EDP Sciences
Free access
Issue
A&A
Volume 475, Number 2, November IV 2007
Page(s) 775 - 784
Section Online catalogs and data
DOI http://dx.doi.org/10.1051/0004-6361:20077191


A&A 475, 775-784 (2007)
DOI: 10.1051/0004-6361:20077191

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

R. Krivonos1, 2, M. Revnivtsev1, 2, A. Lutovinov2, 1, S. Sazonov1, 2, E. Churazov1, 2, and R. Sunyaev1, 2

1  Max-Planck-Institute für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching bei München, Germany
    e-mail: krivonos@mpa-garching.mpg.de
2  Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia

(Received 29 January 2007 / Accepted 27 July 2007)

Abstract
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 ~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°, where the survey is characterized by high identification completeness, with fluxes higher than $S_{\rm lim}$ = 1.1 $\times$ 10-11 erg s-1 cm-2(~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 $\pm$ 0.15 and normalization of (5.7$\pm$0.7) $\times$ 10-3 sources per deg2 at fluxes > 1.43 $\times$ 10-11 erg s-1 cm-2(>1 mCrab). Those AGNs with fluxes higher than $S_{\rm lim}$ make up ~1% of the cosmic X-ray background at 17-60 keV. We present evidence of strong inhomogeneity in the spatial distribution of nearby ($\la$70 Mpc) AGNs, which reflects the large-scale structure in the local Universe.


Key words: surveys -- X-rays: general -- Galaxy: general -- galaxies: Seyfert -- cosmology: large-scale structure of Universe



© ESO 2007