--- res: bibo_abstract: - Directly characterising the first generations of stars in distant galaxies is a key quest of observational cosmology. We present a case study of ID53 at z = 4.77, the UV-brightest (but L⋆) star-forming galaxy at z > 3 in the MUSE eXtremely Deep Field with a mass of ≈109 M⊙. In addition to very strong Lyman-α (Lyα) emission, we clearly detect the (stellar) continuum and an N V P Cygni feature, interstellar absorption, fine-structure emission and nebular C IV emission lines in the 140 h spectrum. Continuum emission from two spatially resolved components in Hubble Space Telescope data are blended in the MUSE data, but we show that the nebular C IV emission originates from a subcomponent of the galaxy. The UV spectrum can be fit with recent BPASS stellar population models combined with single-burst or continuous star formation histories (SFHs), a standard initial mass function, and an attenuation law. Models with a young age and low metallicity (log10(age/yr) = 6.5–7.6 and [Z/H] = −2.15 to −1.15) are preferred, but the details depend on the assumed SFH. The intrinsic Hα luminosity of the best-fit models is an order of magnitude higher than the Hα luminosity inferred from Spitzer/IRAC data, which either suggests a high escape fraction of ionising photons, a high relative attenuation of nebular to stellar dust, or a complex SFH. The metallicity appears lower than the metallicity in more massive galaxies at z = 3 − 5, consistent with the scenario according to which younger galaxies have lower metallicities. This chemical immaturity likely facilitates Lyα escape, explaining why the Lyα equivalent width is anti-correlated with stellar metallicity. Finally, we stress that uncertainties in SFHs impose a challenge for future inferences of the stellar metallicity of young galaxies. This highlights the need for joint (spatially resolved) analyses of stellar spectra and photo-ionisation models.@eng bibo_authorlist: - foaf_Person: foaf_givenName: Jorryt J foaf_name: Matthee, Jorryt J foaf_surname: Matthee foaf_workInfoHomepage: http://www.librecat.org/personId=7439a258-f3c0-11ec-9501-9df22fe06720 orcid: 0000-0003-2871-127X - foaf_Person: foaf_givenName: Anna foaf_name: Feltre, Anna foaf_surname: Feltre - foaf_Person: foaf_givenName: Michael foaf_name: Maseda, Michael foaf_surname: Maseda - foaf_Person: foaf_givenName: Themiya foaf_name: Nanayakkara, Themiya foaf_surname: Nanayakkara - foaf_Person: foaf_givenName: Leindert foaf_name: Boogaard, Leindert foaf_surname: Boogaard - foaf_Person: foaf_givenName: Roland foaf_name: Bacon, Roland foaf_surname: Bacon - foaf_Person: foaf_givenName: Anne foaf_name: Verhamme, Anne foaf_surname: Verhamme - foaf_Person: foaf_givenName: Floriane foaf_name: Leclercq, Floriane foaf_surname: Leclercq - foaf_Person: foaf_givenName: Haruka foaf_name: Kusakabe, Haruka foaf_surname: Kusakabe - foaf_Person: foaf_givenName: Tanya foaf_name: Urrutia, Tanya foaf_surname: Urrutia - foaf_Person: foaf_givenName: Lutz foaf_name: Wisotzki, Lutz foaf_surname: Wisotzki bibo_doi: 10.1051/0004-6361/202142187 bibo_volume: 660 dct_date: 2022^xs_gYear dct_isPartOf: - http://id.crossref.org/issn/0004-6361 - http://id.crossref.org/issn/1432-0746 dct_language: eng dct_publisher: EDP Sciences@ dct_subject: - Space and Planetary Science - Astronomy and Astrophysics - 'galaxies: high-redshift / techniques: spectroscopic / galaxies: stellar content / galaxies: formation' dct_title: 'Deciphering stellar metallicities in the early universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field@' ...