The Wyoming Survey for H-alpha. I. Initial Results at z ~ 0.16 and 0.24

TL;DR

The Wyoming Survey for H-alpha (WySH) is a large ground-based imaging project that measures H-alpha emission from galaxies at redshifts 0.16 and 0.24, revealing evolution in cosmic star formation rates over time.

Contribution

This paper presents initial results from WySH, including luminosity functions and star formation rate measurements at two redshifts, demonstrating the survey's capability to track cosmic star formation evolution.

Findings

Detected evolution in star formation rate density from z~0.16 to 0.24.

Measured star formation rates of 0.009 and 0.014 h_70 M_sun/yr/Mpc^3 at the two epochs.

Estimated uncertainties include >40% from fit errors and ~25% from cosmic variance.

Abstract

The Wyoming Survey for H-alpha, or WySH, is a large-area, ground-based, narrowband imaging survey for H-alpha-emitting galaxies over the latter half of the age of the Universe. The survey spans several square degrees in a set of fields of low Galactic cirrus emission. The observing program focuses on multiple dz~0.02 epochs from z~0.16 to z~0.81 down to a uniform (continuum+line) luminosity at each epoch of ~10^33 W uncorrected for extinction (3sigma for a 3" diameter aperture). First results are presented here for 98+208 galaxies observed over approximately 2 square degrees at redshifts z~0.16 and 0.24, including preliminary luminosity functions at these two epochs. These data clearly show an evolution with lookback time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the extinction-corrected H-alpha luminosity functions indicate star formation rates per co-moving volume of 0.009 and 0.014 h_70 M_sun/yr/Mpc^3 at z~0.16 and 0.24, respectively. The formal uncertainties in the Schechter fits, based on this initial subset of the survey, correspond to uncertainties in the cosmic star formation rate density at the >~40% level; the tentative uncertainty due to cosmic variance is 25%, estimated from separately carrying out the analysis on data from the first two fields with substantial datasets.