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AR 14311 (Archival Research)

Mon Jul 15 04:40:31 GMT 2024

Principal Investigator: Claudia Scarlata
PI Institution: University of Minnesota - Twin Cities
Investigators (xml)

Title: Emission Line Galaxy Constraints from HST: Towards Accurate Forecasts for WFIRST and Euclid
Cycle: 23

Abstract
Dark energy is one of the most important unsolved problems in cosmology today. The planned, mutually complementary WFIRST and Euclid mission galaxy redshift surveys will use Halpha- and [OIII]-selected emission line galaxies as tracers of the large scale structure at 1 < z < 2 (Halpha) and 1.7 < z < 2.7 ([OIII]). To optimize these redshift surveys for the study of dark energy, it is critical to have a reliable and sufficiently precise knowledge of the expected numbers of Halpha galaxies in the survey volume. Additionally, WFIRST and Euclid's sample of emission-line galaxies will, like all slitless spectroscopy surveys, be affected by a complex selection function that depends on galaxy size and luminosity, line equivalent width, and redshift errors arising from the mis-identification of single emission-line galaxies. To maximize the science return of these redshift surveys, we need to be able to account for these effects in the forecast predictions. Here we propose to combine three slitless spectroscopic WFC3-IR datasets -- The CANDELS supernova follow-up, 3D-HST+AGHAST, and the WISP survey -- to: (1) obtain the most accurate estimate of the Halpha and [OIII] luminosity functions in the redshift ranges 0.7 - 1.6 and 1.2 - 2.2, respectively, (2) constrain the continuum luminosity, galaxy size, and EW distribution functions for line-emitters, and (3) quantify the expected number of contaminating redshifts from misidentified single emission lines. Our proposed analysis is of great relevance to ensure success of the planned WFIRST and Euclid missions.