Institute of Astronomy

A fresh check on supernova cosmology

Published on 06/07/2015 

A team from the University of Cambridge has used the largest sample of supernovae and host galaxies to date to study the relation between host galaxy and the precise brightness of the supernova.

The amount of dark energy in the Universe is a matter of debate. The first evidence for dark energy – an energy field causing the expansion of the Universe to accelerate – came through measurements of Type Ia supernovae, which are used by astronomers as cosmic lighthouses to determine distances. However, there is now increasing evidence that Type Ia supernovae are not ‘standard candles’ and the precise brightness reached by these exploding white dwarf stars depends on the environment in the host galaxy.  Now, Dr Heather Campbell and colleagues at the University of Cambridge have used the largest sample of supernovae and host galaxies to date to study the relation between host galaxy and supernova luminosity.

On Tuesday 7th July, a special session at the National Astronomy Meeting (NAM) 2015 has been convened for astronomers to take stock of the evidence and stimulate further investigation of cosmology.

“Understanding the effect of the properties of the host galaxy is critical if astronomers are to make the most precise measurements possible of dark energy,” said Campbell.  “More massive galaxies tend to have fainter supernovae.  If the galaxy properties are not accounted for properly, then the amount of dark energy in the Universe is underestimated. This work is crucial for future telescopes and space missions such as LSST and Euclid, which will attempt to make precision measurements of the expansion of the Universe.”

The session convener, Prof Peter Coles said, “Although cosmology has made great progress in recent years, many questions remain unanswered and indeed many questions unasked. This meeting is a timely opportunity to look at some of the gaps in our current understanding and some of the ideas that are being put forward for how those gaps might be filled.”

IoA Science contact: Dr Heather Campbell  hcc@ast.cam.ac.uk

Figure caption: Type Ia supernovae, such as supernova 1994D in galaxy NGC 4526 (imaged here by the Hubble Space Telescope), are used as cosmic lighthouses by astronomers to measure distance in the Universe.  Credit: NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team 

Page last updated: 7 July 2015 at 09:25