UV Properties of Type Ia Supernova and their Host Galaxies

TL;DR

This study uses UV observations of nearly 700 Type Ia supernovae and their host galaxies to investigate progenitor models, environmental effects, and factors influencing their use as cosmological distance indicators.

Contribution

It provides new constraints on SN Ia progenitors by ruling out shock heating signatures and explores environmental influences on supernova luminosity and distance measurements.

Findings

No evidence of shock heating from red giant companions.

Some high-redshift elliptical galaxies show ongoing star formation.

SN Ia distance residuals correlate with host galaxy UV-optical color.

Abstract

Type Ia Supernova(SN Ia) are a powerful, albeit not completely understood, tool for cosmology. Gaps in our understanding of their progenitors and detailed physics can lead to systematic errors in the cosmological distances they measure. We use UV data in two context to help further our understanding of SN Ia progenitors and physics. We analyze a set of nearly 700 light curves, and find no signature of the shock heating of a red giant companion, predicted by Kasen (2010), casting doubt as to frequency of this SN Ia channel. We also use UV imaging of high redshift host galaxies of SN Ia to better understand the environments which SN Ia occur. We show that some high-z elliptical galaxies have current star formation, hindering efforts to use them as low-extinction environments. We show cosmological scatter of SN distances at large effective radii in their hosts is significantly reduced, and argue this is due to the smaller amounts of dust affecting the SN Ia. Finally, we find a two component dependance of SN distance measurements as a function of their host galaxy's FUV-V color. This indicates that both the age and metallicity/mass of the host galaxy maybe important ingredients in measuring SN Ia distances.