Improving Cosmological Distance Measurements with Twin Type Ia Supernovae

Type Ia supernovae are used as "standardizable candles" for cosmological distance measurements. I will present a new method for identifying "twin" Type Ia supernovae, and I will discuss how we can use these twins to improve distance measurements. This novel approach to Type Ia supernova standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). With this method, we are able to standardize supernovae to ~0.08 mag, a reduction of ~3/4 in the variance compared to commonly used techniques. We also mitigate several important supernova systematics. I will discuss both the usage of the twins method and the data requirements to implement it. I will also present SeeChange, an ongoing HST survey looking for Type Ia supernovae in the highest-redshift, most massive clusters known to date. This survey will extend the supernova Hubble Diagram out to z~1.5, and will place strong constraints on time-varying dark energy.

Speaker: Kyle Boone, UC Berkeley, Lawrence Berkeley National Labs