Supernova Remnants

nova.jpgSNRs are a key, visible link in the cycle that produces the heavy elements; stellar birth, nuclear burning in the stellar core, stellar death - a supernova explosion, supernova remnant, dispersal of material into the interstellar medium, stellar birth...

Remnants can be observed across the electromagnetic spectrum from radio through to gamma rays with each waveband providing vital information about the nature of the progenitor, the dynamics of the explosion, shock physics and the dissipation of energy and matter into the interstellar medium. We concentrate on the analysis of X-ray observations of relatively young SNR for which we have both spatial and spectral information. Careful study of the X-ray spectra over the face of the remnant can provide a unique glimpse at the state and composition of the plasma and the physics of the interaction between the ejecta from the initial explosion and the surrounding interstellar medium. If we have good statistics and energy resolution (CCD energy resolution or better as we have from XMM-Newton and Chandra), the doppler shift of the X-ray lines can be measured thereby giving us a dynamical picture of the expanding medium.

In 1979 we were members of the team from MIT and Leicester that made the first X-ray images of a SNR, Cygnus loop, using a sounding rocket payload. In the following years we analysed images of Puppis A, Cygnus Loop, SN1006, W44, IC443, W49B and Cas A using data from the Einstein Observatory. Our recent analysis has concentrated on data from XMM-Newton, in particular Cas A and the Crab Nebula and currently both XMM-Newton and Chandra are producing data from SNR which are very challenging to analyse and interpret; our picture of SNR is getting more and more complicated.

In 2003 it was estabished that at least some Gamma Ray Bursts are directly associated with Supernova explosions. Our longstanding expertise in SNR has therefore become intermeshed with recent interest and research into GRBs using the unique, Gamma Ray, X-ray and optical data that is being taken by Swift.

 

 

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The X-ray spectrum of Cas A as observed by XMM-Newton. Careful modelling can be used to measure the ionisation state of the plasma over the face of the SNR. We can also extract the Doppler shift of the elemental spectral lines and construct velocity maps of the expansion as seen in different elements. This gives us vital clues about how the layers of stellar core material from the progenitor are ejected by the supernova explosion to form the remnant that we see.

 

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