Emeritus Professor, Physics
EducationPh.D., University of Leicester, England
Griffiths' research programs are in space astronomy, especially 'deep surveys' using current earth-orbiting optical and X-ray telescopes, part of the work of observational cosmology. In a 'deep survey' a telescope is pointed at a blank region of sky for about a week, in order to find the faintest and most distant objects that the telescope can detect.
He is currently involved in the results of deep X-ray surveys using the two large X-ray telescopes launched in 1999, the Chandra X-ray Observatory, CXO (NASA) and the XMM-Newton satellite (European Space Agency). He is a Co-Investigator and member of the Science Team for the CCD camera on CXO, and a member of the Science Working Group for XMM-Newton. Griffiths works on the origin of the X-ray background from space, using the deep images taken with these earth-orbiting X-ray telescopes. He has found that the X-ray background has its origin in quasars and other active galactic nuclei, and some of it originates in starburst galaxies. With images from these satellites, he uses some of the world's largest telescopes to identify the kinds of galaxies which are the greatest producers of X-rays.
Griffiths has also led the Medium Deep Survey, a Key Project using the Hubble Space Telescope, and the largest program of observations ever undertaken with the Hubble. This survey used the Wide Field Camera in serendipitous mode, taking pictures of random, unknown areas of sky while the telescope was simultaneously collecting data from known targets using other instruments. The images of tens of thousands of galaxies have been used to unravel the origin and evolution of galaxies, from giants like the Milky Way to the much more numerous dwarf galaxies. He has been putting constraints on cosmological parameters, as well as measuring the evolution of different galaxy types. With his research group, he is also finding strong gravitational lenses, and measuring the frequency of galaxy mergers.
- T. Itoh et al., Suzaku wide-band X-ray spectroscopy of the Seyfert 2 AGN in NGC4945, Publ. Astron. Soc. Japan (Second Suzaku Special Issue), [arXiv:0708.1201].
- Yaqoob, T. et al., Precision Fe Kα and Fe Kβ Line Spectroscopy of the Seyfert 1.9 NGC 2992 with Suzaku, Publ. Astron. Soc. Japan 59, S283 (2007).
- R. E. Griffiths, Requirements on Extremely Large Telescopes from the perspective of X-ray astronomy, in Proc. IAU Symposium 232, The Scientific Requirements for Extremely Large Telescopes, eds. Whitelock, P.A., Dennefeld, M., & Leibundgut, B., Cambridge University Press, p. 209 (2006).
- R. E. Griffiths, T. Miyaji, A. Knudson, and M. Schurch, Beyond the Limits of Deep X-ray Surveys: Galaxies of AGN?, in Proc. IAU Symposium 230, Populations of High Energy Sources in Galaxies, eds, Meurs, E.J.A. & Fabbiano, G., Cambridge University Press, p. 438 (2006).
- R. E. Griffiths, Prospects and requirements for Measurements of Extragalactic g–ray lines, in Focusing Telescopes in Nuclear Astrophysics, reprinted from Experimental Astronomy, Vol. 20, Nos. 1-3, Proc. Gamma-Wave ’05, Springer, pp. 23-30 (2006).
- R. E. Griffiths et al., The Dark Universe Observatory, SPIE 5488, 209 (2004).
- G. C. Dewangan, R. E. Griffiths, T. DiMatteo, and N. J. Schurch, Iron K-α Emission from the Low Luminosity Active Galaxies M81 and NGC 4579, Astrophys. J. 607, 788 (2004).