**Table 4:** X-ray spectral parameters of OFS with a spectroscopic redshift in the CDF-S.
XID^a	CXO CDFS^b	counts^c	$\Gamma ^d$	$N_{\rm H}^{e}$	$L_{\rm X}^{f}$	cstat^g
45	J033225.8-274306	$302\pm18$	$\rm 1.46^{1.68}_{1.26}$	$\rm 22.91^{23.05}_{22.74}$	$1.51 \times 10^{44}$	150.7
54	J033214.7-275422	$186\pm17$	$\rm 1.38^{1.72}_{1.10}$	$\rm 23.03^{23.21}_{22.79}$	$1.18 \times 10^{44}$	153.8
117	J033203.1-274450	$136\pm15$	1.8	$\rm 22.49^{22.70}_{22.16}$	$9.72 \times 10^{43}$	126.4
263	J033218.9-275136	$46\pm9$	$\rm 1.75^{2.10}_{1.40}$	>24.18	$3.48 \times 10^{44}$	60.1
265	J033233.4-274236	$114\pm14$	1.8	$\rm 23.20^{23.27}_{23.13}$	$5.00 \times 10^{43}$	107.9
606	J033225.0-275009	$33\pm8$	1.8	$\rm 23.27^{23.40}_{23.14}$	$1.45 \times 10^{43}$	59.9

^a XID from Giacconi et al. (2002).
^b IAU registered name, based on original X-ray coordinates.
^c Net counts in the [0.5-10] keV band.
^d Spectral Index and 90% confidence range (Tozzi et al. 2005).
^e Logaritm of the intrinsic absorption (and 90% confidence range) (Tozzi et al. 2005).
^f X-ray luminosity in [0.5-10] keV band, deabsorbed and in erg s^-1 (Tozzi et al. 2005).
^g C-statistic coefficient from the model fitting.

Source LaTeX | All tables | In the text

	1 Introduction
	2 The sample
	3 Comparison of the optically bright and optically faint X-ray source samples
	4 Photometric redshift technique applied to an X-ray selected sample
	5 The properties of OFS with spectroscopic redshifts
	6 X-ray-to-optical flux ratios
	7 X-ray spectroscopy
	8 X-ray absorbed QSOs
	9 Ultra deep field
	10 Conclusions
	References