1201.1279 (P. A. Milne et al.)
P. A. Milne, P. J. Brown
Observations in the near- and mid-ultraviolet (NUV: 2000--3500$\AA$)
performed with the NASA Swift UVOT instrument have revealed that
optically-normal SNe Ia feature NUV-optical color evolution that can be divided
into NUV-blue and NUV-red groups, with roughly one-third of the observed events
exhibiting NUV-blue color curves. Combined with an apparent correlation between
NUV-blue events and the detection of unburned carbon in the optical spectra,
the grouping might point to a fundamental difference within the normal SN Ia
classfication. Recognizing the dramatic temporal evolution of the NUV-optical
colors for all SNe Ia, as well as the existence of this sub-division, is
important for studies that compare nearby SNe Ia with intermediate or high-$z$
events, for the purpose of the cosmological utilization of SNe Ia. SN 2011fe is
shown to be of the NUV-blue groups, which will be useful towards interpretation
of the gamma-ray line results from the INTEGRAL SPI campaign on SN 2011fe.
View original:
http://arxiv.org/abs/1201.1279
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