Speaker
Dr
Eugenio Bottacini
(Stanford University)
Description
In the view of the so-called Active Galactic Nuclei (AGN) unified model
the nuclear activity is powered by a super-massive black hole (SMBH)
at the center of the AGN. An optically thick gas-dust structure surrounding
the SMBH absorbs efficiently the nuclear radiation.
Current surveys of the INTEGRAL Soft-Gamma Ray Imager (IBIS/ISGRI) and of the
Burst Alert Telescope (BAT) on board the Swift satellite have proven to be
a powerful technique to detect AGNs at soft gamma-ray energies.
BAT and IBIS/ISGRI are coded-mask detectors having two major advantages:
1) they have a huge field of view, hence allowing to detect an large number of
AGNs 2) they operate at soft gamma-rays, hence collecting photons that are
energetic enough to pierce efficiently through the gas-dust structure surrounding
the SMBH. However the sensitivity of coded-mask detectors is limited by heavy
systematic uncertainties. Furthermore by design they block ~50% of the incident
photons causing an increase of statistical noise. This prevents the detection
of the most absorbed AGNs.
In this talk I will show that the BAT and the IBIS/ISGRI observations can be
merged in order to produce a deep sky survey less susceptible to systematic
and statistical noise. The survey of this virtual new mission extends over a wide
sky area of 6200 deg^2 sampling 113 sources. The scientific outcome from the study
of the sample has been properly addressed to study the evolution of AGNs in the local
Universe. Our results are compared to other missions and predictions on future scheduled
missions are made. I discuss also the expected results when applying this survey to the
entire extragalactic sky and preliminary results of this survey on the Galactic center are shown.
Primary author
Dr
Eugenio Bottacini
(Stanford University)
