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arXiv · 2006.03066

Modeling Photoionized Turbulent Material in the Circumgalactic Medium II: Effect of Turbulence within a Stratified Medium

Edward Buie II·William J. Gray·Evan Scannapieco·Mohammadtaher Safarzadeh
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Abstract

The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of OVI absorption accompanied by little to no detectable NV absorption. This unusual spectral signature, accompanied by highly non-uniform absorption from lower ionization state species, indicates that the CGM must be viewed as a dynamic, multiphase medium, such as occurs in the presence of turbulence. Motivated by previous isotropic turbulent simulations, we carry out chemodynamical simulations of stratified media in a Navarro-Frenk-White (NFW) gravitational potential with a total mass of $10^{12}$ solar masses and turbulence that decreases radially. The simulations assume a metallicity of 0.3 solar, a redshift zero metagalatic UV background, and they track ionizations, recombinations, and species-by-species radiative cooling using the MAIHEM package. We compare a suite of ionic column densities with the COS-Halos sample of low-redshift star-forming galaxies. Turbulence with an average one-dimensional velocity dispersion approximately 40 km/s, corresponding to an energy injection rate of approximately $10^{49}$ erg/yr, produces a CGM that matches many of the observed ionic column densities and ratios. In this simulation, the NVI to OVI ratio is suppressed from its equilibrium value due to a combination of radiative cooling and cooling from turbulent mixing. This level of turbulence is consistent with expectations from observations of better constrained, higher-mass systems, and could be sustained by energy input from supernovae, gas inflows, and dynamical friction from dark matter subhalos. We also conduct a higher resolution run which yields smaller-scale structures, but remains in agreement with observations.

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Edward Buie II, William J. Gray, Evan Scannapieco, Mohammadtaher Safarzadeh. 2020-06-04. Modeling Photoionized Turbulent Material in the Circumgalactic Medium II: Effect of Turbulence within a Stratified Medium. https://doi.org/10.3847/1538-4357%2Fab9535

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