22 March 2005
22 March 2005
Speaker: Rashid Sunyaev (Max Planck Institut fur Astrophysik; Sackler Lecture)
The Sky in Hard X-Rays
The first year of INTEGRAL observations has given several
A)The population of heavily obscured x ray sources was discovered
in our Galaxy. It is analogous to the population of heavily obscured AGNs.
B) The all sky observations of hard x ray sources continue.
The first results gave a sample of low redshift sources which
is significantly more abundant than observed in previous all
sky surveys in the 20 60 keV spectrum band.
C) Hard x ray emission is detected from several giant molecular
clouds, but the SGR B2 cloud has the highest luminosity among them
and has an unusually hard power law spectrum extended at least up
to 150 keV. Together with ASCA, SAX and CHANDRA results, these
observations prove that the observed x ray flux from SGR B2
results from the reflection of emission from SGR A* in the
natural Compton mirror. This observation proves that the SGR
A* black hole 400 years ago was a million times brighter in x
rays than today and had an x ray spectrum typical for AGNs.
D) The discovery of a gamma ray burst with luminosity orders
of magnitude smaller than that of cosmological gamma ray bursts.
Such intrinsically sub energetic events may occur very frequently
in the Universe.
E) Fine spectroscopy of the central part of the Galaxy in electron
positron annihiliation line and properties of the interstellar
matter where annihilation occurs.
F) The main problems and future of the field.
Video of the Presentation:
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