Variations of Observed Lyman-α Spectra Shapes due to the Intergalactic Absorption

Abstract

Lyman-$\alpha$ (Ly$\alpha$) spectra provide insights into the small-scale structure and kinematics of neutral hydrogen (HI) within galaxies as well as the ionization state of the intergalactic medium (IGM). The former defines the intrinsic spectrum of a galaxy, which is modified by the latter. These two effects are degenerate. Using the IllustrisTNG100 simulation, we study the impact of the IGM on Ly$\alpha$ spectral shapes between $z\sim 0$ and $5$. We compute the distribution of the expected Ly$\alpha$ peaks and of the peak asymmetry for different intrinsic spectra, redshifts and large-scale environments. We find that the commonly used averaged transmission curves give an incorrect perception of the observed spectral properties. We show that the distributions of peak counts and asymmetry can lift the degeneracy between the intrinsic spectrum and the IGM absorption. For example, we expect a significant number of triple peaked Ly$\alpha$ spectra (up to 30% at $z\sim 3$) if the galaxies' HI distribution become more porous at higher redshift as predicted by cosmological simulations. We provide a public catalog of transmission curves to be used in future simulations and observations to allow a more realistic IGM treatment.

arXiv commentA reduced data set underlying this publication is available at https://zenodo.org/record/3832098

References in corpus (39)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• First results from the IllustrisTNG simulations: matter and galaxy clustering
• First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies
• First results from the IllustrisTNG simulations: the galaxy color bimodality
• First results from the IllustrisTNG simulations: A tale of two elements -- chemical evolution of magnesium and europium
• A model for cosmological simulations of galaxy formation physics
• A New Calculation of the Ionizing Background Spectrum and the Effects of HeII Reionization
• On the evolution of the HI column density distribution in cosmological simulations
• Diffuse Lyman Alpha Emitting Halos: A Generic Property of High Redshift Star Forming Galaxies
• Lyman Alpha Radiation From Collapsing Protogalaxies I: Characteristics of the Emergent Spectrum
• Extended Lyman alpha haloes around individual high-redshift galaxies revealed by MUSE
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Ly$\alpha$ emission from Green Peas: the role of circumgalactic gas density, covering, and kinematics
• Lyman Alpha Radiative Transfer in a Multi-Phase Medium
• Inferences on the Timeline of Reionization at z~8 From the KMOS Lens-Amplified Spectroscopic Survey
• Lyman-alpha spectral properties of five newly discovered Lyman continuum emitters
• Intergalactic Transmission and its Impact on the Lyα Line
• The Ly-alpha Properties of Faint Galaxies at z2-3 with Systemic Redshifts and Velocity Dispersions from Keck-MOSFIRE
• The Spectroscopic Properties of Lyα-Emitters at z $\approx$ 2.7: Escaping Gas and Photons from Faint Galaxies
• The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization
• Radiative Transfer Modeling of Lyman Alpha Emitters. I. Statistics of Spectra and Luminosity
• The Lyman alpha Reference Sample: II. HST imaging results, integrated properties and trends
• The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259
• Ionising the Intergalactic Medium by Star Clusters: The first empirical evidence
• The physics of Lyman-alpha escape from high-redshift galaxies
• Green Pea Galaxies Reveal Secrets of Ly$\alpha$ Escape
• The MUSE-Wide Survey: A first catalogue of 831 emission line galaxies
• The Sunburst Arc: Direct Lyman α escape observed in the brightest known lensed galaxy
• Ly$\alpha$ Spectra from Multiphase Outflows, and their Connection to Shell Models
• Lyman alpha Emitting Galaxies in the Nearby Universe
• Radiative Transfer Modeling of Lyman Alpha Emitters. II. New Effects in Galaxy Clustering
• Effect of the intergalactic environment on the observability of Ly-alpha emitters during reionization
• Spectroscopic properties of luminous Lyman-α emitters at $z\approx 6-7$ and comparison to the Lyman-break population
• A Model For Infall Around Virialized Halos
• Lyα emission from galaxies in the Epoch of Reionization
• The impact of Lyman-$\alpha$ radiative transfer on large-scale clustering in the Illustris simulation
• The imprint of cosmic ray driven outflow on Lyman-alpha spectra
• Radiative Transfer Distortions of Lyman-$\alpha$ Emitters: a New Fingers-of-God Damping in the Clustering in Redshift Space

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• The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics
• The THESAN project: Lyman-alpha emission and transmission during the Epoch of Reionization
• The X-SHOOTER Lyman-$\alpha$ survey at z=2 (XLS-z2) I: What makes a galaxy a Lyman-$\alpha$ emitter?
• Equivalent widths of Lyman $\alpha$ emitters in MUSE-Wide and MUSE-Deep
• IGM Transmission Bias for $z$ $\ge$ 2.9 Lyman Continuum Detected Galaxies
• Revisiting the Gas Kinematics in SSA22 Lyman-$\alpha$ Blob 1 with Radiative Transfer Modeling in a Multiphase, Clumpy Medium
• ZELDA: fitting Lyman-alpha line profiles using deep learning
• The cosmic web in Lyman-alpha emission
• Where Outflows Meet Inflows: Gas Kinematics in SSA22 Lyman-$\alpha$ Blob 2 Decoded by Advanced Radiative Transfer Modelling
• The THESAN project: Lyman-alpha emitter luminosity function calibration
• HETDEX Public Source Catalog 1 -- Stacking 50K Lyman Alpha Emitters
• Can galaxy evolution mimic cosmic reionization?
• Mapping reionization bubbles in the JWST era II: inferring the position and characteristic size of individual bubbles
• Prospects for detecting cosmic filaments in Lyman-alpha emission across redshifts $z=2-5$
• zELDA II: reconstruction of galactic Lyman-alpha spectra attenuated by the intergalactic medium using neural networks
• Double-Peaked Ly$\alpha$ Emission during Reionization Requires Nearby Voids and a Favorable Local Ionizing Background
• First statistical constraints on galactic scale outflows properties traced by their extended Mg II emission with MUSE