TY - JOUR
T1 - A simple model for molecular hydrogen chemistry coupled to radiation hydrodynamics
AU - Nickerson, Sarah
AU - Teyssier, Romain
AU - Rosdahl, Joakim
N1 - Funding Information:
We thank the anonymous reviewer for their many insightful comments and suggestions. SN is supported by the University of Zürich Candoc Scholarship, and performed these simulations on the Piz Daint supercomputer in the Swiss National Supercomputing Centre (CSCS) in Lugano. JR was funded by the European Research Council under the European Union’s Seventh Frame-work Programme (FP7/2007-2013) / ERC Grant agreement 278594-GasAroundGalaxies and the ORAGE project from the Agence Na-tionale de la Recherche under grant ANR-14-CE33-0016-03.
Publisher Copyright:
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
PY - 2018/9/21
Y1 - 2018/9/21
N2 - 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, formation by three-body collisions, collisional destruction, photodissociation, photoionization, cosmic ray ionization, 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 photodestruction. 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 ionized hydrogen species with their corresponding dissociating and ionizing photon groups. Over a series of tests we show that our model works well compared to specialized photodissociation region codes.We successfully reproduce the transition depth between molecular and atomic hydrogen, molecular cooling of the gas, and a realistic Strömgren sphere embedded in a molecular medium. In this paper we focus on test cases to demonstrate the validity of our model on small scales. Our ultimate goal is to implement this in large-scale galactic simulations.
AB - 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, formation by three-body collisions, collisional destruction, photodissociation, photoionization, cosmic ray ionization, 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 photodestruction. 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 ionized hydrogen species with their corresponding dissociating and ionizing photon groups. Over a series of tests we show that our model works well compared to specialized photodissociation region codes.We successfully reproduce the transition depth between molecular and atomic hydrogen, molecular cooling of the gas, and a realistic Strömgren sphere embedded in a molecular medium. In this paper we focus on test cases to demonstrate the validity of our model on small scales. Our ultimate goal is to implement this in large-scale galactic simulations.
KW - Methods: numerical
KW - Molecular processes
KW - Radiative transfer
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U2 - 10.1093/mnras/sty1556
DO - 10.1093/mnras/sty1556
M3 - Article
AN - SCOPUS:85051566240
SN - 0035-8711
VL - 479
SP - 3206
EP - 3226
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 3
ER -