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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.
Selected Publications
MNRAS = Monthly Notices of the Royal Astronomical Society
ApJ= Astrophysical Journal
ApJL = Astrophysical Journal Letters
AJ = Astronomical Journal
Suzaku wide-band X-ray spectroscopy of the Seyfert 2
AGN in NGC4945, Itoh, T.,
Griffiths, R.E., et al., PASJ (Second
Suzaku Special Issue), in press. (2007)
Revealing the High Energy Emission from the Obscured
Seyfert 1.9 Galaxy MCG-5-23-16 with Suzaku, Reeves, J.,
Griffiths, R.E.,
,
PASJ, 59, S283. (2007)
Requirements on Extremely Large Telescopes from the
perspective of X-ray astronomy, Griffiths, R.E., 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)
Beyond the Limits of Deep X-ray Surveys: Galaxies of
AGN ?, Griffiths, R.E., Miyaji, T., Knudson, A. & Schurch, M., 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)
Prospects and requirements for Measurements of
Extragalacticg ray lines,
Griffiths, R.E., in Focusing Telescopes in Nuclear Astrophysics,
reprinted from Experimental Astronomy, Vol. 20, Nos. 1-3, Proc.
Gamma-Wave 05, Springer, pp. 23-30. (2006)
The Dark Universe Observatory, Griffiths, R.E.,
Petre, P., Hasinger, G., Predehl, P., White, N.E., Aschenbach, B, Barcons, B.,
et al., SPIE, 5488, 209. (2004)
Iron K-a
Emission frm the Low Luminosity Active Calaxies M81 and NGC4579, Dewangan,
G.C., Griffiths, R.E., DiMatteo, T., Schurch, N.J., ApJ, 607,
788. (2004)
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