Modeling 237 Lyman-α spectra of the MUSE-Wide survey^⋆

Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029, 0315 Oslo, Norway
e-mail: maxbg@astro.uio.no

Received: 17 August 2017
Accepted: 20 September 2017

Abstract

We compare 237 Lyman-α (Lyα) spectra of the MUSE-Wide survey to a suite of radiative transfer simulations consisting of a central luminous source within a concentric, moving shell of neutral gas, and dust. This six parameter shell-model has been used numerously in previous studies, however, on significantly smaller data-sets. We find that the shell-model can reproduce the observed spectral shape very well – better than the also common “Gaussian-minus-Gaussian” model which we also fitted to the dataset. Specifically, we find that ~ 94% of the fits possess a goodness-of-fit value of p(χ²) > 0.1. The large number of spectra allows us to robustly characterize the shell-model parameter range, and consequently, the spectral shapes typical for realistic spectra. We find that the vast majority of the Lyα spectral shapes require an outflow and only ~ 5% are well-fitted through an inflowing shell. In addition, we find ~ 46% of the spectra to be consistent with a neutral hydrogen column density < 10¹⁷ cm^-2 – suggestive of a non-negligible fraction of continuum leakers in the MUSE-Wide sample. Furthermore, we correlate the spectral against the Lyα halo properties against each other but do not find any strong correlation.