Analysis of Supernova Ejecta Velocities

Abstract

A series of scripts were created in Python to isolate and measure the Si II absorption line feature in the spectra of Type Ia supernovae. This line feature was then compared to the rest wave length of Si II, and using the Doppler Shift equation, the photospheric velocities of the supernovae were determined. For each supernova studied, this procedure was repeated over various using spectra taken at various times, which were then plotted relative to the day of maximum brightness for the individual supernova, and the data was fitted to a regression line. The photospheric velocities for the day of maximum brightness and the gradient of photospheric velocity decline were recorded and compared between supernovae, and the intrinsic color of the supernovae was com pared using this data. The results indicate that the photospheric velocity at the day of maximum brightness correlates positively with the steepness of the slope of the velocity decline gradient. The photospheric velocity at peak was also compared with color and the results indicate that the correlation is negative.