The main focus on my first project with Dr. Hillier involved creating a gamma-ray scattering routine as a consistency check to the Monte-Carlo radiative transfer code used in CFMGEN in Hillier & Dessart (2012), which tracks photons and subsequent Compton scattering in order to quickly compute the energy deposition in supernovae. This method is subject to statistical limitations. All gamma-ray radiative transfer codes prior to my work have all been done using Monte-Carlo techniques. This work is the first of its kind that is a full radiative transfer calculation to create a synthetic spectra, by calculating for the specific intensity, and calculate energy deposition in the ejecta. Since the ejecta in Type Ia supernovae are heated by gamma-rays it is crucial to calculate the energy deposition accurately to understand how energy changes the ionization and temperature structure of the gas.
My second project focused on determining diagnostics of Type Ia supernovae. To do this, we used CMFGEN to compute a series of four Type Ia models for a range of ejecta mass (1.0 - 1.7 Msun) and the same 56Ni mass (0.6 Msun) by scaling the abundances. It is a testament to Type Ia supernovae being such a similar class of objects (despite a 70% difference in mass) that we see such similar optical spectra at most phases along with similar light curve morphologies. However, we find that our low mass Type Ia models have faster light curve evolution and bluer colors. Spectral diagnostics include less UV blanketing and higher ionization states in low mass models, caused from more heating per gram of material. Higher mass models, show stronger spectral line profiles for intermediate mass elements and in the nebular phase show a strong [Ni II] 1.939 micron not present in one of our low mass models.
Future projects with Dr. Hillier will be investigating other aspects of Type Ia supernovae for the goal of determining other diagnostics to understand the progenitor problem of Type Ia supernovae.