Detection of Lyman Continuum from 3.0 < z < 3.5 Galaxies in the HETDEX Survey

Abstract

Questions as to what drove the bulk reionization of the Universe, how that reionization proceeded, and how the hard ionizing radiation reached the intergalactic medium remain open and debated. Observations probing that epoch are severely hampered by the increasing amounts of neutral gas with increasing redshift, so a small, but growing number of experiments are targeting star forming galaxies ($z\sim 3$) as proxies. However, these studies, while providing fantastic detail, are time intensive, contain relatively few targets, and can suffer from selection biases. As a complementary alternative, we investigate whether stacking the already vast (and growing) numbers of low-resolution ($\Delta \lambda /\lambda =800$) Lyman-$\alpha$ Emitting (LAE) galaxy spectra from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) can be used to measure ionizing photons (restframe 880-910Å) escaping their galaxy hosts. As a blind survey, HETDEX avoids the biases from continuum selected galaxies and its planned 540 square degree coverage promotes the statistical power of large numbers. In this paper, we confirm the feasibility of Lyman continuum detection by carefully selecting a sample of \lyccount\ high redshift ($z\sim$3) LAEs from a subset of HETDEX observations, stacking their spectra and measuring a $\gtrsim$3$\sigma$ detection of $0.10\mu$Jy restframe Lyman continuum emission, uncorrected for attenuation in the intergalactic medium, over the full sample stack ($3.0<z<3.5$ and $-22.0\lesssim M_{\text{UV}}\lesssim -19.0$).

20 pages, 9 figures, 2 tables

References in corpus (4)

• The mean free path of ionizing photons at 5 < z < 6: evidence for rapid evolution near reionization
• An uncontaminated measurement of the escaping Lyman continuum at $z\sim 3$
• Correcting correlation functions for redshift-dependent interloper contamination
• Interrelation of the environment of Ly$\alpha$ emitters and massive galaxies at $2<z<4.5$

Cited by in corpus (1)

• The Synchrony of Production & Escape: Half the Bright Ly$\alpha$ Emitters at $z\approx 2$ have Lyman Continuum Escape Fractions $\approx 50\%$