Atomic chemistry in turbulent astrophysical media. II. Effect of the redshift zero metagalactic background
- Lawrence Livermore National Laboratory, P.O. Box 808, L-038, Livermore, CA 94550 (United States)
- School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1494 (United States)
We carry out direct numerical simulations of turbulent astrophysical media exposed to the redshift zero metagalactic background. The simulations assume solar composition and explicitly track ionizations, recombinations, and ion-by-ion radiative cooling for hydrogen, helium, carbon, nitrogen, oxygen, neon, sodium, magnesium, silicon, sulfur, calcium, and iron. Each run reaches a global steady state that depends not only on the ionization parameter, U, and mass-weighted average temperature, T{sub MW}, but also on the one-dimensional turbulent velocity dispersion, σ{sub 1D}. We carry out runs that span a grid of models with U ranging from 0 to 10{sup −1} and σ{sub 1D} ranging from 3.5 to 58 km s{sup −1}, and we vary the product of the mean density and the driving scale of the turbulence, nL, which determines the average temperature of the medium, from nL=10{sup 16} to nL=10{sup 20} cm{sup −2}. The turbulent Mach numbers of our simulations vary from M≈0.5 for the lowest velocity dispersion cases to M≈20 for the largest velocity dispersion cases. When M≲1, turbulent effects are minimal, and the species abundances are reasonably described as those of a uniform photoionized medium at a fixed temperature. On the other hand, when M≳1, dynamical simulations such as the ones carried out here are required to accurately predict the species abundances. We gather our results into a set of tables to allow future redshift zero studies of the intergalactic medium to account for turbulent effects.
- OSTI ID:
- 22886995
- Journal Information:
- Astrophysical Journal, Vol. 818, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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