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16643

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DataCite Commons2023-04-21 更新2025-04-15 收录
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http://esdcdoi.esac.esa.int/doi/html/data/astronomy/hst/16643.html
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Ly-alpha (LyA) is the strongest feature in the rest-frame far-UV emission-line spectra of galaxies and our most reliable indicator of leaking ionizing photons. However comma the intergalactic medium is increasingly neutral at higher redshifts comma attenuating both ionizing and LyA emission from galaxies within the epoch of reionization (EoR). Additionally comma LyA provides a limited tracer of the escaping ionizing radiation as it probes the low-ionization gas properties (close to the H-ionizing edge at 912 A comma 13.6 eV) comma while the ionizing continuum peaks at significantly higher energies (500 A or 24.6 eV). Higher-energy photons significantly contribute to reionizing the neutral hydrogen as they can each ionize 2 H atoms comma nevertheless comma their escape-fraction is dramatically underestimated by the standard measurement of the ionizing photon escape at 900 A. To map the escape of ionizing photons across the full ionizing continuum for the first time comma we propose to combine archival and new HST-COS G130M+G160M observations of the LyA and C IV emission profiles of 10 nearby extreme UV emission-line galaxies. LyA and C IV probe different ionization stages (low and high comma respectively) of the gas comma and thus different energies of ionizing photons. Therefore comma these high-resolution observations will enable us to determine the column densities of the low and high ionization gas comma estimate the fraction of both low- and high-energy photons escaping EoR systems comma and provide reliable diagnostics from emission line features observable in the early universe comma which is critical for interpreting FUV emission-line features in forthcoming spectra of high-z galaxies with JWST.
提供机构:
European Space Agency
创建时间:
2023-04-21
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