Star formation in radio galaxies at large redshift

Abstract

Optical continuum and emission-line observations of many high-redshift radio galaxies show a morphology which aligns the optical emission along the axis of the extended radio source. Shock-induced star formation has been suggested as a source of this emission, and calculations have been performed to test this hypothesis. Numerical simulations of high-energy radio jets passing through a dense protogalactic gas have been performed, with subsequent cooling and collapse of star formation. The resulting distribution of stars is elongated along the axis of the radio source but is also always highly limb-brightened in the direction normal to the radio axis. With a star formation efficiency of 10%, simulations for different jet velocities, densities, and star formation thresholds show that ~ 10^10^ M_sun_ in stars can be formed by this process over 10^8^ yr.