The Lyman-alpha signature of the first galaxies

Abstract

We present the Cosmic Lyman-$\alpha$ Transfer code (COLT), a massively parallel Monte-Carlo radiative transfer code, to simulate Lyman-$\alpha$ (Ly$\alpha$) resonant scattering through neutral hydrogen as a probe of the first galaxies. We explore the interaction of centrally produced Ly$\alpha$ radiation with the host galactic environment. Ly$\alpha$ photons emitted from the luminous starburst region escape with characteristic features in the line profile depending on the density distribution, ionization structure, and bulk velocity fields. For example, anisotropic ionization exhibits a tall peak close to line centre with a skewed tail that drops off gradually. Idealized models of first galaxies explore the effect of mass, anisotropic H II regions, and radiation pressure driven winds on Ly$\alpha$ observables. We employ mesh refinement to resolve critical structures. We also post-process an ab initio cosmological simulation and examine images captured at various escape distances within the 1 Mpc${}^3$ comoving volume. Finally, we discuss the emergent spectra and surface brightness profiles of these objects in the context of high-$z$ observations. The first galaxies will likely be observed through the red damping wing of the Ly$\alpha$ line. Observations will be biased toward galaxies with an intrinsic red peak located far from line centre that reside in extensive H II super bubbles, which allows Hubble flow to sufficiently redshift photons away from line centre and facilitate transmission through the intergalactic medium (IGM). Even with gravitational lensing to boost the luminosity this preliminary work indicates that Ly$\alpha$ emission from stellar clusters within haloes of $M_{\mathrm{vir}}<10^9{\mathrm{M}}_{\odot }$ is generally too faint to be detected by the James Webb Space Telescope (JWST).

28 pages, 22 figures, MNRAS, in press

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• Fast, Slow, Early, Late: Quenching Massive Galaxies at z~0.8
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• The Low-Redshift Lyman Continuum Survey. Unveiling the ISM properties of low-$z$ Lyman continuum emitters
• H-alpha emission in local galaxies: star formation, time variability and the diffuse ionized gas
• The THESAN project: ionizing escape fractions of reionization-era galaxies
• Lyman-$\alpha$ as a tracer of cosmic reionisation in the SPHINX radiation-hydrodynamics cosmological simulation
• The physics of Lyman-alpha escape from disc-like galaxies
• UV absorption lines and their potential for tracing the Lyman continuum escape fraction
• Deciphering Lyman-$\alpha$ Emission Deep into the Epoch of Reionisation
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• A systematic study of the escape of LyC and Ly$\alpha$ photons from star-forming, magnetized turbulent clouds
• GN-z11: The environment of an AGN at $z=$10.603
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• Ly-alpha Radiative Transfer: Monte-Carlo Simulation of the Wouthuysen-Field Effect
• Radiative effects during the assembly of direct collapse black holes
• Boosting Lya and HeII 1640A Line Fluxes from Pop III Galaxies: Stochastic IMF Sampling and Departures from Case-B
• On the Detection of Supermassive Primordial Stars. II. Blue Supergiants
• The THESAN-ZOOM project: Burst, quench, repeat -- unveiling the evolution of high-redshift galaxies along the star-forming main sequence
• Arepo-MCRT: Monte Carlo Radiation Hydrodynamics on a Moving Mesh
• Effects of Spatial Discretization in Lyman-alpha Line Radiation Transfer Simulations
• The cosmic web in Lyman-alpha emission
• Real and counterfeit cores: how feedback expands halos and disrupts tracers of inner gravitational potential in dwarf galaxies
• Photon leaking or very hard ionizing radiation? Unveiling the nature of heII-emitters using the softness diagram
• Lyman-$\alpha$ feedback prevails at Cosmic Dawn: Implications for the first galaxies, stars, and star clusters
• Ly-alpha Radiative Transfer: A Stokes Vector Approach to Ly-alpha Polarization
• The THESAN project: Lyman-alpha emitter luminosity function calibration
• Smoothed Particle Radiation Hydrodynamics: Two-Moment method with Local Eddington Tensor Closure
• On the effect of Lyman alpha trapping during the initial collapse of massive black hole seeds
• The THESAN-ZOOM project: central starbursts and inside-out quenching govern galaxy sizes in the early Universe
• Resonant-line radiative transfer within power-law density profiles
• Mapping the ionized gas of the metal-poor HII galaxy PHL 293B with MEGARA
• The Lyman $\alpha$ Reference Sample XIV: Lyman $\alpha$ imaging of 45 low redshift star-forming galaxies and inferences on global emission
• CMacIonize 2.0: a novel task-based approach to Monte Carlo radiation transfer
• Contribution of the first galaxies to the cosmic far-infrared/sub-millimeter background - I. Mean background level
• A public grid of radiative transfer simulations for Lyman-alpha and metal lines in idealised galactic outflows
• A Simulated Galaxy Laboratory: Exploring the Observational Effects on UV Spectral Absorption Line Measurements
• Lyman-alpha resonant-line radiative transfer in expanding media
• SEURAT: SPH scheme extended with ultraviolet line radiative transfer
• A Novel Solution for Resonant Scattering Using Self-Consistent Boundary Conditions