A rolling grant for the observation and study of cosmic X-ray sources (Apr 2009 to Mar 2014)
Lead Research Organisation:
University of Cambridge
Department Name: Institute of Astronomy
Abstract
The X-ray Group at the Institute of Astronomy has analysed and interpreted data from most cosmic X-ray telescopes and instruments. This grant application is to renew the rolling grant for its support. Over the next five years we shall pursue a programme of research centred on accreting black holes and clusters of galaxies. The most luminous non-explosive sources in the Universe are active galaxies and quasars, which are powered by an accreting black hole. Most of the X-ray emission from these objects originates close to the black hole where gravity is very strong. This causes high velocities and large redshifts, both doppler and gravitational, as well as strong bending of light. The emission spectrum from matter at the innermost radii is consequently highly distorted in a manner first discovered by us and which is easily recognised. We propose to measure these relativistic distortion using both the X-ray spectrum and its variability. The results can then be used to determine the geometry of the accretion flow and the source of the X-ray continuum. Through the location of the innermost orbit, we shall measure the spin of the black hole. The energy produced by a central massive black hole can have a profound effect on its host galaxy. This can be vividly observed when the galaxy is at the centre of a group or cluster of galaxies and the energy is emitted through jets. X-ray images show bubbles filled with relativitic plasma inflating and rising through the surrounding gas. Concentric ripples show energy flowing away from the bubbles in giant sound waves discovered by us and which dissipate heating the surrounding gas. The energy transferred in this way stops much of the gas from cooling rapidly and forming massive amounts of new stars. Filaments of cold gas are dragged around by the bubbles so marking the velocity field of the cluster core. We shall analyse and interpret X-ray and longer wavelength observations of the cores of groups and clusters in order to understand this important galaxy feedback process, including how and when a heating/cooling balance is established, how much cooling and star formation takes place and how much it applies to the formation of all massive galaxies. Funding for Postdoctoral Research Assistants to work on these exciting and fundamental topics in astrophysics is sought for a five year programme.
Organisations
Publications
Bautz M
(2009)
Suzaku Observations of Abell 1795: Cluster Emission to r 200
in Publications of the Astronomical Society of Japan
Cackett E
(2010)
CONTINUED COOLING OF THE CRUST IN THE NEUTRON STAR LOW-MASS X-RAY BINARY KS 1731-260
in The Astrophysical Journal
Cackett E
(2010)
QUIESCENT X-RAY EMISSION FROM Cen X-4: A VARIABLE THERMAL COMPONENT
in The Astrophysical Journal
Cackett E
(2011)
Quiescent X-ray variability from the neutron star transient Aql X-1 Quiescent variability from Aql X-1
in Monthly Notices of the Royal Astronomical Society
Cackett E
(2010)
RELATIVISTIC LINES AND REFLECTION FROM THE INNER ACCRETION DISKS AROUND NEUTRON STARS
in The Astrophysical Journal
Canning R
(2011)
Detection of optical coronal emission from 106-K gas in the core of the Centaurus cluster Coronal line emission in NGC 4696
in Monthly Notices of the Royal Astronomical Society
Canning R
(2011)
A deep spectroscopic study of the filamentary nebulosity in NGC 4696, the brightest cluster galaxy in the Centaurus cluster The filaments of NGC 4696
in Monthly Notices of the Royal Astronomical Society
Canning R
(2010)
Star formation in the outer filaments of NGC 1275 Star formation in NGC 1275
in Monthly Notices of the Royal Astronomical Society
Degenaar N
(2011)
Further X-ray observations of EXO 0748-676 in quiescence: evidence for a cooling neutron star crust Neutron star crust cooling in EXO 0748-676
in Monthly Notices of the Royal Astronomical Society
Edge A
(2010)
Herschel photometry of brightest cluster galaxies in cooling flow clusters
in Astronomy and Astrophysics