Photodissociation of H2 in Protogalaxies: Modeling Self-Shielding in 3D Simulations

Understand

The ability of primordial gas to cool in proto-galactic haloes exposed to Lyman-Werner (LW) radiation is critically dependent on the self-shielding of H_2.

• We perform radiative transfer calculations of LW line photons, post-processing outputs from three-dimensional adaptive mesh refinement (AMR) simulations of haloes with T_vir > 10^4 K at redshifts around z=10.
• We calculate the optically thick photodissociation rate numerically, including the effects of density, temperature, and velocity gradients in the gas, as well as line overlap and shielding of H_2 by HI, over a large number of sight-lines.
• In low-density regions (n<10^4 cm^-3) the dissociation rates exceed those obtained using most previous approximations by more than an order of magnitude; the correction is smaller at higher densities.