Ethan Marx

Type Ia supernovae (SNe Ia) are known to be the result of a thermonuclear explosion of a C/O white dwarf (WD). A satisfactory description of the progenitor system, however, has yet to be reached. The two most likely configurations for the progenitor systems includes a WD-WD binary, known as the double degenerate (DD) model, or a WD binary with a non-degenerate companion, known as the single degenerate (SD) model. Very early observations (2-3 weeks pre B band maximum) of SNe Ia can show signatures of ejecta interaction with the companion star, and thus can be helpful in determining properties of the progenitor system. However, because the angle at which we observe the SNe Ia restricts the possibility of detecting this emission, < 10% of SNe Ia are expected to show signature of this ejecta interaction (Kasen et al 2010). Through the Phillips relation (Phillips et al 1993), SNe Ia have been used as standard candles to gauge cosmological distances. However, this assumes SNe Ia can be described as a one parameter family. It has recently become more clear that the spectral and photometric features of SNe Ia are diverse, especially at early times. Understanding the relationship between the different spectroscopic and photometric features can help improve our use of SNe Ia as cosmological distance probes, as well as uncover new ideas about the progenitor systems. In my research during the Summer of 2018, we analyzed early spectral and photometric observations of SNe Ia iPTF16hvw, discovered by the intermediate Palomar Transient Factory, with the purpose of learning more about the progenitor systems of SNe Ia as a whole.

Figure 1: Spectral sequence for iPTF16hvw, compared with one of the most well observed, stanard Type Ia SN2011fe, as well as SN2002bo and SN2002dj, 2 other SN with similar spectral sequences to iPTF16hvw. Wavelength and phases are measure in the restframe of the SN. The O plus symbols refer to telluric absorption.
Figure 2: The early R band Lightcurve data, the maximum posterior fit, and 5 random draws from the posterior. We used MCMC to sample the posterior distribution. We determined a bestfit time of first light t_0 = ___, and bestfit powerlaw index of alpha = _____.