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zELDA: fitting Lyman alpha line profiles using deep learning.
- Source :
- Monthly Notices of the Royal Astronomical Society; Mar2022, Vol. 510 Issue 3, p4525-4555, 31p
- Publication Year :
- 2022
-
Abstract
- We present zELDA (redshift Estimator for Line profiles of Distant Lyman Alpha emitters), an open source code to fit Lyman α (Ly α) line profiles. The main motivation is to provide the community with an easy to use and fast tool to analyse Ly α line profiles uniformly to improve the understating of Ly α emitting galaxies. zELDA is based on line profiles of the commonly used 'shell-model' pre-computed with the full Monte Carlo radiative transfer code LyaRT. Via interpolation between these spectra and the addition of noise, we assemble a suite of realistic Ly α spectra which we use to train a deep neural network.We show that the neural network can predict the model parameters to high accuracy (e.g. ≲ 0.34 dex H i column density for R ∼ 12 000) and thus allows for a significant speedup over existing fitting methods. As a proof of concept, we demonstrate the potential of zELDA by fitting 97 observed Ly α line profiles from the LASD data base. Comparing the fitted value with the measured systemic redshift of these sources, we find that Ly α determines their rest frame Ly α wavelength with a remarkable good accuracy of ∼0.3 Å (|$\sim 75\,\, {\rm km\, s}^{-1}$|). Comparing the predicted outflow properties and the observed Ly α luminosity and equivalent width, we find several possible trends. For example, we find an anticorrelation between the Ly α luminosity and the outflow neutral hydrogen column density, which might be explained by the radiative transfer process within galaxies. [ABSTRACT FROM AUTHOR]
- Subjects :
- RADIATIVE transfer
DEEP learning
SOURCE code
PROOF of concept
REDSHIFT
DATABASES
Subjects
Details
- Language :
- English
- ISSN :
- 00358711
- Volume :
- 510
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Publication Type :
- Academic Journal
- Accession number :
- 154976256
- Full Text :
- https://doi.org/10.1093/mnras/stab3554