The Radiative Transport of Dust in Primordial Galaxies and Second‐Generation Star Formation

We investigate the radiative transport of dust in primordial galaxies in thepresence of the UV radiation field from the first metal-free stars. We findthat dust created in the first supernova (SN) explosions can be driven throughthe interior of the SN remnant to accumulate in the SN shells, wheresecond-generation stars may form from compressed cooling gas. This scenariorequires metal-free stars to form continuously over timescales of up to 10 Myr,consistent with recent estimates. Silicate and graphite grains, as well asiron-bearing magnetites, are transported to the shells for reasonable parameterassumptions, but their relative yields from primordial SNe is an importantfactor in the resulting abundance ratios. We compare the results of segregatedgrain transport with the current nucleosynthetic data on extremely metal-poorGalactic halo stars. Fossil signatures of this process may already have beendetected in those iron-poor stars with enhanced carbon and silicate elementssuch as magnesium, silicon and oxygen. We discuss the implications of ourresults for the transition from first- to second-generation star formation inprimordial galaxies, and the role played by the radiative transport of dust inthis process.Comment: Accepted by ApJ; 10 ApJ-style pages, 5 figures. Minor revisions with added text, results and figures unchanged. Will appear in ApJ v. 640, 20 March 2006 issu