Jet propagation velocity and environment density of giant radio sources with steep radio spectrum
Before we have determined that giant radio structure is typical for steep-spectrum sources detected with Ukrainian T-shaped Radio Telescope of model 2 (UTR-2). To estimate the jet propagation velocity and environment density of giant radio sources we consider the sample of galaxies and quasars with steep radio spectrum compiled from two regions of UTR-2 catalogue. The value of velocity of jet propagation is obtained from our estimates of linear size of radio structure and characteristic age of a source. We use the obtained values of jet propagation velocity for the estimates of density of jet environment, that is, density of environment at galaxies and quasars outskirts. We have derived that values of jet propagation velocities of examined sources are ~10e9 cm/s. The positive correlation of jet velocity and redshift of sources is displayed in our sample. On the assumption of equality of jet luminosity and corresponding kinetic luminosity we estimate the density of jet environment (radio structure environment) for galaxies (10e-26 gcm-3 to 10e-27 gcm-3) and quasars (10e-28 gcm-3). Considered steep-spectrum galaxies and quasars display strong evolution of jet propagation velocity and jet environment density. Properties of giant steep-spectrum sources are in accordance with conception of long evolution of powerful sources. The steep low-frequency spectra may be as markers of giant radio structures of galaxies and quasars.