---
res:
  bibo_abstract:
  - We present an analysis of the UV continuum slope, β, using a sample of 726 galaxies
    with z > 4, selected from a mixture of JWST ERS, GTO, and GO observational programs.
    We considered only spectroscopic data obtained with the low-resolution (R ∼ 30 − 300)
    PRISM/CLEAR NIRSpec configuration. Studying the correlation between β and MUV,
    we find an overall decreasing trend, described by β = ( − 0.055 ± 0.017)MUV + ( − 2.98 ± 0.34).
    This is consistent with previous studies, where brighter galaxies show redder
    β values. However, when analyzing the trend in separate redshift bins, we find
    that at high redshift the relation becomes much flatter and is consistent with
    a flat slope within 1σ. Furthermore, we find that β tends to decrease with redshift,
    following β = ( − 0.075 ± 0.010)z + ( − 1.496 ± 0.056). This is consistent with
    most recent results showing a steepening of the spectra at higher z. We selected
    a sample of galaxies with extremely blue slopes (i.e., β < −2.6). Such slopes
    are steeper than predicted by stellar evolution models – even for dust-free, young,
    metal-poor populations – when the contribution of nebular emission is included.
    We selected 44 extremely blue galaxies (XBGs) and investigated the possible physical
    origin of their steep slopes by comparing them to a subsample of redder galaxies
    (matched in Δz = ±0.5 and ΔMUV = ±0.2). We find that XBGs have younger stellar
    populations, stronger ionization fields, lower dust attenuation, and lower but
    not pristine metallicity (∼10% Z⊙) compared to red galaxies. However, these properties
    alone cannot explain the extreme β values. Using indirect inference of Lyman continuum
    escape with the most recent models, we estimated the escape fraction fesc > 10%
    in at least 25% of the XBGs, whereas all the red sources exhibit much lower fesc
    values. A reduced nebular continuum contribution – resulting from either a high
    escape fraction or a bursty star formation history – is likely the origin of the
    extremely blue slopes.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: D.
      foaf_name: Dottorini, D.
      foaf_surname: Dottorini
  - foaf_Person:
      foaf_givenName: A.
      foaf_name: Calabrò, A.
      foaf_surname: Calabrò
  - foaf_Person:
      foaf_givenName: L.
      foaf_name: Pentericci, L.
      foaf_surname: Pentericci
  - foaf_Person:
      foaf_givenName: Sara
      foaf_name: Mascia, Sara
      foaf_surname: Mascia
      foaf_workInfoHomepage: http://www.librecat.org/personId=edaf889c-c7cd-11ef-ab1b-bb28c431bd29
  - foaf_Person:
      foaf_givenName: M.
      foaf_name: Llerena, M.
      foaf_surname: Llerena
  - foaf_Person:
      foaf_givenName: L.
      foaf_name: Napolitano, L.
      foaf_surname: Napolitano
  - foaf_Person:
      foaf_givenName: P.
      foaf_name: Santini, P.
      foaf_surname: Santini
  - foaf_Person:
      foaf_givenName: G.
      foaf_name: Roberts-Borsani, G.
      foaf_surname: Roberts-Borsani
  - foaf_Person:
      foaf_givenName: M.
      foaf_name: Castellano, M.
      foaf_surname: Castellano
  - foaf_Person:
      foaf_givenName: R.
      foaf_name: Amorin, R.
      foaf_surname: Amorin
  - foaf_Person:
      foaf_givenName: M.
      foaf_name: Dickinson, M.
      foaf_surname: Dickinson
  - foaf_Person:
      foaf_givenName: A.
      foaf_name: Fontana, A.
      foaf_surname: Fontana
  - foaf_Person:
      foaf_givenName: N.
      foaf_name: Hathi, N.
      foaf_surname: Hathi
  - foaf_Person:
      foaf_givenName: M.
      foaf_name: Hirschmann, M.
      foaf_surname: Hirschmann
  - foaf_Person:
      foaf_givenName: A. M.
      foaf_name: Koekemoer, A. M.
      foaf_surname: Koekemoer
  - foaf_Person:
      foaf_givenName: R. A.
      foaf_name: Lucas, R. A.
      foaf_surname: Lucas
  - foaf_Person:
      foaf_givenName: E.
      foaf_name: Merlin, E.
      foaf_surname: Merlin
  - foaf_Person:
      foaf_givenName: A.
      foaf_name: Morales, A.
      foaf_surname: Morales
  - foaf_Person:
      foaf_givenName: F.
      foaf_name: Pacucci, F.
      foaf_surname: Pacucci
  - foaf_Person:
      foaf_givenName: S.
      foaf_name: Wilkins, S.
      foaf_surname: Wilkins
  - foaf_Person:
      foaf_givenName: P.
      foaf_name: Arrabal Haro, P.
      foaf_surname: Arrabal Haro
  - foaf_Person:
      foaf_givenName: M.
      foaf_name: Bagley, M.
      foaf_surname: Bagley
  - foaf_Person:
      foaf_givenName: S. L.
      foaf_name: Finkelstein, S. L.
      foaf_surname: Finkelstein
  - foaf_Person:
      foaf_givenName: J.
      foaf_name: Kartaltepe, J.
      foaf_surname: Kartaltepe
  - foaf_Person:
      foaf_givenName: C.
      foaf_name: Papovich, C.
      foaf_surname: Papovich
  - foaf_Person:
      foaf_givenName: N.
      foaf_name: Pirzkal, N.
      foaf_surname: Pirzkal
  bibo_doi: 10.1051/0004-6361/202453267
  bibo_volume: 698
  dct_date: 2025^xs_gYear
  dct_identifier:
  - UT:001510826300019
  dct_isPartOf:
  - http://id.crossref.org/issn/0004-6361
  - http://id.crossref.org/issn/1432-0746
  dct_language: eng
  dct_publisher: EDP Sciences@
  dct_title: 'Evolution of the UV slope of galaxies at cosmic morning (z > 4): The
    properties of extremely blue galaxies@'
...