Exploring the Milky Way Circumgalactic Medium in a Cosmological Context
  with a Semi-Analytic Model
  We combine the Santa-Cruz Semi-Analytic Model (SAM) for galaxy formation and
evolution with the circumgalactic medium (CGM) model presented in Faerman et
al. (2020) to explore the CGM properties of $L^{*}$ galaxies. We use the SAM to
generate a sample of galaxies with halo masses similar to the Milky Way (MW)
halo, $M_{\rm vir} \approx 10^{12}~{\rm M_{sun}}$, and find that the CGM mass
and mean metallicity in the sample are correlated. We use the CGM masses and
metallicities of the SAM galaxies as inputs for the FSM20 model, and vary the
amount of non-thermal support. The density profiles in our models can be
approximated by power-law functions with slopes in the range of $0.75 < a_n <
1.25$, with higher non-thermal pressure resulting in flatter distributions. We
explore how the gas pressure, dispersion measure, OVI-OVIII column densities,
and cooling rates behave with the gas distribution and total mass. We show that
for CGM masses below $\sim 3 \times 10^{10}~{\rm M_{sun}}$, photoionization has
a significant effect on the column densities of OVI and OVIII. The combination
of different MW CGM observations favors models with similar fractions in
thermal pressure, magnetic fields/cosmic rays, and turbulent support, and with
$M_{\rm gas} \sim 3-10 \times 10^{10}~{\rm M_{sun}}$. The MW OVI column
requires $t_{\rm cool}/t_{\rm dyn} \sim 4$, independent of the gas
distribution. The AGN jet-driven heating rates in the SAM are enough to offset
the CGM cooling, although exact balance is not required in star-forming
galaxies. We provide predictions for the columns densities of additional metal
ions - NV, NeVIII, and MgX.
