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Licentiate Thesis: Detecting circumstellar dust surrounding type Ia supernovae and its implications on cosmology
  Various tests 1

Monday 13 June 2016
from 10:15 to 12:15
at FB51
Speaker : Raphael Ferretti (Stockholm University, Department of Physics)
Abstract : Type Ia supernovae have been of great value to our understanding of cosmology. With the use of supernovae, the accelerating expansion of the universe was first discovered and they are to date of great importance in constraining cosmological parameters. Today the accuracy at which one can determine cosmological parameters with supernovae is no longer limited by small sample numbers, but rather systematic errors in our understanding of the explosions. One such systematic error is the effect dust has on the observed supernovae. In particular, peculiar extinction laws due to dust have recently become apparent. A possible explanation to the unusual extinction laws would be the presence of circumstellar dust. Among other methods to search for circumstellar matter around type Ia supernovae, is the analysis of highresolution spectra. Gas in the vicinity of supernovae is expected to be ionised by early ultraviolet radiation, which should cause narrow absorption lines to change detectably. Today a small number of supernovae with varying sodium D absorption have been found, but no cases can be conclusively attributed to photoionisation. Furthermore, recent results show that most time-series of high-resolution spectra do not cover the relevant time frame during which photoionisation is expected to occur. Future observation must aim at obtaining earlier spectra to test for circumstellar matter.

Nordita  | Last modified 13 June 2016 13:02  |  HELP