Ryan J. Foley, Markus Kromer, G. Howie Marion, Giuliano Pignata, Maximilian D. Stritzinger, Stefan Taubenberger, Peter Challis, Alexei V. Filippenko, Gaston Folatelli, Wolfgang Hillebrandt, Eric Y. Hsiao, Robert P. Kirshner, Weidong Li, Nidia I. Morrell, Friedrich K. Roepke, Franco Ciaraldi-Schoolmann, Ivo R. Seitenzahl, Jeffrey M. Silverman, Robert A. Simcoe, Zachory K. Berta, Kevin M. Ivarsen, Elisabeth R. Newton, Melissa C. Nysewander, Daniel E. Reichart
We present the first maximum-light ultraviolet (UV) through near-infrared
(NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was
obtained nearly simultaneously by the Hubble Space Telescope at UV/optical
wavelengths and the Magellan Baade telescope at NIR wavelengths. These data
provide the opportunity to examine the entire maximum-light SN Ia
spectral-energy distribution. Since the UV region of a SN Ia spectrum is
extremely sensitive to the composition of the outer layers of the explosion,
which are transparent at longer wavelengths, this unprecedented spectrum can
provide strong constraints on the composition of the SN ejecta, and similarly
the SN explosion and progenitor system. SN 2011iv is spectroscopically normal,
but has a relatively fast decline (Delta m_15 (B) = 1.69 +/- 0.05 mag). We
compare SN 2011iv to other SNe Ia with UV spectra near maximum light and
examine trends between UV spectral properties, light-curve shape, and ejecta
velocity. We tentatively find that SNe with similar light-curve shapes but
different ejecta velocities have similar UV spectra, while those with similar
ejecta velocities but different light-curve shapes have very different UV
spectra. Through a comparison with explosion models, we find that both a
solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a
reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.
View original:
http://arxiv.org/abs/1202.5301
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