Speaker
Peter Garnavich
(University of Notre Dame)
Description
Type Ia supernovae are believed to be thermonuclear explosions of carbon-oxygen
white dwarf stars. Observationally they show a wide range of light curve shapes and
peak luminosities at optical wavelengths. Fortunately their peak brightness
correlates with the decline rate of their light curve making them "standardizable"
candles with a precision of 7 to 10% in distance. At near infrared wavelengths,
type Ia supernovae appear to be closer to true standard candles and also less
susceptible to dust extinction. Observations between 1 and 3 microns may be the
ideal way to use type Ia supernovae as accurate cosmological probes. The origin of
the diversity in type Ia supernovae remains an interesting problem. The peak
brightness is controlled by the mass of radioactive nickel produced in the
explosion, but what determines the nickel yield? Possibilities include the heavy
metal content of the progenitor star or the mass of the star that produced the
white dwarf. Both possibilities are examined by studying the characteristics of the
galaxies that host type Ia events.
Author
Peter Garnavich
(University of Notre Dame)
