The VANDELS survey: a strong correlation between Ly α equivalent width and stellar metallicity at 3 ≤ z ≤ 5

Cullen, F.F.CullenMcLure, R. J.R. J.McLureDunlop, J. S.J. S.DunlopCarnall, A. C.A. C.CarnallMcLeod, D. J.D. J.McLeodShapley, A. E.A. E.ShapleyAmorín, R.R.AmorínBOLZONELLA, MICOLMICOLBOLZONELLACASTELLANO, MARCOMARCOCASTELLANOCimatti, A.A.CimattiCirasuolo, M.M.CirasuoloCUCCIATI, OlgaOlgaCUCCIATIFONTANA, AdrianoAdrianoFONTANAFONTANOT, FabioFabioFONTANOTGARILLI, BIANCA MARIA ROSABIANCA MARIA ROSAGARILLIGuaita, L.L.GuaitaJarvis, M. J.M. J.JarvisPENTERICCI, LauraLauraPENTERICCIPOZZETTI, LuciaLuciaPOZZETTITalia, M.M.TaliaZamorani, G.G.ZamoraniCalabrò, A.A.CalabròCRESCI, GIOVANNIGIOVANNICRESCIFynbo, J. P. U.J. P. U.FynboHathi, N. P.N. P.HathiGiavalisco, M.M.GiavaliscoKoekemoer, A.A.KoekemoerMANNUCCI, FILIPPOFILIPPOMANNUCCISAXENA, AAYUSHAAYUSHSAXENA2022-03-242022-03-2420200035-8711http://hdl.handle.net/20.500.12386/31889We present the results of a new study investigating the relationship between observed Ly α equivalent width (Wλ(Ly α)) and the metallicity of the ionizing stellar population ( Z⋆) for a sample of 768 star-forming galaxies at 3 ≤ z ≤ 5 drawn from the VANDELS survey. Dividing our sample into quartiles of rest-frame Wλ(Ly α) across the range $-58 \,\rm {\mathring{\rm A}} \lesssim$ Wλ(Ly α) $\lesssim 110 \,\rm {\mathring{\rm A}}$ , we determine Z⋆ from full spectral fitting of composite far-ultraviolet spectra and find a clear anticorrelation between Wλ(Ly α) and Z⋆. Our results indicate that Z⋆ decreases by a factor ≳ 3 between the lowest Wλ(Ly α) quartile (<Wλ(Ly α) $\rangle =-18\,\rm {\mathring{\rm A}}$ ) and the highest Wλ(Ly α) quartile (<Wλ(Ly α) $\rangle =24\,\rm {\mathring{\rm A}}$ ). Similarly, galaxies typically defined as Lyman alpha emitters (LAEs; Wλ(Ly α) $\gt 20\,\rm {\mathring{\rm A}}$ ) are, on average, metal poor with respect to the non-LAE galaxy population (Wλ(Ly α) $\le 20\,\rm {\mathring{\rm A}}$ ) with Z⋆non-LAE ≳ 2 × Z⋆LAE. Finally, based on the best-fitting stellar models, we estimate that the increasing strength of the stellar ionizing spectrum towards lower Z⋆ is responsible for ${\simeq}15{-}25{{\ \rm per\ cent}}$ of the observed variation in Wλ(Ly α) across our sample, with the remaining contribution ( ${\simeq}75{-}85{{\ \rm per\ cent}}$ ) being due to a decrease in the H I/dust covering fractions in low- Z⋆ galaxies.STAMPAenThe VANDELS survey: a strong correlation between Ly α equivalent width and stellar metallicity at 3 ≤ z ≤ 5Article10.1093/mnras/staa12602-s2.0-85091979874https://academic.oup.com/mnras/article/495/1/1501/5835232?login=truehttp://arxiv.org/abs/2001.11063v22020MNRAS.495.1501CFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation