Lyman-Alpha Emission in High-Redshift Galaxy Systems
Summary
Lyman-alpha emission, arising from the transition of neutral hydrogen atoms at rest-frame 121.6 nm, serves as a powerful tracer of the gas reservoirs, star-formation activity and large-scale structure in galaxy systems at redshifts beyond z ≈ 2. In these early epochs, the interplay between ionising radiation, cooling flows and dust attenuation shapes the spatial extent and morphology of Lyman-alpha nebulae, halos and blobs that envelop forming galaxies and quasars. Resonant scattering of Lyman-alpha photons in the circumgalactic and intergalactic media redistributes emission over tens to hundreds of kiloparsecs, while kinematic signatures encode outflows, inflows and gravitational motions within dark-matter haloes. Observations with integral-field spectrographs, narrowband imagers and intensity-mapping techniques have revealed diffuse filaments of Lyman-alpha emission tracing the cosmic web, as well as the clustering of emission around protoclusters and filaments. Together, these studies offer unique insights into the feeding and feedback processes that regulate galaxy growth, the topology of reionisation and the cosmic star-formation history.
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Lyman-Alpha Emission in High-Redshift Galaxy Systems publication trend
The graph below shows the total number of articles in lyman-alpha emission in high-redshift galaxy systems across all publications each year (not limited to Nature Index journals).
Technical terms
Lyman-alpha emission: Photon emission at 121.6 nm from hydrogen electron transitions.
High-redshift galaxy systems: Galaxies and their environments at z > 2, during early cosmic epochs.
Circumgalactic medium (CGM): Gas enveloping a galaxy, extending beyond its stellar disc.
Resonant scattering: Absorption and re-emission of photons at a characteristic resonance frequency, broadening spatial distribution.
Radiative transfer: Propagation and interaction of radiation with matter, including absorption, emission and scattering processes.
Cosmic web filaments: Large-scale, thread-like structures of dark matter and gas connecting galaxies and clusters.
References
- Median surface-brightness profiles of Lyman-α haloes in the MUSE Extremely Deep Field. Astronomy & Astrophysics (2024).
- ODIN: Where Do Lyα Blobs Live? Contextualizing Blob Environments within Large-scale Structure. The Astrophysical Journal (2023).
- The MUSE Extremely Deep Field: The cosmic web in emission at high redshift⋆. Astronomy & Astrophysics (2021).
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