Outputs

The quantities provided as outputs of hyperz have been already described in the previous section. Here we report an example of the .z_phot file:

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UBVRI.z_phot
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1	0.600	0.442	77.86	2	29	1.0152	1.20	0.368E+03	0.541	0.647	...	-18.90	1.380	0.00
2	3.020	0.032	96.89	1	28	0.7187	1.20	0.159E+05	2.791	3.051	...	-26.11	5.200	93.50
3	0.200	0.687	60.05	1	30	1.4340	1.00	0.162E+03	0.000	0.277	...	-14.03	1.940	0.02
4	3.200	0.071	99.09	5	27	0.5088	1.00	0.251E-06	2.899	3.332	...	-22.94	2.600	37.71
5	4.400	0.019	99.64	1	7	0.0100	1.20	0.110E+02	3.967	4.669	...	-22.61	2.800	87.07

As stated above, the format of this file is the following, ordered by columns: (1) the identification number; (2) the photometric redshift primary solution; (3) its $\chi^2_\nu$ and (4) the corresponding probability; (5) the number of the spectral type in the order of the spectra.param file; (6) the age record; (7) the age in Gyr; (8) the absorption in the $V$ band to be applied at the best fit SED; (9) the normalization factor $b$ of equation 1 needed to minimize the $\chi^2$; (10)-(11), (12)-(13) and (14)-(15) the limits of the confidence intervals at 99%, 90% and 68%; (16) the weighted mean redshift $z_{\rm wm}$; (17) the probability associated to $z_{\rm wm}$ (the columns 12 - 17 here are replaced by dots); (18) the absolute magnitude; (19) the secondary peak of the probability function; (20) the probability of the secondary solution.

One of the most considerable features of hyperz, is the possibility of knowing the probability function $P(z)$. This characteristic allows us to describe in an accurate way the results of different tests and to explore the relevance of secondary solutions and then the degeneracy in the parameter space. Moreover, the function$P(z)$ can be used to compute some cosmological quantities properly taking into account the characteristics of the photometric redshift technique. Figure 7 shows an example of SED fitting and the corresponding$P(z)$ for three objects.

Figure:Left: The best fit SED (solid line), with superimposed the observed points with error bars (vertical error bars correspond to photometric errors, horizontal error bars represent the surface covered by the filter) and the fluxes derived from the best fit SED (circles). Right: The probability functions relative to$\chi^2$ for the three considered objects.

2000-12-10