from the photometric calibration on our absolute fluxes is similar to 1%.
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    Ultraviolet diversity of Type Ia Supernovae
    (OXFORD UNIV PRESS, 2016-06) Foley, Ryan J.; Pan, Yen-Chen; Brown, P.; Filippenko, A. V.; Fox, O. D.; Hillebrandt, W.; Kirshner, R. P.; Marion, G. H.; Milne, P. A.; Parrent, J. T.; Pignata, G.; Stritzinger, M. D.
    Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blueward of 2900 angstrom. We focus on spectra taken within 5 d of maximum brightness. Our sample of 10 SNe Ia spans, the majority of the parameter space of SN Ia optical diversity. We find that SNe Ia have significantly more diversity in the UV than in the optical, with the spectral variance continuing to increase with decreasing wavelengths until at least 1800 angstrom (the limit of our data). The majority of the UV variance correlates with optical light-curve shape, while there are no obvious and unique correlations between spectral shape and either ejecta velocity or host-galaxy morphology. Using light-curve shape as the primary variable, we create a UV spectral model for SNe Ia at peak brightness. With the model, we can examine how individual SNe vary relative to expectations based on only their light-curve shape. Doing this, we confirm an excess of flux for SN 2011fe at short wavelengths, consistent with its progenitor having a subsolar metallicity. While most other SNe Ia do not show large deviations from the model, ASASSN-14lp has a deficit of flux at short wavelengths, suggesting that its progenitor was relatively metal rich.