Multifrequency study of GHz-peaked spectrum sources
  Gigahertz-Peaked spectrum (GPS) sources are compact active galactic nuclei,
presumably young precursors of bright radio sources. The study of GPS radio
properties provides information about the features of synchrotron radiation in
extragalactic sources. Also in applied research GPS sources are useful as
compact stationary radio sources in the sky for astrometric purposes. This
paper presents the results of a multifrequency GPS study based on
quasi-simultaneous measurements with the RATAN-600 radio telescope during the
2006-2017. The catalog containing spectral flux densities measured at six
frequencies (1.1, 2.3, 4.8, 7.7/8.2, 11.2, and 21.7 GHz) have been obtained. In
addition, for the analysis of radio spectra, data from the following
low-frequency surveys have been used: GLEAM (GaLactic and Extragalactic All-sky
Murchison widefield array survey) and TGSS (Tata institute for fundamental
research GMRT Sky Survey) and high-frequency measurements from Planck survey. A
total number of 164 GPS and candidates to GPS have been identified (17 of them
are new discoveries), which makes up a small fraction of GPS in the initial
sample of bright AGNs, about 2%. The physical properties and formation
conditions of synchrotron radiation is found to be quite different in GPS of
different AGN types. The deficit of distant GPS ($z > 2$) with low maximum
frequencies (less than 1 GHz) is confirmed. The existing 'size - peak
frequency' anticorrelation is continuous. The continuum radio spectra are found
to become statistically steeper with increasing redshift.
