Event Details

Measuring the expansion history of the Universe with Supernovae Type Ia: successes and pitfalls

  • 2017-02-13
  • Prof. R. Trotta, Imperial College London

Supernovae type Ia (SNIa) are one of the observational pillars of the concordance cosmological model, and have been instrumental in determining the existence of dark energy. While the observational effort has been very successful in finding over 1,000 cosmologically useful SNIas, the sophistication of statistical methods employed to analyse the data and infer cosmological parameters has been lagging behind.
I will present an overview of the status of SNIa cosmology, as well as new results from BAHAMAS (BAyesian HierArchical Modeling for the Analysis of Supernova cosmology), a fully Bayesian analysis of SNIa data, a demonstrably superior approach which improves on many shortcomings of the usual method. I will discuss how environmental effects in the SNIas host galaxies must be taken into account in order to reduce systematic errors and to exploit upcoming large SNIas data sets. I will present recent findings suggesting that the distance of the SNIas to their host galaxy can be used to improve their usage as standard candles.

Roberto Trotta is a theoretical cosmologist at Imperial College London, where he studies dark matter, dark energy and the Big Bang, and an STFC Public Engagement Fellow. Roberto was born and grew up in the Italian speaking part of Switzerland. After obtaining an MSc(hons) in Physics from ETH Zurich and a PhD in Theoretical Physics from the University of Geneva, he moved to Oxford where he was the Lockyer Fellow of the Royal Astronomical Society at Oxford University, and a Junior Fellow of St Annes, before being appointed at Imperial in 2008.
Roberto is the recipient of numerous awards for his research, teaching and science communication activities, including the Lord Kelvin Award of the British Association for the Advancement of Science, the Michelson Prize of Case Western Reserve University and an Imperial College Presidents Award for Excellence in Teaching.
His award-winning first book for the public, The Edge of the Sky: All you need to know about the All-There-Is, endeavours to explain the Universe using only the most common 1,000 words in English. Roberto was named as one of the 100 Global Thinkers 2014 by Foreign Policy magazine (Nov 2014), for junking astronomy jargon.​