We present “ radially-resolved-equilibrium-models ” for the growth of stellar and gaseous disks in cosmologically accreting massive halos .
Our focus is on objects that evolve to redshifts z \sim 2 .
We solve the time-dependent equations that govern the radially dependent star-formation rates , inflows and outflows from and to the inter- and circum-galactic medium , and inward radial gas flows within the disks .
The stellar and gaseous disks reach equilibrium configurations on dynamical time scales much shorter than variations in the cosmological dark matter halo growth and baryonic accretions rates .
We show analytically that mass and global angular momentum conservation naturally give rise to exponential gas and stellar disks over many radial length scales .
As expected , the gaseous disks are more extended as set by the condition Toomre Q < 1 for star-formation .
The disks rapidly become baryon dominated .
For massive , 5 \times 10 ^ { 12 } M _ { \odot } halos at redshift z = 2 , we reproduced the typical observed star-formation rates of \sim 100 M _ { \odot } { yr } ^ { -1 } , stellar masses \sim 9 \times 10 ^ { 10 } M _ { \odot } , gas contents \sim 10 ^ { 11 } M _ { \odot } , half mass sizes of 4.5 and 5.8 kpc for the stars and gas , and characteristic surface densities of 500 and 400 M _ { \odot } { pc } ^ { -2 } for the stars and gas .