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Supervisors: Dr P T O'Brien, Dr D J Raine, Dr M J L Turner, Professor M J Ward, Dr R S Warwick.
Active Galactic Nuclei (AGN) and Quasi-Stellar Objects (QSOs) together form the large population of objects known as active galaxies. Active galaxies are the most powerful objects in the Universe, spanning a huge range in luminosity, from dwarf AGN - less powerful than the brightest stellar-systems - up to the most luminous QSOs which are a million times brighter than the Milky Way. It is generally accepted that active galaxies are primarily powered by the accretion of matter onto a central, supermassive black hole.
Active galaxies emit at all wavelengths, and can display a wide range of phenomena. These include: powerful radio-jets; infrared emission from both cool and hot dust; strong, highly-variable ionizing-continuum emission; broad and narrow emission-lines covering a large range in ionization; and broad-band X-ray and gamma-ray emission. To study these phenomena, the observational programme at Leicester makes extensive use of multi-wavelength ground- and space-based observational facilities, several of which include instrumentation built at Leicester. Our spectroscopic and imaging data are compared to detailed theoretical models developed at Leicester which predict the characteristics of the accretion flow, the emission-line spectrum and the effect of absorbing material thought to exist close to the nucleus. These active galaxy models draw on those developed at Leicester for stellar black-hole systems, providing a probe of black-hole physics across the entire known mass-spectrum of these extraordinary objects.
For more information please see the AGN entry in the XRA Group biannual report.
See also the posters entitled "X-ray properties of Narrow-line Seyfert 1s" and "PDS 456: an extreme accretion rate quasar?", available on our posters page.
Contact: Paul O'Brien (pto@star.le.ac.uk)
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