Year: 2018
Type: article
Abstract: We report on the serendipitous discovery of a z = 4.0, M1500 = −22.20 star-forming galaxy (Ion3) showing copious Lyman continuum (LyC) leakage (∼60 per cent escaping), a remarkable multiple peaked Ly α emission, and significant Ly α radiation directly emerging at the resonance frequency. This is the highest redshift confirmed LyC emitter in which the ionizing and Ly α radiation possibly share a common ionized channel (with NH I < 1017.2 cm−2). Ion3 is spatially resolved, it shows clear stellar winds signatures like the P-Cygni N vλ1240 profile, and has blue ultraviolet continuum (β = −2.5 ± 0.25, Fλ ∼ λβ) with weak low-ionization interstellar metal lines. Deep VLT/HAWKI Ks and Spitzer/IRAC 3.6 and 4.5μm imaging show a clear photometric signature of the H α line with equivalent width of 1000 Å rest-frame emerging over a flat continuum (Ks − 4.5μm ≃ 0). From the SED fitting, we derive a stellar mass of 1.5 × 109 M⊙, SFR of 140 M⊙ yr−1 and age of ∼10 Myr, with a low dust extinction, E(B − V) ≲ 0.1, placing the source in the starburst region of the SFR−M* plane. Ion3 shows similar properties of another LyC emitter previously discovered (z = 3.21, Ion2, Vanzella et al. 2016). Ion3 (and Ion2) represents ideal high-redshift reference cases to guide the search for reionizing sources at z > 6.5 with JWST.
Institutions: Osservatorio astronomico di Bologna, National Institute for Astrophysics, Trieste Astronomical Observatory, Astronomical Observatory of Rome, European Southern Observatory, Astronomical Observatory of Capodimonte, University of Groningen, University of Ferrara, University of Copenhagen, University of Milan, Ludwig-Maximilians-Universität München, University of Massachusetts Amherst
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2779089293