Combining the Swift/BAT and the INTEGRAL/ISGRI observations
  Current surveys of Active Galactic Nuclei (AGN) find only a very small
fraction of AGN contributing to the Cosmic X-ray Background (CXB) at energies
above 15 keV. Roughly 99% of the CXB is so far unresolved. In this work we
address the question of the unresolved component of the CXB with the combined
surveys of INTEGRAL and Swift. These two currently flying X-ray missions
perform independent surveys at energies above 15 keV. Our approach is to
perform the independent surveys and merge them in order to enhance the exposure
time and reduce the systematic uncertainties. We do this with resampling
techniques. As a result we obtain a new survey over a wide sky area of 6200
deg2 that is a factor ~4 more sensitive than the survey of Swift or INTEGRAL
alone. Our sample comprises more than 100 AGN. We use the extragalactic source
sample to resolve the CXB by more than a factor 2 compared to current parent
surveys.
