Broadband Studies of Decameter Carbon Radio Recombination Lines Toward Cygnus A and Perseus A Radio Galaxies

Radio recombination lines (RRLs) have proven themselves as a convenient tool for interstellar medium (ISM) diagnostics. Their observations at low frequencies, particularly at decameter waves, provide the precise and independent method for determining of physical parameters of cold, partially ionized cosmic plasma. In this paper results of highly sensitive decameter carbon RRLs observations carried out at Ukrainian UTR-2 radio telescope for ISM regions lying toward Cygnus A and Perseus A radio galaxies have been described. For the first time it was become possible to detect decameter carbon RRLs toward Cygnus A. The ISM studying by means of decameter RRLs in directions towards bright extragalactic sources is an important branch of modern astrophysics and the using of Ukrainian radio telescopes for these purposes is very promising.