Gamma-Ray-Burst studies have rapidly become one of the hot frontiers in
astrophysical research, thanks to the BeppoSAX italian satellite. This
mission, managed by the IASF in Rome together with Bologna and Palermo
sections, has been launched in 1996 and successfully concluded in 2002,
with a wealth of bursts data. It opened an entirely new research chapter:
the physics of afterglows, lower energy residual emissions of these cosmic
explosions, whose analysis led to the epochal discovery of their
extragalactic origin. IASF team won in 1998 the Bruno Rossi Prize for High
Energy Astrophysics, for its fundamental contribution to the discovery of
this emission, a key in unveiling the mistery of lacking GRBs optical
counterparts. Furthermore, in 2002, the European Community awarded the
Descartes Prize to BeppoSAX scientists, confirming their leadership in
bursts studies.
But what are the engines of these outstanding phenomena? And what about
their cosmological implications?
The discovery of iron lines in Gamma-Ray-Bursts by IASF researchers using
BeppoSAX and Chandra data, shows that the progenitors of such events are
super-massive bodies exploding in star-forming regions of remote galaxies,
while the capability to measure the redshift directly by X-ray
measurements, will clarify the "remaining mysteries": dark GRBs (i.e. those
without optical counterparts) and X-ray rich GRBs (i.e. GRBs whose
luminosity is peaked in the X rather than the Gamma-ray range), classes of
objects whose distance is still to be determined. Some of these events
could be related to GRBs at z>5-10, opening therefore the perspective of
probing the early Universe.
Source spectroscopy in the X band is an extremely efficient technique,
allowing an accurate diagnostic of burst environment and approaching the
central engine by means of a more penetrating radiation than radio emission
or optical light. In fact, the simulations show well detectable lines from
the interaction between photons and the GRB cradle.
The extraordinary cosmological interest of these observations is clear:
gamma bursts could be used as efficient probes of the primordial Universe
(z>3), allowing to understand the evolution of star formation and to trace
extra-galactic matter distribution inside and outside the hosts, up to
distances never reached before.
This scientific objectives require a new generation of instruments and IASF
researchers are at the forefront of project teams working in that field.
While exploiting present data (Integral), or preparing Swift and AGILE,
able to provide continuous burst positioning and high energy information,
they are projecting state-of-the-art experiments like IMBOSS, an high
resolution spectrometer that should be mounted on the International Spatial
Station, aimed to survey the sky in search of prompt GRB X-ray
counterparts, and XEUS, an ESA observatory with enormous concentrators and
a 30 m2 detector, 250 times more sensitive than XMM-Newton.
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