Improving Photometric Redshifts of Epoch of Reionization Galaxies: A New Empirical Transmission Curve with Neutral Hydrogen Damping Wing Ly<i>α</i> Absorption
Abstract We present a new analytical model for the attenuation to Epoch of Reionization (EoR) galaxies by proximate neutral hydrogen gas. Many galaxy spectra in the EoR taken by JWST have shown a flux deficit at wavelengths just redward of the Lyman break, and this has been regarded as resulting from Ly α damping wing absorption by the increasing amount of neutral hydrogen in the line of sight. However, previous attenuation models for the intergalactic medium (IGM) commonly used in photometric redshift template-fitting codes assume that the Lyman break is rather sharp, which leads to systematic overestimation of photometric redshifts at z > 7. In this Letter, we build and empirically calibrate a new attenuation model that takes the increased Ly α damping wing absorption into account. Our model consists of the canonical IGM absorption and an additional absorption component due to dense neutral hydrogen gas clouds proximate to the galaxy, and we derive the redshift evolution of H i column density of the proximate clouds by calibrating the model using CANUCS JWST observations. The resulting total transmission curve resolves the photometric redshift bias at z > 7, an improvement that is robust to the choice of template-fitting code, template set, and photometric catalog used. The new attenuation model can be easily implemented in existing template-fitting codes and significantly improves the photometric redshift performance in the EoR.
Authors
- Gaël Noirot
- Anishya Harshan (ORCID: https://orcid.org/0000-0001-9414-6382)
- Maruša Bradač (ORCID: https://orcid.org/0000-0001-5984-0395)
- Vladan Markov (ORCID: https://orcid.org/0000-0002-5694-6124)
- G. Desprez (ORCID: https://orcid.org/0000-0001-8325-1742)
- S. Paltani (ORCID: https://orcid.org/0000-0002-8108-9179)
- Adam Muzzin (ORCID: https://orcid.org/0000-0002-9330-9108)
- Chris J. Willott (ORCID: https://orcid.org/0000-0002-4201-7367)
- Ghassan T. E. Sarrouh (ORCID: https://orcid.org/0000-0001-8830-2166)
- F. Dubath (ORCID: https://orcid.org/0000-0002-6533-2810)
- Yoshihisa Asada (ORCID: https://orcid.org/0000-0003-3983-5438)
- Kartheik G. Iyer (ORCID: https://orcid.org/0000-0001-9298-3523)
- Marcin Sawicki (ORCID: https://orcid.org/0000-0002-7712-7857)
- Nicholas S. Martis (ORCID: https://orcid.org/0000-0003-3243-9969)
- Gabriel Brammer (ORCID: https://orcid.org/0000-0003-2680-005X)
Institutions
- University of Geneva (CH)
- Herzberg Institute of Astrophysics (CA)
- University of Copenhagen (DK)
- Space Telescope Science Institute (US)
- University of Ljubljana (SI)
- University of Groningen (NL)
- York University (CA)
- Kyoto University (JP)
- Université Bourgogne Franche-Comté (FR)
- Damien Foundation (BD)
- Saint Mary's University (CA)
- Columbia University (US)
- University of California, Davis (US)
Publication Details
- Journal
- The Astrophysical Journal Letters
- Published
- 2025-04-03
- DOI
- https://doi.org/10.3847/2041-8213/adc388
- Citations
- 16
- Primary Topic
- Galaxies: Formation, Evolution, Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 18.48
Funders
- National Aeronautics and Space Administration
- Canadian Foundation for AIDS Research
- Canarie
- Space Telescope Science Institute
- Alliance de recherche numérique du Canada
- Canadian Space Agency
- Natural Sciences and Engineering Research Council of Canada
- Japan Society for the Promotion of Science