Artists’s impression of a Type Ia supernova / ESA/ATG medialab/C. Carreau
The extreme Universe Stars end their lives in extraordinary ways. Stars like the Sun end up as hot dense cores. Larger stars explode as supernovae, and their remnants are ultra-dense neutron stars. Even larger stars end their lives as black holes, after an immense cataclysm which generates gamma-rays detectable from the furthest reaches of the cosmos. MSSL investigates neutron stars and gamma-ray bursts using facilities in X-rays and the ultraviolet/optical – mostly instruments we’ve built for ESA’s XMM-Newton (X-ray Multi-Mirror Mission) and NASA’s Swift satellites. We are particularly interested in highly-magnetised neutron stars called magnetars, which emit spectacular outbursts of soft-gamma-rays, and in young hot neutron stars still cooling after their supernova. We use these objects to examine the physics of ultra-dense matter, and the extraordinary interaction of radiation and matter in the most extreme magnetic fields in the Universe. The novel technique of X-ray polarimetry is one of our current interests, as is the nature of the fireball resulting from the formation of the black hole, and whether there is a continuum of characteristics between supernovae and gamma-ray bursts. At the centres of at least most galaxies there are even larger black holes, millions of times more massive than those formed in stellar explosions. They lie at the focal point of the galaxy’s gravitational field, growing by taking in gas, stars, and stellar remnants. The strong gravity of these large but extremely dense objects shapes the space around them. The path that light takes is no longer straight, and as seen from a distant observer, the scene about them is distorted and multiplied. We calculate these effects, including absorption and scattering by intervening material in disks and clouds, to predict their signatures in our observations, and hence to arrive at the nature of the environments of black holes.
What happens to stars at the end of their lives? How does light travel near a black hole? What is the environment of black holes in active galaxies?
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