All Figures

$\begin{figure} \par\fbox{\includegraphics[width=8.6cm,clip]{9450_fig1}}\end{figure}$ Figure 1: Exposure map of the mosaic around 3C 273. The contours are located at 0, 10, 100, 300 and 500 ks respectively. Coordinates are right ascension and declination. Dots indicate the location of detected sources.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{9450_fig2}\end{figure}$ Figure 2: Histogram of the pixels' significance for the part of the mosaic exposed for more than 10 ks. The red/gray curve is a Gaussian fit to the part of the histogram with $\sigma \le 3$ .
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In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{9450_fig3}\end{figure}$ Figure 3: Top: significance distribution of the pseudo-sources extracted randomly from the mosaic (black line). The red/gray line is a Gaussian fit to the part with $\sigma <4$ . The excesses in the significance distribution at $\sigma >4$ indicate true sources. Bottom: probability that the significance $\sigma$ of a fake source extracted at a specific position is by chance larger than a given significance $\sigma _0$ (black line). The red/gray line gives the probability to find a fake source with significance $\sigma >\sigma _0$ anywhere in the mosaic.
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In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{9450_fig4}\end{figure}$ Figure 4: Surface of the sky over which a given flux results in a significance $\sigma \ge 5.5$ (solid line) and $\sigma \ge 5.0$ (dashed line). The vertical dotted line shows the sensitivity limit of other hard X-ray surveys.
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In the text

$\begin{figure} \par\includegraphics[width=6.7cm,clip]{9450_fig5}\end{figure}$ Figure 5: Combined Chandra and ISGRI spectrum of MCG-03-34-064 in the 0.3-60 keV energy range. The source is well fitted by a model (solid line) consisting of a very absorbed power-law (dashed line) plus a reflection component (dot-dot-dashed line) and an Fe line (dotted line). A very steep component, probably due to scattered X-ray emission, is visible below 2 keV (dot-dot-dot-dashed line).
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In the text

$\begin{figure} \par\includegraphics[width=8.1cm,clip]{9450_fig6}\end{figure}$ Figure 6: Relationship between $N_{{\rm H}}$ measured in X-ray observations and that derived from the counterpart in RASS-BSC. Coma and M 87 are dominated by thermal emission in the soft X-ray band, and are therefore excluded.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{9450_fig7}\end{figure}$ Figure 7: Histogram of the $N_{{\rm H}}$ distribution for the sources from Table 3. Sources are weighted by their probabilities. The blue/dark gray histogram shows sources with measured intrinsic $N_{{\rm H}}$ 's. The green/light gray histogram shows the sources whose $N_{{\rm H}}$ is derived from the presence of a counterpart in the RASS-BSC. The red/medium gray histogram shows the sources without counterparts in the RASS-BSC, with log $N_{{\rm H}}$ evenly distributed between 22.25 and 25.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{9450_fig8}\end{figure}$ Figure 8: $N_{{\rm H}}$ vs. luminosity for all sources with significance $\sigma >5$ , the Coma cluster and blazars having been excluded. Blue/dark gray filled squares correspond to objects with actual $N_{{\rm H}}$ measurements. Green/light gray open squares correspond to objects whose $N_{{\rm H}}$ 's have been determined using their fluxes in RASS-BSC. Red/medium gray arrows are lower limits based on the absence of X-ray counterparts. The heavy black line shows the fraction of absorbed AGN ( $N_{{\rm H}}$ $\ge$ 10²² cm^-2) in two luminosity bins, L<10⁴³ and L>10⁴³ erg s^-1. The gray area shows the 1 $\sigma$ uncertainties on these fractions.
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In the text

$\begin{figure} \par\includegraphics[width=14.6cm,clip]{9450_fig9}\end{figure}$ Figure 9: $\log N$ - $\log S$ diagrams for the sources detected by INTEGRAL. In all panels the solid lines are from our work and the dashed or dotted line are model extrapolations from U03. Top left: $\log N$ - $\log S$ for the full list of candidate sources with the 1 $\sigma$ uncertainties. The solid line is the power-law best fit. Top right: $\log N$ - $\log S$ in two redshift bins; red/medium gray: z < 0.05; blue/dark gray: z>0.05. Bottom left: $\log N$ - $\log S$ in two luminosity bins; red/medium gray: $L_{20-60~{\rm keV}} < 10^{43.5}$ ; blue/dark gray: $L_{20-60~{\rm keV}} > 10^{43.5}$ . Bottom right: $\log N$ - $\log S$ in two $N_{{\rm H}}$ bins; red/medium gray: $N_{{\rm H}}$ < 10²² cm^-2; blue/dark gray: $N_{{\rm H}}$ > 10²² cm^-2.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{9450_fig10a}\hspace*{1.3cm} \includegraphics[width=7.8cm,clip]{9450_fig10b}\end{figure}$ Figure 10: Left: AGN luminosity function in the 20-60 keV range. The points have been calculated using the $V/V_{{\rm max}}$ estimator. The heavy solid line is the $\Phi (L)$ distribution from Eq. (1) with L^*, $\alpha$ and $\beta$ parameters determined using a maximum-likelihood method and $\Phi ^*$ obtained by fitting the $V/V_{{\rm max}}$ points. Short-dashed line is the LF from Beckmann et al. (2006); dotted line is that from Sazonov et al. (2007); long-dashed line is that from Tueller et al. (2008). Right: uncertainty contours in the L^*- $\alpha$ plane. The solid and dotted lines mark the 1, 2, 3 and 0.5, 1.5, 2.5 $\sigma$ thresholds respectively.
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In the text

$\begin{figure} \par\fbox{\includegraphics[width=8.6cm,clip]{9450_fig1}}\end{figure}$	Figure 1: Exposure map of the mosaic around 3C 273. The contours are located at 0, 10, 100, 300 and 500 ks respectively. Coordinates are right ascension and declination. Dots indicate the location of detected sources.
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$\begin{figure} \par\includegraphics[width=8.2cm,clip]{9450_fig2}\end{figure}$	Figure 2: Histogram of the pixels' significance for the part of the mosaic exposed for more than 10 ks. The red/gray curve is a Gaussian fit to the part of the histogram with $\sigma \le 3$ .
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$\begin{figure} \par\includegraphics[width=7.9cm,clip]{9450_fig4}\end{figure}$	Figure 4: Surface of the sky over which a given flux results in a significance $\sigma \ge 5.5$ (solid line) and $\sigma \ge 5.0$ (dashed line). The vertical dotted line shows the sensitivity limit of other hard X-ray surveys.
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$\begin{figure} \par\includegraphics[width=6.7cm,clip]{9450_fig5}\end{figure}$	Figure 5: Combined Chandra and ISGRI spectrum of MCG-03-34-064 in the 0.3-60 keV energy range. The source is well fitted by a model (solid line) consisting of a very absorbed power-law (dashed line) plus a reflection component (dot-dot-dashed line) and an Fe line (dotted line). A very steep component, probably due to scattered X-ray emission, is visible below 2 keV (dot-dot-dot-dashed line).
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$\begin{figure} \par\includegraphics[width=8.1cm,clip]{9450_fig6}\end{figure}$	Figure 6: Relationship between $N_{{\rm H}}$ measured in X-ray observations and that derived from the counterpart in RASS-BSC. Coma and M 87 are dominated by thermal emission in the soft X-ray band, and are therefore excluded.
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