2020ApJ...896..136B -
Astrophys. J., 896, 136-136 (2020/June-3)
Modeling photoionized turbulent material in the circumgalactic medium. II. Effect of turbulence within a stratified medium.
BUIE II E., GRAY W.J., SCANNAPIECO E. and SAFARZADEH M.
Abstract (from CDS):
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☉ and turbulence that decreases radially. The simulations assume a metallicity of 0.3 Z☉ 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 x 1049 erg yr–1, produces a CGM that matches many of the observed ionic column densities and ratios. In this simulation, the NNV/NOVI 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.
Abstract Copyright:
© 2020. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Circumgalactic medium - Astrochemistry
Simbad objects:
3
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