z ~ 1 Lyα EMITTERS. I. THE LUMINOSITY FUNCTION

Area of Science:

• Cosmic evolution
• Galaxy evolution
• Astrophysics

Background:

• Lyman-alpha emitters (LAEs) are crucial tracers of cosmic reionization and galaxy evolution.
• Existing LAE samples have gaps, particularly between redshift z~0.3 and z~1.
• The Galaxy Evolution Explorer (GALEX) provides valuable ultraviolet data for studying early galaxies.

Purpose of the Study:

• To construct a flux-limited sample of LAEs at z~1 to fill observational gaps.
• To investigate the active galactic nucleus (AGN) fraction and its relation to Lyα luminosity.
• To determine the luminosity function (LF) and volumetric Lyα escape fraction at z~1.

Main Methods:

• Utilized a novel data cube search method on GALEX grism data to identify candidate LAEs.
• Employed archival and new optical spectra for redshift verification.
• Combined UV, optical, and X-ray data to estimate AGN fraction and correct the LF.

Main Results:

• Compiled a sample of 135 candidate z~1 LAEs with luminosities comparable to high-redshift objects.
• Estimated the AGN fraction and its dependence on Lyα luminosity.
• Computed the LF from 60 confirmed z~1 LAEs, showing a luminosity density increase from z~0.3 to z~2.
• Determined a z~1 volumetric Lyα escape fraction of 0.7% ± 0.4%.

Conclusions:

• The constructed LAE sample bridges a significant gap in observational data.
• The luminosity density of the universe increased substantially from z~0.3 to z~2.
• The study provides crucial constraints on the Lyα escape fraction at z~1, impacting models of early galaxy feedback.