Results of investigation of radio galaxies of the survey "Cold": photometry, colour redshifts and the age of the stellar population

BVRI data for the majority of the objects of the RC catalogue with steep spectra and $m_R<{24}^m$ are presented. These data have been used to estimate colour redshifts and the age of stellar systems of host galaxies. By way of example of distant radio galaxies it is shown that this approach gives an accuracy of redshift estimates close to that for field galaxies ($\sim 20$ %). The age estimates are less confident, however, the lower age limit for not too distant ($z<1.5$) objects is determined quite reliably. Several galaxies have been detected that have an age above that of the Universe at the given $z$ in a simple CDM model of the Universe. A possibility of using such objects to specify the part played by ``dark energy’’ is discussed. This paradox disappears in a model with the $\mathrm{\Lambda }$-term equal to 0.6–0.8.