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Title: Bump Morphology of the CMAGIC Diagram

We apply the color–magnitude intercept calibration method (CMAGIC) to the Nearby Supernova Factory SNe Ia spectrophotometric data set. The currently existing CMAGIC parameters are the slope and intercept of a straight line fit to the linear region in the color–magnitude diagram, which occurs over a span of approximately 30 days after maximum brightness. We define a new parameter,ωXY, the size of the “bump” feature near maximum brightness for arbitrary filtersXandY. We find a significant correlation between the slope of the linear region,βXY, in the CMAGIC diagram andωXY. These results may be used to our advantage, as they are less affected by extinction than parameters defined as a function of time. Additionally,ωXYis computed independently of templates. We find that current empirical templates are successful at reproducing the features described in this work, particularly SALT3, which correctly exhibits the negative correlation between slope and “bump” size seen in our data. In 1D simulations, we show that the correlation between the size of the “bump” feature andβXYcan be understood as a result of chemical mixing due to large-scale Rayleigh–Taylor instabilities.

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DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Page Range / eLocation ID:
Article No. 10
Medium: X
Sponsoring Org:
National Science Foundation
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