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The Spectral Evolution of the First Galaxies. III. Simulated James Webb Space Telescope Spectra of Reionization-epoch Galaxies with Lyman-continuum Leakage

Research output: Contribution to journalArticle

  • Erik Zackrisson
  • Christian Binggeli
  • Kristian Finlator
  • Nickolay Y. Gnedin
  • Jan-Pieter Paardekooper
  • Ikkoh Shimizu
  • Akio K. Inoue
  • Hannes Jensen
  • Genoveva Micheva
  • Sadegh Khochfar
  • Claudio Dalla Vecchia

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Original languageEnglish
Pages (from-to)78
JournalAstrophysical Journal
Issue number1
Publication statusPublished - 9 Feb 2017


Using four different suites of cosmological simulations, we generate synthetic spectra for galaxies with different Lyman-continuum escape fractions (f esc) at redshifts z≈ 7-9, in the rest-frame wavelength range relevant for the James Webb Space Telescope (JWST) NIRSpec instrument. By investigating the effects of realistic star formation histories and metallicity distributions on the EW(Hβ)-β diagram (previously proposed as a tool for identifying galaxies with very high f esc), we find that neither of these effects are likely to jeopardize the identification of galaxies with extreme Lyman-continuum leakage. Based on our models, we expect that essentially all z≈ 7{--}9 galaxies that exhibit rest-frame {EW}({{H}}β )≲ 30 Å to have {f}{esc}> 0.5. Incorrect assumptions concerning the ionizing fluxes of stellar populations or the dust properties of z> 6 galaxies can in principle bias the selection, but substantial model deficiencies of this type should at the same time be evident from offsets in the observed distribution of z> 6 galaxies in the EW(Hβ)-β diagram compared to the simulated distribution. Such offsets would thereby allow JWST/NIRSpec measurements of these observables to serve as input for further model refinement.

    Research areas

  • dark ages, reionization, first stars, galaxies: high-redshift, techniques: spectroscopic

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