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L. Wang, G. Aldering (Lawrence Berkeley National Laboratory), A. V. Filippenko (University of California, Berkeley), P. Challis (CfA, Harvard), P. Nugent (Lawrence Berkeley National Laboratory), W. Li (University of California, Berkeley), T. Matheson (NOAO), A. Howell (University of Toronto)
The utility of Type Ia supernovae (SNe Ia) as cosmological probes depends on the degree of our understanding of SN Ia physics, and various systematic effects such as cosmic chemical evolution. Early-time UV spectra and light curves of nearby SNe Ia can directly address these questions. We report here detailed studies of three young, Hubble-flow SNe Ia (SN 2004dt, SN 2004ef, and SN 2005M) with Hubble Space Telescope UV spectroscopy (ACS prism) and UV photometry (ACS). These three objects represent three distinct sub-classes of SNe Ia: SN 2004dt shows high-velocity features, SN 2004ef shows optical spectral features typical of those of normal SNe Ia, and SN 2005M is a peculiar SN Ia similar to SN 1991T. The HST UV data show clear evidence of spectral differences among these three objects which can be used to probe the dust environment and metallicity of the SN ejecta. Most remarkably, SN 2004dt was found to be UV bright, consistent with the absence of Fe II features in the optical (Wang et al. 2004). These HST data, along with extensive ground-based optical to near-IR observations, can be used to probe SN Ia explosion physics and constrain the nature of the progenitors. They also form the basis of further improving the application of SNe Ia as cosmological probes.
This research is supported by NASA grant GO-10182 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.