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