Star Formation in High Redshift Radio Galaxies

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 (~10⁴⁵ erg /s) radio jets passing through a dense protogalactic gas have been performed, with subsequent cooling and collapse to 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 ten percent, simulations for different jet velocities, densities and star formation threshold show that ~10¹⁰ M_o in stars be formed by this process over 10⁸ years.