New Radio Data on Sources of the Big Trio Program for Searching for Distant Radio Galaxies

Abstract: A sample of objects with steep and ultra-steep spectra was prepared from radio sources of the Cold experiment surveys conducted on the RATAN-600 radio telescope. It formed the basis for the Big Trio program for searching for distant radio galaxies. With the advent of high-sensitivity, high-angular-resolution radio sky surveys, as well as deep optical and infrared surveys, it became possible to conduct additional studies of the sample. We refined the morphology and spectra of continuous radio emissions from radio galaxies. A detailed study of the morphological features of the sample sources revealed that 4 of the sample sources are formed by close radio sources with a distance of about 60 kpc between the parent galaxies. 8% of the radio sources demonstrate a restart of activity in the radio range, 20% of the sources are in an environment that leads to the deformation of the lobes, 11% are young sources and 2% are fading. A high percentage of sources with a variability index greater than 3 is associated with a large difference in the angular resolution of the compared TXS and VCSS surveys, as well as an underestimated flux density for some double sources in the latter survey. Comparison of spectral indices obtained from old and new data showed that in the studied sample the share of sources with steep spectra has significantly decreased. Most likely, this is due to the addition of low-frequency GLEAM data, although for some radio sources a possible evolution of the continuum spectrum over an interval of several decades is not excluded -- a shift towards low frequencies.