Time domain astronomy

Time domain astronomy explores distant sources whose brightness varies with time. This includes transient events that appear and fade over the course of seconds, hours, days or even years, as well as persistent but variable sources of ever-fluctuating luminosity. When we look up at the night sky and see the same stars night-to-night, it's easy to think of the Universe as static and constant. However, look deep enough and you'll see an alive and dynamic cosmos of energetic and often explosive processes. In Birmingham we study transient events to understand physics under extreme conditions, including the physics of gamma-ray bursts and tidal disruption events.

Our team

Academics: Dr Clément BonnerotDr Ben Gompertz
Students: Simona Pacuraru, Evan Ridley, Isabelle Worssam

Distant starsCredits: International Gemini Observatory / NOIRLab / NSF / AURA / M. Zamani

Time domain astronomy at Birmingham

Gamma-ray Bursts (GRBs) are some of the most energetic explosive transients in the Universe. They come from powerful jets of material travelling at almost the speed of light, driven by collapsing massive stars and merging neutron stars. By studying their powerful emission, we can learn how relativistic jets are launched and subsequently punch their way through their local environments.

GRBs act as cosmic lighthouses for where and when stars formed and died, and provide insights into how often the dead cores of stars collide to produce the heaviest elements in the Universe. Our work probes the diversity of jets launched by neutron star mergers, aiming to investigate what the binary was made of and what survived the collision. We also observe and model the accompanying kilonovae - the radioactive glow of heavy element creation - to understand the yields and abundance patterns produced by the merger.

Tidal disruption events (TDEs) happen when an unlucky star is torn apart by the strong tidal forces of a supermassive black hole. Following this disruption, the gas stripped from the star gets accreted onto the black hole, leading to the emission of a powerful flare of radiation.

This signal represents a powerful probe of supermassive black holes lying in otherwise quiescent galaxies, which can be used to infer the properties of these compact objects and put constraints on their unknown formation mechanism. By means of analytical calculations and simulations, we aim at theoretically characterizing the radiation emitted from TDEs that our telescopes can detect. This robust physical model will allow us to optimally exploit future observational data to learn about supermassive black holes and the extreme processes taking place in their vicinity.