Lyα-emitting galaxies at z = 3.1: L* progenitors experiencing rapid star formation

We studied the clustering properties and multiwavelength spectral energy distributions of a complete sample of 162 Lyα-emitting (LAE) galaxies at z ≃ 3.1 discovered in deep narrowband MUSYC imaging of the Extended Chandra Deep Field-South. LAEs were selected to have observed frame equivalent widths >80 Å and emission line fluxes >1.5 × 10^-17 ergs cm^-2 s^-1. Only 1% of our LAE sample appears to host AGNs. The LAEs exhibit a moderate spatial correlation length of r₀ = 3.6_-1.0^+0.8 Mpc, corresponding to a bias factor b = 1.7_-0.4^+0.3, which implies median dark matter halo masses of log₁₀M_med = 10.9_-0.9^+0.5 M _⊙. Comparing the number density of LAEs, 1.5 ± 0.3 × 10^-3 Mpc^-3, with the number density of these halos finds a mean halo occupation ∼1%-10%. The evolution of galaxy bias with redshift implies that most z = 3.1 LAEs evolve into present-day galaxies with L < 2.5L*, whereas other z > 3 galaxy populations typically evolve into more massive galaxies. Halo merger trees show that z = 0 descendants occupy halos with a wide range of masses, with a median descendant mass close to that of L*. Only 30% of LAEs have sufficient stellar mass (>∼ 3 × 10⁹ M_⊙) to yield detections in deep Spitzer IRAC imaging. A two-population SED fit to the stacked UBVRIzJK+[3.6, 4.5, 5.6, 8.0] μm fluxes of the IRAC-undetected objects finds that the typical LAE has low stellar mass (1.0_-0.4^+0.6 × 10⁹ M _⊙), moderate star formation rate (2 ± 1 M _⊙ yr^-1),ayoung component age of 20_-10 ⁺³⁰ Myr, and little dust (A_V < 0.2). The bestfit model has 20% of the mass in the young stellar component, but models without evolved stars are also allowed.