NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-04-20 T19:50:18 PDT
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For refcode 2008A&A...485..707P:
Retrieve 34 NED objects in this reference.
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2008A&A...485..707P A deep INTEGRAL hard X-ray survey of the 3C 273/Coma region Paltani, S.; Walter, R.; McHardy, I. M.; Dwelly, T.; Steiner, C.; Courvoisier, T. J.-L. Abstract. We present an analysis of the deepest hard X-ray survey to date of about 2500 deg^2^ performed by the IBIS instrument on board INTEGRAL in the 20-60 keV band, with a total exposure time of 4 Ms. We find 34 candidate sources, for which we try to find counterparts at other wavelengths. The ratio of Seyfert 1 to Seyfert 2 is significantly more than the ratio found in the optical. This effect may be explained in the framework of the receding-torus model, but could also be due to absorption columns large enough to affect the 20-60 keV band. None of the predicted Compton-thick objects with 10^24^ < N_H_ < 10^25^ cm^-2^ is detected unambiguously; when taking lower limits on N_H_ into account, the fraction of these objects is found to be lower than 24%. We do not see, but cannot exclude, a relationship between absorption and luminosity similar to what is seen in the 2-10 keV band. Our data suggests the possibility of a lack of objects with 10^21^ <= N_H_ <= 10^22^ cm^-2^, which could be expected if absorption has two origins, for instance a torus-like structure and the host galaxy. We find that the Log N-Log S diagram of our sources is compatible with those obtained in other surveys in hard X-rays. Compared to models of the AGN population selected in the 2-10 keV band, the Log N-Log S diagram is generally in good agreement, but the N_H_ distribution is significantly different, with significantly less unabsorbed sources (N_H_ < 10^22^ cm^-2^) at a given flux limit compared to the models. In this survey, we resolve about 2.5% of the cosmic X-ray background in the 20-60 keV band. We also study the local hard X-ray luminosity function, which is compatible with what is found in other recent hard X-ray surveys. The characteristic luminosity Log L^*^_20-60~keV_=43.66 is found to be a factor about 5 lower than the value observed in the 2-10 keV band. We find a space density of 10^-3^ AGN with L_20-60~keV_>10^41^ per Mpc^3^ and a corresponding luminosity density of 0.9 x 10^39^ erg s^-1^ Mpc^-3^. Key words: surveys, galaxies: active, galaxies: seyfert, X-rays: diffuse background, X-rays: galaxies
Retrieve 34 NED objects in this reference.
Please click here for ADS abstract

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