Celebrating a mature high-energy astrophysics mission
In the beautiful resort of Chia Laguna, Sardinia (Italy) about 130
scientists celebrated five years of successful observations with
INTEGRAL and the new lessons learned from those about the high-energy sky.
Exciting new types or faces of sources are revealed through penetrating
gamma-rays, such as sources embedded in interstellar clouds or pulsars
which accelerate particles in an immensely-strong magnetosphere.
The study of non-thermal particles in cosmic objects and of
radioactive decays from nucleosynthesis or positron annihilation
is a unique capability of INTEGRAL.
Lively discussions of current results and issues took place in Sardinia.
Among other topics, the attention was caught by the deepening surveys
with now over 400 and often variable sources, where observations at
other wavelengths often allow quite detailed astrophysical analyses.
The quasar at z=3.668 is the most distant source seen by INTEGRAL,
reported in the October POM. Many sources exhibit now very clear
power-law-type hard emission extensions beyond the thermal regime, which
are thought to be related to plasma jets developing from accretion onto
the compact conponent of binaries. From the sources with emission above
150 keV, about half are unidentified and promise new insights.
Polarization states of gamma-ray emission have been reported now, and
may add a new window onto the geometry of pulsars and particle
accelerators. More detailed and more complex pictures of 26Al
radioactivity and of positron annihilation emission in the Galaxy
promise to enlighten the morphology of the interstellar medium,
massive-star and binary-system activities on larger scales in the
Galaxy, and particle propagation near such active high-energy
sources. Phase resolved spectra of pulsars provide new and stringent
constraints, to help us disentangle the complex geometries of these
cosmic particle accelerators. The contributions of White Dwarfs and
X-ray binaries to the Galactic Ridge emission, and of obscured AGN to
the cosmic high-energy background, are more tightly constrained through
direct measurements at peak energies of those objects' emission than
through models inferred from lower-energy observations and theories.
The range and depth of the workshop discussions underlined the scientific
productivity of the INTEGRAL mission. Instruments & spacecraft are in
very good condition, so that several more years of fruitful observations
can be expected, as recently also recommended by ESA's advisory bodies.
