Rees Williams

INTEGRAL

My research interests are in the X-ray and gamma-ray emission from
high luminosity AGN.

I started in this field of research almost 20 years ago when I
developed the X-ray analysis and archive system used for Ginga
data in Leicester.  Ginga was a very good instrument for studying
AGN. In the Ginga quasar survey I was the first person to show the
steeper continuum in radio-quiet quasars c.f. blazars. I also
showed that the spectra of the radio-quiet quasars was similar to
that of Seyfert 1 galaxies i.e. it could be explained by the
reprocessing of emission by material outside the central emission
region.

I then spent 10 years working on the analysis and archiving of
COMPTEL data. COMPTEL analysis was even more complex than that of
INTEGRAL. We detected only ten AGN with COMPTEL:  Cen A and 9
blazars. In many ways the most significant results I published
were negative: in particular we detected no Seyfert galaxies. At
the time this was a surprise as MeV emission had been claimed from
4 Seyferts prior to COMPTEL. I also showed that the sharp peaks in
emission claimed in some blazars were not in fact statistically
significant.

Currently, I spend very little of my time on research. I'm still 
interested in comparing the hard X-ray emission from radio-quiet
quasars with that from Seyfert galaxies. One of the best quasars
for such a study is PG1416-129 which has a very flat spectrum
making it by the highest luminosity radio quiet AGN detected by
INTEGRAL.