Theoretical and observational arguments suggest that there is a large amount of hot ( \sim 10 ^ { 6 } K ) , diffuse gas residing in the Milky Way ’ s halo , while its total mass and spatial distribution are still unclear .
In this work , we present a general model for the gas density distribution in the Galactic halo , and investigate the gas evolution under radiative cooling with a series of 2D hydrodynamic simulations .
We find that the mass inflow rate in the developed cooling flow increases with gas metallicity and the total gas mass in the halo .
For a fixed halo gas mass , the spatial gas distribution affects the onset time of the cooling catastrophe , which starts earlier when the gas distribution is more centrally-peaked , but does not substantially affect the final mass inflow rate .
The gravity from the Galactic bulge and disk affects gas properties in inner regions , but has little effect on the final inflow rate either .
We confirm our results by investigating cooling flows in several density models adopted from the literature , including the Navarro-Frenk-White ( NFW ) model , the cored-NFW model , the Maller & Bullock model , and the \beta model .
Typical mass inflow rates in our simulations range from \sim 5 M _ { \odot } yr ^ { -1 } to \sim 60 M _ { \odot } yr ^ { -1 } , and are much higher than the observed star formation rate in our Galaxy , suggesting that stellar and active galactic nucleus feedback processes may play important roles in the evolution of the Milky Way ( MW ) and MW-type galaxies .