We report deep Giant Metrewave Radio Telescope ( GMRT ) 610 MHz continuum imaging of four sub-fields of the DEEP2 Galaxy Redshift Survey .
We stacked the radio emission in the GMRT images from a near-complete ( absolute blue magnitude { M _ { B } } \leq - 21 ) sample of 3698 blue star-forming galaxies with redshifts 0.7 \lesssim z \lesssim 1.45 to detect ( at \approx 17 \sigma significance ) the median rest-frame 1.4 GHz radio continuum emission of the sample galaxies .
The stacked emission is unresolved , with a rest-frame 1.4 GHz luminosity of L _ { 1.4 GHz } = ( 4.13 \pm 0.24 ) \times 10 ^ { 22 } W Hz ^ { -1 } .
We used the local relation between total star formation rate ( SFR ) and 1.4 GHz luminosity to infer a median total SFR of ( 24.4 \pm 1.4 ) M _ { \odot } yr ^ { -1 } for blue star-forming galaxies with M _ { B } \leq - 21 at 0.7 \lesssim z \lesssim 1.45 .
We detect the main-sequence relation between SFR and stellar mass , M _ { \star } , obtaining SFR = ( 13.4 \pm 1.8 ) \times [ ( M _ { \star } / ( 10 ^ { 10 } M _ { \odot } ) ] ^ { 0.73 \pm 0.09 } M% _ { \odot } yr ^ { -1 } ; the power-law index shows no change over z \approx 0.7 - 1.45 .
We find that the nebular line emission suffers less extinction than the stellar continuum , contrary to the situation in the local Universe ; the ratio of nebular extinction to stellar extinction increases with decreasing redshift .
We obtain an upper limit of 0.87 Gyr to the atomic gas depletion time of a sub-sample of DEEP2 galaxies at z \approx 1.3 ; neutral atomic gas thus appears to be a transient phase in high- z star-forming galaxies .