INTEGRAL/IBIS all-sky survey in hard X-rays

We present results of an all-sky hard X-ray survey based on almost four years of observations with the IBIS telescope onboard the INTEGRAL observatory. The dead time-corrected exposure of the survey is similar to 33 Ms. Approximately 12% and 80% of the sky has been covered to limiting fluxes lower than 1 and 5 mCrab, respectively. Our catalog of detected sources includes 403 objects, 316 of which exceed a 5 sigma detection threshold on the time-averaged map of the sky, and the rest were detected in various subsamples of exposures. Among the identified sources, 219 are Galactic (90 low-mass X-ray binaries, 76 high-mass X-ray binaries, 21 cataclysmic variables, 6 coronally active stars, and other types) and 137 are extragalactic, including 130 active galactic nuclei (AGNs) and 3 galaxy clusters. We derived number-flux functions of AGNs and Galactic sources. The log N-log S relation of non-blazar AGNs is based on 68 sources located at Galactic latitudes |b| > 5 degrees, where the survey is characterized by high identification completeness, with fluxes higher than S-lim = 1.1 x 10(-11) erg s(-1) cm(-2) (similar to 0.8 mCrab) in the 17-60 keV energy band. The cumulative AGN number-flux function can be described by a power law with a slope of 1.62 +/- 0.15 and normalization of (5.7 +/- 0.7) x 10(-3) sources per deg(2) at fluxes >1.43 x 10(-11) erg s(-1) cm(-2) (>1 mCrab). Those AGNs with fluxes higher than S-lim make up similar to 1% of the cosmic X-ray background at 17-60 keV. We present evidence of strong inhomogeneity in the spatial distribution of nearby (less than or similar to 70 Mpc) AGNs, which reflects the large-scale structure in the local Universe.