VANZELLA, ErosErosVANZELLANONINO, MarioMarioNONINOCUPANI, GuidoGuidoCUPANICASTELLANO, MARCOMARCOCASTELLANOSani, E.E.SaniMIGNOLI, MarcoMarcoMIGNOLICALURA, FrancescoFrancescoCALURAMENEGHETTI, MASSIMOMASSIMOMENEGHETTIGILLI, RobertoRobertoGILLICOMASTRI, AndreaAndreaCOMASTRIMERCURIO, AMATAAMATAMERCURIOCaminha, G. B.G. B.CaminhaCaputi, K.K.CaputiRosati, P.P.RosatiGrillo, C.C.GrilloCRISTIANI, StefanoStefanoCRISTIANIBalestra, I.I.BalestraFONTANA, AdrianoAdrianoFONTANAGiavalisco, M.M.Giavalisco2021-04-162021-04-1620181745-3925http://hdl.handle.net/20.500.12386/30775We report on the serendipitous discovery of a z = 4.0, M<SUB>1500</SUB> = -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 N<SUB>H I</SUB> < 10<SUP>17.2</SUP> cm<SUP>-2</SUP>). 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, F<SUB>λ</SUB> ˜ λ<SUP>β</SUP>) 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 × 10<SUP>9</SUP> M<SUB>⊙</SUB>, SFR of 140 M<SUB>⊙</SUB> yr<SUP>-1</SUP> 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.STAMPAenArticle10.1093/mnrasl/sly0232-s2.0-85044376068https://academic.oup.com/mnrasl/article/476/1/L15/48506472018MNRAS.476L..15VFIS/05 - ASTRONOMIA E ASTROFISICA