Type Ia supernovae: do we understand our fundamental cosmological probes?


Supernovae are the extremely luminous explosions of stars at the end of their lives. The use of a particular type of exploding star, Type Ia supernovae, as probes of cosmology is now well established; the 2011 Nobel Prize in Physics was awarded for the discovery using Type Ia supernovae of the accelerating Universe and mysterious quantity, 'dark energy'. Dark energy makes up greater than 70% of the mass-energy of the Universe but its origin is still unknown. Next-generation transient surveys such as the Large Synoptic Survey Telescope (LSST) will discover a million SNe Ia, many many times more than currently known, with the aim of better constraining the properties of dark energy.

Despite the great success of Type Ia supernovae as cosmological distance indicators, embarrassingly little is known about the underlying stellar systems that explode as Type Ia supernovae. It appears that the star that explodes is a small dense star called a white dwarf but how the explosion is triggered, and what its companion star is, remain a mystery. Recent transients surveys have also discovered unexpected and strange events that appear to be associated with the explosions of white dwarfs but have peculiar properties. The aim of these projects is to constrain the systems that explode as Type Ia supernovae and their diversity, which is vital for improving their use as cosmological distance indicators in upcoming transient surveys.


1) Connecting Type Ia supernova observations to their explosion mechanisms

The project will use data from some of the world's largest telescopes such as ESO's Very Large Telescope in Chile, as well as from state-of-the-art transient surveys. The project will involve analysing optical and near-infrared of Type Ia supernovae and their host galaxies, and comparison with the latest Type Ia supernova spectral modelling to determine their explosion parameters such as explosion energy, mass of radioactive material produced, and possible explosion asymmetries. This study will investigate the controversial result that Type Ia supernovae may be produced through more than one explosion channel, which may have implications for future Type Ia supernova cosmology studies.

2) Constraining the extremes of white dwarf explosions

Recent state-of-the-art transients surveys have uncovered a much wider-than-expected range in Type Ia supernova explosions. Some of these supernovae evolve much faster than standard Type Ia supernovae, and have unusual spectral properties. New theories have been put forward to explain them, such as a detonation on the surface of a white dwarf but a clear link between their observed properties and these theories has not yet been determined. The project will involve analysing data from leading transient follow-up surveys (e.g. PESSTO), combined with detailed follow-up observations to constrain the zoo of transients that has been discovered and link them to specific explosion mechanisms.


The large supernova group at Queen's provides an active, lively, and stimulating research environment. The student will have the opportunity to travel for conferences/workshops, as well as for international collaborative visits and meetings. At least one observing trip to a telescope abroad (e.g. Canary Islands, Chile) is envisaged to gain experience in observations, data analysis, and transient classification.

More info

Supervisor: For further information, please contact Dr Kate Maguire.

public/phds2017/2017_maguire.txt · Last modified: 2016/12/09 22:35 by Stuart Sim

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