X-ray astronomy

The Birmingham Extragalactic Group studies a wide range of cosmic structures, from star clusters to superclusters, using a combination of multi-wavelength observations (radio, IR, optical and X-ray), advanced analysis techniques, and hydrodynamical modelling. A common requirement in astronomy is extraction of physical information (i.e. kinematics, stellar population ages, or temperature of hot gas) from spectra or spectral images of astronomical objects. As a part of the AstroGrid project, the School of Physics and Astronomy and the School of Computer Science have developed a new technique which is capable of mapping of physical characteristics for large samples of objects, such as, galaxies and regions of the solar surface. The figure below shows a map of the temperature distribution of the hot gas in the core of the galaxy group HCG 62, which lies at a distance of 200 million light years from Earth. This map is produced by hyperspectral imaging applied to the X-ray emission detected by the Chandra X-ray observatory. The temperature scale down the right hand side runs from 7 million (blue) to 17 million (red) degrees Kelvin.

Many galaxies, like our own Milky Way, are found in groups. Galaxy groups contain large amounts of dark matter and their strong gravitational fields compress the intergalactic gas to temperatures of many millions of degrees. This gas then radiates X-rays and, in the innermost regions of groups, such as the 300,000 light year diameter region imaged here, the loss of energy in X-rays is sufficient to significantly cool the gas. This accounts for the cool (blue) blobs visible in the image. This cooling gas may feed a supermassive black hole in the central galaxy of the group.

The Chandra X-ray observatory, from which these data were taken, is one of the world's two largest orbiting X-ray telescopes, launched by NASA in December 1998. It is the first X-ray instrument able to produce images with comparable resolution to good optical telescopes. Time on this valuable facility is awarded on the basis of strict peer review, and scientists at Birmingham have been very successful in the annual competitive process by which these allocations are made.


Professor Trevor Ponman
Email: tjp@star.sr.bham.ac.uk
Tel: 0121 414 6448


Dr Somak Raychaudhury, School of Physics and Astronomy
Email: somak@star.sr.bham.ac.uk
Tel: 0121 414 6474