Using adaptive mesh-refinement cosmological hydrodynamic simulations with a physically motivated supernova feedback prescription we show that the standard cold dark matter model can account for extant observed properties of damped Lyman alpha systems ( DLAs ) .
We then examine the properties of DLA host galaxies .
We find : ( 1 ) While DLA hosts roughly trace the overall population of galaxies at all redshifts , they are always gas rich and have tendencies of being slightly smaller and bluer .
( 2 ) The history of DLA evolution is cosmological in nature and reflects primarily the evolution of the underlying cosmic density , galaxy size and galaxy interactions .
With higher density and more interactions at high redshift DLAs are larger in both absolute terms and in relative terms with respect to virial radii of halos .
( 3 ) The variety of DLAs at high redshift is richer with a large contribution coming from galactic filaments , created through close galaxy interactions .
The portion of gaseous disks of galaxies where most stars reside makes relatively small contribution to DLA incidence at z = 3 - 4 .
( 4 ) The vast majority of DLAs arise in halos of mass M _ { h } = 10 ^ { 10 } -10 ^ { 12 } { M _ { \odot } } at z = 1.6 - 4 , as these galaxies dominate the overall population of galaxies then .
At z = 3 - 4 , 20-30 % of DLA hosts are Lyman Break Galaxies ( LBGs ) , 10-20 % are due to galaxies more massive than LBGs and 50-70 % are from smaller galaxies .
( 5 ) Galactic winds play an indispensable role in shaping the kinematic properties of DLAs .
Specifically , the high velocity width DLAs are a mixture of those arising in high mass , high velocity dispersion halos and those arising in smaller mass systems where cold gas clouds are entrained to high velocities by galactic winds .
( 6 ) In agreement with observations , we see a weak but noticeable evolution in DLA metallicity .
The metallicity distribution centers at [ Z / H ] = -1.5 to -1 and spans more than three decades at z = 3 - 4 , with the peak moving to [ Z / H ] = -0.75 at z = 1.6 and [ Z / H ] = -0.5 by z = 0 .
( 7 ) The star formation rate of DLA hosts is concentrated in the range 0.3 - 30 { M _ { \odot } } /yr at z = 3 - 4 , gradually shifting lower to peak at \sim 0.5 - 1 { M _ { \odot } } /yr by z = 0 .