Numerical Simulation of Star Formation by the Bow Shock of the Centaurus A Jet

Abstract

Recent Hubble Space Telescope ( HST ) observations of the extragalactic radio source Centaurus A (Cen A) display a young stellar population around the southwest tip of the inner filament 8.5 kpc from the galactic center of Cen A, with ages in the range 1–3 Myr. Crockett et al. have argued that the transverse bow shock of the Cen A jet triggered this star formation as it impacted dense molecular cores of clouds in the filament. To test this hypothesis, we perform three-dimensional numerical simulations of star formation induced by the jet bow shock in the inner filament of Cen A, using a positivity-preserving, weighted, essentially non-oscillatory method to solve the equations of gas dynamics with radiative cooling. We find that star clusters form inside a bow-shocked molecular cloud when the maximum initial density of the cloud is ≥ 40 H 2 molecules cm −3 . In a typical molecular cloud of mass 10 6 M ⊙ and diameter 200 pc, approximately 20 star clusters of mass 10 4 M ⊙ are formed, matching the HST images.