GLOBAL STAR FORMATION RATE DENSITY OVER 0.7 < z < 1.9

We determine the global star formation rate (SFR) density at 0.7 < z < 1.9 using emission-line-selected galaxies identified in Hubble Space Telescope-Near Infrared Camera and Multi-Object Spectrograph (HST-NICMOS) grism spectroscopy observations. Observing in a pure parallel mode throughout HST Cycles 12 and 13, our survey covers similar to 104 arcmin(2) from which we select 80 galaxies with likely redshifted H alpha emission lines. In several cases, a somewhat weaker [O III] doublet emission is also detected. The Ha luminosity range of the emission-line galaxy sample is 4.4 x 10(41) < L(H alpha) < 1.5 x 10(43) erg s(-1). In this range, the luminosity function is well described by a Schechter function with phi* = ( 4.24 +/- 3.55) x 10(-3) Mpc(-3), L* = (2.88 +/- 1.58) x 10(42) erg s(-1), and alpha = -1.39 +/- 0.43. We derive a volume-averaged SFR density of 0.138 +/- 0.058 M(circle dot) yr(-1) Mpc(-3) at z = 1.4 without an extinction correction. Subdividing the redshift range, we find SFR densities of 0.088 +/- 0.056 M(circle dot) yr(-1) Mpc(-3) at z = 1.1 and 0.265 +/- 0.174 M(circle dot) yr(-1) Mpc(-3) at z = 1.6. The overall star formation rate density is consistent with previous studies using Ha when the same average extinction correction is applied, confirming that the cosmic peak of star formation occurs at z > 1.5.