Published: Sept. 12, 2014

Supernova classification using photometric measurements

Darren Homrighausen

Department of StatisticsColorado State University

Date and time: 

Friday, September 12, 2014 - 3:00pm


ECCR 245


The problem of supernova (SN) classification is extremely important for use in modern cosmology. There are many types of supernovae (SNe) related to the physical reason for its collapse. Under certain conditions a particular SN, known as a Type Ia, occurs when a star 'steals' additional mass from a companion star. Due to the physical properties of this accretion, Type Ia SNe all have the same mass at collapse and hence the same absolute luminosity.  Astronomers can measure the SN's apparent luminosity and thereby calculate its distance. By comparing this information to the observed redshift, cosmologists can use the measurements to constrain their geometric models for the universe and to estimate various free parameters that exist under general relativity.  

The electromagnetic spectrum of SNe can be recorded via spectroscopy.  Given this information, near perfect classification of SNe has been achieved.  With modern photometric surveys, however, many orders of magnitude more SNe are observed than can be confirmed spectroscopically. A related technique, known as photometry, measures only a few slices of the electromagnetic spectrum.  This is much less resource intensive and hence it is possible to record the photometric information for every observable SN.  However, the substantial information loss, as well as induced cosmological considerations, make photometric SN classification a challenging, open problem.

In this talk, we give an overview of why Type Ia SN are so important for modern cosmology, the cosmological complications of making photometric measurements, and the techniques that have been developed for the photometric classification of SN.