1. Binaries Containing Compact Objects

• The theory of low- and intermediate-mass X-ray binaries (LMXBs/IMXBs) and their relation to millisecond pulsars .
  

• Recent studies have shown that the majority of LMXBs may in fact be descendants of IMXBs and that the standard model is wholly inappropriate.

• Possible solution: irradiation-driven mass-transfer cycles: requires the modelling of irradiated secondaries (Sam Phillips) and in particular of the irradiation-driven circulation (Martin Beer).

• The evolution of black-hole binaries (e.g. Nova Sco, GRS 1915+105).

• The origin of ultracompact binaries, binaries with periods as short as 11 min (e.g. X1820-303, AM CVn binaries).

• Collaborators: Saul Rappaport (M.I.T.), Eric Pfahl (CfA, Harvard), Rosemary Mardling (Monash)

2.  Supernovae in Binaries

• Modelling the evolution of the progenitors of core-collapse supernovae (i.e. the explosion of massive stars), in particular SN 1987A and SN 1993J (SN 2000cl).

• SN 1987A was the first naked-eye supernova since Kepler's Supernova in 1604 and is most likely the result of the merger of two massive stars inside a common envelope (press release).

• Hydrodynamical modelling of the formation of the triple-ring nebula around SN 1987A (Thomas Morris).
  

• Modelling the slow merger of massive stars using stellar structure and 2-/3-dimensional hydrodynamical simulations (Natasha Ivanova [Northwestern]).

3. Type Ia Supernovae

• Type Ia supernovae, the thermonuclear explosions of a massive white dwarf leading to its complete disruption, have been used in recent years to measure the acceleration of the Universe.

• However, the nature of their progenitors has remained a major unsolved problem.

• Study progenitor models and the presupernova structure (Pierre Lesaffre).

• Model their population using binary population synthesis (Zhanwen Han [Kunming]).

• Member of the European Research and Training Network "The Physics of Type Ia Supernovae".  

• Other collaborators: Brian Schmidt (Mount Stromlo), Paolo Mazzali (Trieste), S. Ch. Yoon (Utrecht), Norbert Langer (Utrecht)
  

4. Gamma-Ray Bursts (GRBs) and Hypernovae

• Gamma-ray bursts are short flashes of mainly gamma-rays, lasting from a fraction of a second to tens of minutes.

• The identification of optical counterparts in 1998 has shown that they may be the most energetic events in the Universe, visible throughout the whole Universe.

• Some GRBs are now known to be associated with hypernovae, very energetic supernovae, possibly caused by the collapse of a massive helium core into a black hole.

• Study possible progenitor models for both hypernovae and GRBs and understand their implications for galaxy formation (with Joe Silk).

• Collaborators: Enrico Ramirez-Ruiz (Princeton), Martin Rees (Cambridge), Ken Nomoto (Tokyo), Paolo Mazzali (Trieste)
  

List of abstracts and published papers

Homepage