TY - JOUR
T1 - Modeling Photoionized Turbulent Material in the Circumgalactic Medium. II. Effect of Turbulence within a Stratified Medium
AU - Buie, Edward
AU - Gray, William J.
AU - Scannapieco, Evan
AU - Safarzadeh, Mohammadtaher
N1 - Publisher Copyright:
© 2020. The American Astronomical Society. All rights reserved.
PY - 2020/6/20
Y1 - 2020/6/20
N2 - The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of O vi absorption accompanied by little to no detectable N v absorption. This unusual spectral signature, accompanied by highly nonuniform 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 1012 M o˙ and turbulence that decreases radially. The simulations assume a metallicity of 0.3 Z o˙ and 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 of ≈40 km s-1, corresponding to an energy injection rate of ≈4 1049 erg yr-1, produces a CGM that matches many of the observed ionic column densities and ratios. In this simulation, the N N V /N O VI 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 ≈40 km s-1 run, which yields smaller-scale structures but remains in agreement with observations.
AB - The circumgalactic medium (CGM) of nearby star-forming galaxies shows clear indications of O vi absorption accompanied by little to no detectable N v absorption. This unusual spectral signature, accompanied by highly nonuniform 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 1012 M o˙ and turbulence that decreases radially. The simulations assume a metallicity of 0.3 Z o˙ and 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 of ≈40 km s-1, corresponding to an energy injection rate of ≈4 1049 erg yr-1, produces a CGM that matches many of the observed ionic column densities and ratios. In this simulation, the N N V /N O VI 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 ≈40 km s-1 run, which yields smaller-scale structures but remains in agreement with observations.
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U2 - 10.3847/1538-4357/ab9535
DO - 10.3847/1538-4357/ab9535
M3 - Article
AN - SCOPUS:85087362631
SN - 0004-637X
VL - 896
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 136
ER -