http://arxiv.org/abs/1802.00445
We introduce non-equilibrium molecular hydrogen chemistry into the radiation-hydrodynamics code Ramses-RT. This is an adaptive mesh refinement grid code with radiation hydrodynamics that couples the thermal chemistry of hydrogen and helium to moment-based radiative transfer with the Eddington tensor closure model. The H2 physics that we include are formation on dust grains, gas phase formation, collisional destruction, photodissociation, photoionisation, and self-shielding. In particular, we implement the first model for H2 self-shielding that is tied locally to moment-based radiative transfer by enhancing photo-destruction. This self-shielding from Lyman-Werner line overlap is critical to H2 formation and gas cooling. We can now track the non-equilibrium evolution of molecular, atomic, and ionised hydrogen species with their corresponding dissociating and ionising photon groups. Over a series of tests we show that our model works well compared to specialised photodissociation region codes. We successfully reproduce the transition depth between molecular and atomic hydrogen, molecular cooling of the gas, and a realistic Stroemgren sphere embedded in a molecular medium. In this paper we focus on test cases to demonstrate the validity of our model on small scales, but our ultimate application in the future will be large-scale galactic simulations.
S. Nickerson, R. Teyssier and J. Rosdahl
Mon, 5 Feb 18
41/52
Comments: 26 pages, 18 figures, submitted to MNRAS
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