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THE SPECTRAL EVOLUTION OF THE FIRST GALAXIES. II. SPECTRAL SIGNATURES OF LYMAN CONTINUUM LEAKAGE FROM GALAXIES IN THE REIONIZATION EPOCH

Journal Article · · Astrophysical Journal
;  [1]
  1. The Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-106 91 Stockholm (Sweden)
The fraction of ionizing photons that escape (f{sub esc}) from z ∼> 6 galaxies is an important parameter for assessing the role of these objects in the reionization of the universe, but the opacity of the intergalactic medium precludes a direct measurement of f{sub esc} for individual galaxies at these epochs. We argue that since f{sub esc} regulates the impact of nebular emission on the spectra of galaxies, it should nonetheless be possible to indirectly probe f{sub esc} well into the reionization epoch. As a first step, we demonstrate that by combining measurements of the rest-frame UV slope β with the equivalent width of the Hβ emission line, galaxies with very high Lyman continuum escape fractions (f{sub esc} ≥ 0.5) should be identifiable up to z ≈ 9 through spectroscopy with the upcoming James Webb Space Telescope (JWST). By targeting strongly lensed galaxies behind low-redshift galaxy clusters, JWST spectra of sufficiently good quality can be obtained for M{sub 1500} ∼< –16.0 galaxies at z ≈ 7 and for M{sub 1500} ∼< –17.5 galaxies at z ≈ 9. Dust-obscured star formation may complicate the analysis, but supporting observations with ALMA or the planned SPICA mission may provide useful constraints on this effect.
OSTI ID:
22270679
Journal Information:
Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 777; ISSN ASJOAB; ISSN 0004-637X
Country of Publication:
United States
Language:
English