Scrutiny of a very young, metal-poor star-forming Lyα emitter at <i>z</i> ≈ 3.7

ABSTRACT The origin of the Lyman α (Lyα) emission in galaxies is a long-standing issue: despite several processes known to originate this line (e.g. active galactic nucleus, star formation, cold accretion, shock heating), it difficult discriminate among these phenomena based on observations. Recent studies have suggested that comparison ultraviolet (UV) and optical properties sources could solve riddle. For reason, we investigate rest-frame UV Abell 2895b, strongly lensed Lyα emitter at redshift z ∼ 3.7. From study, find our target compact (rn 1.2 pkpc) star-forming (star formation rate ≃11 M⊙ yr−1) galaxy having young stellar population. Interestingly, measure high ratio Hβ continuum monochromatic luminosities (L(Hβ)/L(UV) ≃ 100). Based tracks theoretical models (starburst99 bpass), can only partially explain result by assuming recent (≲10 Myr), bursty episode considering characterized binary stars, top-heavy initial mass function subsolar metallicities (Z ≲ 0.01 Z⊙). These assumptions also observed low (C/O) abundance (≃0.23(C/O)⊙). By comparing data sets, are more extended (×2) than Balmer lines, peak offset (≃0.6 pkpc). multiwavelength results analysis suggest originates from burst, likely taking place an off-centre clump.