Our research covers a broad range of topics in supernova and extra-galactic explosive transient research. In particular, it focusses on the following topics:
- Unveiling the properties of electromagnetic counterparts to gravitational waves
- Understanding the progenitor systems of Type Ia supernovae
- The use of supernovae as cosmological distance indicators
- Exploring the extremes of supernova explosions
Electromagnetic counterparts to gravitational waves:
In August 2017, the era of multimessenger astronomy began with the detection of an astrophysical source via both gravitational waves and photons. This offers a new way to study the Universe. On 17 August 2017, for the first time, we both heard (via gravitational waves from the LIGO/VIRGO detector) and saw (via electromagnetic radiation) the merger of two neutron stars in the distant Universe (e.g. Smartt et al. 2017). Through detailed measurements of its properties, we determined that neutron star mergers are key site of r-process nucleosynthesis in the Universe. The 'Electromagnetic Counterparts of Gravitational Wave sources at the Very Large Telescope' ENGRAVE collaboration is the leading European effort (with ~200 members) for gravitational wave follow-up of gravitational wave triggers.
Type Ia supernovae: from explosions to cosmology:
Type Ia supernovae are the incredibly luminous deaths of white dwarfs in binary systems. They play a vital role in chemical enrichment, galaxy feedback, stellar evolution, and were instrumental in the discovery of dark energy. However, what are the progenitor systems of SNe Ia, and how they explode remains a mystery. My ERC starting grant, SUPERSTARS, aims to obtain novel early-time observations (within hours of explosion) of 100 SNe Ia in a volume-limited search (75 Mpc). The targets will come from high-cadence searches, such as ATLAS and ZTF, and the new search facility, BlackGEM, that will provide unprecedented sky coverage and cadence. These data will be combined with key progenitor diagnostics of each supernova (companion interaction, circumstellar material, central density studies). The observed zoo of transients predicted to result from white-dwarf explosions (He- shell explosions, tidal-disruption events, violent mergers) will also be investigated, with the goal of constraining the mechanisms by which white dwarfs can explode. For this project, we use data from the (e)PESSTO(+) survey, which has been in operation since 2012, which operates at New Technology Telescope at La Silla.
Unexpected rapidly-evolving transients:
The revolutionary $800 million dollar experiment, the Large Synoptic Survey Telescope (LSST), will begin operations in the early 2020s. It will discover an order of magnitude more transients than previously possible and explore the extremes of the transient sky. In particular, it will discover fast-evolving transients that were discovered in only low numbers by previous surveys. Our aim is to find these rare and rapidly-evolving transients as soon as possible after explosion so we can constrain how and why they explode. Unusual objects such as AT2018cow (Prentice, Maguire, et al. 2018) are pushing the boundaries of the currently available stellar explosion models. Theories to explain these objects include circumstellar interaction, magnetar spin down, or the tidal disruption from an intermediate massive black hole but their origin is still unknown.
The bottleneck for science returns from LSST will be spectroscopic classification and follow-up, which is why we have formed the Time-Domain Extragalactic Survey (TiDES) within the 4MOST consortium. The aim of TIDES is to use the multiplex capabilities of 4MOST to trigger rapid follow-up of interesting fast-evolving transient events, combined with static host galaxy studies for Type Ia supernova cosmology.