Population III Host Candidates at z about2: Strong He II lambda1640 and Absent UV Metal Lines in HETDEX Ly alpha Emitters

Population III (Pop III) stars are expected to produce extremely hard ionizing spectra, yet direct evidence for their signature--strong narrow He II lambda1640 emission with weak or absent metal lines--remains elusive. Although Pop III formation peaks at z 10, models predict that nearly pristine gas pockets can survive to later times, making intermediate-redshift searches a probe of metal mixing across cosmic time. We search 109,545 high-confidence Ly α-emitting galaxies at 1.9<z<2.3 in the Hobby--Eberly Telescope Dark Energy Experiment's database for systems with strong He II lambda1640 and no detected UV metal lines, recovering eight candidates and a first-order, tentative comoving number density of about30 Gpc-3. The eight-object stack yields a rest-frame He II equivalent width of 28.7 plus or minus6.7 Angstrom, He II/Ly α=0.354 plus or minus0.094, and a resolution-corrected He II FWHM of 449 plus or minus105 km s-1. We find no significant N V, C IV, or O III] emission; using the He II width to set the scale, we derive 3σ upper limits of N V/He II <0.167, C IV/He II <0.128, and O III]/He II <0.140. This combination of strong He II, elevated He II/Ly α, moderate line width, and weak metal lines is difficult to reproduce with metal-enriched stellar populations, AGN narrow-line regions, shocks, or classical Wolf--Rayet features. We interpret the sample as candidates for very metal-poor or Pop III-like ionizing sources at z about2. Definitive confirmation requires deeper rest-UV spectroscopy to measure He II and metal-line limits in individual objects, followed by rest-optical spectroscopy of H β, [O III] lambda4959, lambda5007, [O II] lambda3727, and H α to constrain gas-phase metallicity, ionization conditions, and AGN activity.