**Table 1:** Photometric redshifts for Optically Faint Sources in CDF-S/GOODS.
XID^a	R mag	$z_{\rm spec}$	$z_{\rm phot}$	1 $\sigma$ ^b	template^c	odds^d	X/O^e	$N_{\rm H}$ ^f	$L_{\rm X}$ ^g	Class X^h
	(Vega)								([0.5-10] keV)
45	25.4	2.291	2.37	2.23-2.43	1.67	0.97	23.8	$\rm 22.91^{23.05}_{22.74}$	44.18	QSO abs
58	26.0	...	0.92	0.75-1.07	2.00	0.60	19.2	$\rm 22.40^{22.49}_{22.31}$	43.16	AGN abs
79	26.5	...	2.00	1.91-2.07	1.00	0.98	36.4	<21.75	43.67	AGN unabs
79A $^{\ast}$	26.5	...	1.82	1.76-1.86	1.33	1.00	36.4	<21.75	43.67	AGN unabs
81	26.0	...	2.59	2.47-2.59	2.33	0.95	10.2	$\rm 22.63^{22.86}_{22.26}$	43.81	AGN abs
82	25.9	...	1.89	1.79-1.97	1.33	0.97	12.1	$\rm 23.47^{23.52}_{23.42}$	43.79	AGN abs
108	25.9	...	1.56	1.48-1.66	2.33	0.96	8.4	$\rm 21.79^{22.28}_{19.90}$	43.15	AGN unabs
117	25.5	2.573	2.75	2.50-3.00	1.33	0.85	8.5	$\rm 22.49^{22.70}_{22.16}$	43.99	AGN abs
124	25.3	...	0.61	0.45-0.77	3.00	0.53	0.3	<21.62	41.75	galaxy
133	99.0	...	1.21	0.78-4.08	2.00	0.11	21.9	$\rm 22.75^{22.85}_{22.66}$	43.32	AGN abs
146	99.0	...	2.67	2.55-2.66	1.67	0.97	42.3	>24.18	45.11	QSO abs
147	25.1	...	0.99	0.89-1.10	2.00	0.87	16.3	$\rm 23.39^{23.45}_{23.33}$	43.67	AGN abs
148	27.3	...	1.74	1.62-1.88	1.67	0.87	69.9	>24.18	45.09	QSO abs
159	99.0	...	3.30	3.17-3.46	3.67	0.98	142.8	$\rm 23.00^{23.11}_{22.88}$	44.81	QSO abs
178	26.0	...	0.29	0.23-3.54	3.67	0.32	0.7	$\rm 21.68^{22.02}_{20.52}$	41.00	galaxy
210	99.0	...	1.73	1.60-1.95	1.33	0.74	18.1	$\rm 22.32^{22.56}_{21.87}$	43.36	AGN abs
217	25.8	...	7.72	1.08-7.62	5.00	0.30	0.8	$\rm 23.06^{23.31}_{22.61}$	43.80	AGN abs
221	99.0	...	2.51	2.34-2.62	1.00	0.90	1.6	$\rm 22.58^{23.00}_{21.08}$	43.32	AGN abs
226	99.0	...	1.45	1.14-1.87	5.67	0.39	24.4	$\rm 22.17^{22.35}_{21.88}$	43.35	AGN abs
227	99.0	...	2.18	1.98-2.36	1.33	0.77	33.8	$\rm 23.83^{23.91}_{23.74}$	44.24	QSO abs
240	25.0	...	1.41	1.35-1.53	1.33	0.95	4.4	$\rm 22.42^{22.62}_{22.22}$	43.13	AGN abs
243	99.0	...	7.89	7.56-7.93	4.00	0.99	40.2	$\rm 23.26^{23.36}_{23.16}$	44.11	QSO abs
263	25.3	3.660	3.50	3.32-3.56	3.33	0.97	5.5	>24.18	44.54	QSO abs
265	99.0	1.215	1.16	1.09-1.24	1.33	0.98	51.2	$\rm 23.20^{23.27}_{23.13}$	43.70	AGN abs
508	99.0	...	2.50	1.90-2.85	1.00	0.58	18.8	$\rm 23.88^{23.97}_{23.79}$	44.15	QSO abs

^a XID from Giacconi et al. (2002).
^b 1 $\sigma$ confidence range.
^c Best fit template. BPZ performs two interpolations between each one of the following templates:
1: Elliptical (CWW);
2: Sbc (CWW);
3: Scd (CWW);
4: Irregular (CWW);
5: SB3 (Kinney);
6: SB2 (Kinney).
^d Odds parameter which gives a metric on the reliability of the photometric redshift determination (see Sect. 4.2).
^e X-ray-to-optical flux ratios.
^f Logaritm of the column density.
^g Logaritm of the unabsorbed X-ray luminosity in the [0.5-10] keV band. The uncertainties are smaller than 0.01 in the adopted units.
^h X-ray classification (see Sect. 4.1).
$^{\ast}$ Photometric redshift obtained using the UDF photometry (see Sect. 9 and Figs. 13, 14).

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