A relationship between the X-ray luminosity and redshift of extragalactic objects

An analysis performed on a sample of 191 extragalactic X-ray sources of different classes (QSOs, Seyfert Galaxies, BL Lac, elliptical and SO, spiral and irregular galaxies) appears to show a general relationship between log z and the logarithm of the 2keV equivalent monochromatic luminosity of the brightest object in a given redshift interval (regardless of the class of the object). This function is almost constant for z#lt#0.001; it has a continuous inflection of about two orders of magnitude between z=0.001 and z=0.01, and at z#gt#0.01, where only AGNs are present, it matches with a straight line, with slope equal to 1.6. It is suggested that such a smooth function implies a physical continuity of these objects. (author)