Global Star Formation Rate Density over 0.7<z<1.9

TL;DR

This study measures the star formation rate density between redshifts 0.7 and 1.9 using HST grism spectroscopy, finding results consistent with previous work and confirming the peak of cosmic star formation at z>1.5.

Contribution

First to use HST-NICMOS grism spectroscopy for a large sample of emission-line galaxies to determine star formation rate density in this redshift range.

Findings

Star formation rate density at z=1.4 is 0.138 Msun/yr/Mpc^3.

Luminosity function fits a Schechter function with specified parameters.

Results support the peak of star formation at z>1.5.

Abstract

We determine the global star formation rate 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 pure parallel mode throughout HST Cycles 12 and 13, our survey covers ~104 arcmin2 from which we select 80 galaxies with likely redshifted Ha emission lines. In several cases, a somewhat weaker [OIII] doublet emission is also detected. The Ha luminosity range of the emission-line galaxy sample is 4.4 x 10^41 < L(Ha) < 1.5 x 10^43 erg/s. In this range, the luminosity function is well described by a Schechter function with phi* = (4.24\pm3.55) x 10^-3 Mpc^-3, L* = (2.88\pm1.58) x 10^42 erg/s, and alpha = -1.39\pm0.43. We derive a volume-averaged star formation rate density of 0.138\pm0.058 Msun/yr/Mpc3 at z=1.4 without an extinction correction. Subdividing the redshift range, we find star formation rate densities of 0.088\pm0.056 Msun/yr/Mpc3 at z=1.1 and 0.265\pm0.174 Msun/yr/Mpc3 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.