We discuss the clustering properties of galaxies with signs of ongoing star formation detected by the Spitzer Space Telescope at 24 \mu m band in the SWIRE Lockman Hole field .
The sample of mid-IR-selected galaxies includes \sim 20000 objects detected above a flux threshold of S _ { 24 \mu m } = 310 \mu Jy .
We adopt optical/near-IR color selection criteria to split the sample into the lower-redshift and higher-redshift galaxy populations .
We measure the angular correlation function on scales of \theta = 0.01 - 3.5 deg , from which , using the Limber inversion along with the redshift distribution established for similarly selected source populations in the GOODS fields ( ) , we obtain comoving correlation lengths of r _ { 0 } = 4.98 \pm 0.28 h ^ { -1 } Mpc and r _ { 0 } = 8.04 \pm 0.69 h ^ { -1 } Mpc for the low- z ( z _ { mean } = 0.7 ) and high- z ( z _ { mean } = 1.7 ) subsamples , respectively .
Comparing these measurements with the correlation functions of dark matter halos identified in the Bolshoi cosmological simulation ( ) , we find that the high-redshift objects reside in progressively more massive halos reaching M _ { tot } \gtrsim 3 \times 10 ^ { 12 } h ^ { -1 } M _ { \odot } , compared to M _ { tot } \gtrsim 7 \times 10 ^ { 11 } h ^ { -1 } M _ { \odot } for the low-redshift population .
Approximate estimates of the IR luminosities based on the catalogs of 24 \mu m sources in the GOODS fields show that our high- z subsample represents a population of “ distant ULIRGs ” with L _ { IR } > 10 ^ { 12 } L _ { \odot } , while the low- z subsample mainly consists of “ LIRGs ” , L _ { IR } \sim 10 ^ { 11 } L _ { \odot } .
The comparison of number density of the 24 \mu m selected galaxies and of dark matter halos with derived minimum mass M _ { tot } shows that only 20 % of such halos may host star-forming galaxies .