The Pitfalls of Using Lyman Alpha Damping Wings in High-z Galaxy Spectra to Measure the Intergalactic Neutral Hydrogen Fraction
Fuente:
arXiv
Guardado en:
| Autores principales: | , , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2025
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866910939972894720 |
|---|---|
| author | Huberty, Mason Scarlata, Claudia Hayes, Matthew J. Gazagnes, Simon |
| author_facet | Huberty, Mason Scarlata, Claudia Hayes, Matthew J. Gazagnes, Simon |
| contents | The Lyman Alpha damping wing is seen in absorption against the spectra of high-redshift galaxies. Modeling of this wing is a way to measure the volume neutral hydrogen fraction of the Universe, as well as to measure the strength of HI absorption in the form of a damped Lyα absorber (DLA). We use very high-quality ultraviolet spectra of low-z galaxies to create mock high-redshift, low-resolution spectra complete with a damping wing resulting from the IGM and HI absorption from local, dense gas to mimic current James Webb Space Telescope (JWST) observations of the early universe. The simulated spectra are used to test the ability to recover the "true" values of the column density of the DLA (N_DLA) and the volume neutral hydrogen fraction (x_HI) of the IGM through modified stellar continuum fitting. We find that the ability to recover the true values of N_DLA and x_HI simultaneously is compromised by degeneracies between these two parameters, and the spectral shape itself at low-resolution (R~100). The root mean squared error between the recovered and true column density of the DLAs is on the order of 1 dex. This error somewhat decreases with improved resolution (R~1000), but systematically underestimates N_DLA when Lyα emission is present in the mock spectra. The recovered values of x_HI are poorly constrained and do not improve substantially with the higher resolution. We recommend accounting for these sources of uncertainty and biases when using galaxies' Lyα damping wings to measure the intergalactic neutral hydrogen fraction. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_13899 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Pitfalls of Using Lyman Alpha Damping Wings in High-z Galaxy Spectra to Measure the Intergalactic Neutral Hydrogen Fraction Huberty, Mason Scarlata, Claudia Hayes, Matthew J. Gazagnes, Simon Astrophysics of Galaxies The Lyman Alpha damping wing is seen in absorption against the spectra of high-redshift galaxies. Modeling of this wing is a way to measure the volume neutral hydrogen fraction of the Universe, as well as to measure the strength of HI absorption in the form of a damped Lyα absorber (DLA). We use very high-quality ultraviolet spectra of low-z galaxies to create mock high-redshift, low-resolution spectra complete with a damping wing resulting from the IGM and HI absorption from local, dense gas to mimic current James Webb Space Telescope (JWST) observations of the early universe. The simulated spectra are used to test the ability to recover the "true" values of the column density of the DLA (N_DLA) and the volume neutral hydrogen fraction (x_HI) of the IGM through modified stellar continuum fitting. We find that the ability to recover the true values of N_DLA and x_HI simultaneously is compromised by degeneracies between these two parameters, and the spectral shape itself at low-resolution (R~100). The root mean squared error between the recovered and true column density of the DLAs is on the order of 1 dex. This error somewhat decreases with improved resolution (R~1000), but systematically underestimates N_DLA when Lyα emission is present in the mock spectra. The recovered values of x_HI are poorly constrained and do not improve substantially with the higher resolution. We recommend accounting for these sources of uncertainty and biases when using galaxies' Lyα damping wings to measure the intergalactic neutral hydrogen fraction. |
| title | The Pitfalls of Using Lyman Alpha Damping Wings in High-z Galaxy Spectra to Measure the Intergalactic Neutral Hydrogen Fraction |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2501.13899 |