HETDEX Public Source Catalog 1 -- Stacking 50K Lyman Alpha Emitters

Abstract

We describe the ensemble properties of the $1.9<z<3.5$ Lyman Alpha Emitters (LAEs) found in the HETDEX survey's first public data release, HETDEX Public Source Catalog 1 (Mentuch Cooper et al. 2023). Stacking the low-resolution ($R\sim$ 800) spectra greatly increases the signal-to-noise ratio, revealing spectral features otherwise hidden by noise, and we show that the stacked spectrum is representative of an average member of the set. The flux limited, Ly$\hat{I}\pm$ signal-to-noise ratio restricted stack of 50K HETDEX LAEs shows the ensemble biweight ``average" $z\sim 2.6$ LAE to be a blue (UV continuum slope $\sim -2.4$ and E(B-V) $<0.1$), moderately bright (M${}_{\text{UV}}\sim -19.7$) star forming galaxy with strong Ly$\hat{I}\pm$ emission (log $L_{Ly\hat{I}\pm }$ $\sim$ 42.8 and $W_{\hat{I}}»$(Ly$\hat{I}\pm$) $\sim$ 114Ã ), and potentially significant leakage of ionizing radiation. The restframe UV light is dominated by a young, metal poor stellar population with an average age 5-15 Myr and metallicity of 0.2-0.3 Z${}_{\odot }$.

17 pages, 11 figures, 2 data files (ApJ Accepted)