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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. Stacking the low-resolution (R ∼ 800) spectra greatly increases the signal-to-noise ratio (S/N), 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, Lyα S/N restricted stack of 50,000 HETDEX LAEs shows the ensemble biweight averagez ∼ 2.6 LAE to be a blue (UV continuum slope ∼ −2.4 and E(B – V) < 0.1), moderately bright (Mysub>UV</sub> ∼ −19.7) star-forming galaxy with strong Lyα emission (log L<sub>Lyα</sub> ∼ 42.8 and W<sub>λ</sub>(Lyα) ∼ 114 Å), and potentially significant leakage of ionizing radiation. The rest-frame UV light is dominated by a young, metal-poor stellar population with an average age of 5–15 Myr and metallicity of 0.2–0.3 Z<sub>⊙</sub>.
