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Are Lyα emitters segregated in protoclusters regions?

Hough, Tomás; Gurung-López, Siddhartha; Orsi, Álvaro; Cora, Sofía A.; Lacey, Cedric G.; Baugh, Carlton M.

Are Lyα emitters segregated in protoclusters regions? Thumbnail


Tomás Hough

Siddhartha Gurung-López

Álvaro Orsi

Sofía A. Cora


The presence of neutral hydrogen in the inter-stellar medium (ISM) and inter-galactic medium (IGM) induces radiative transfer (RT) effects on Lyα photons which affect the observability of Lyα emitters (LAEs). We use the GALFORM semi-analytic model of galaxy formation and evolution to analyse how these effects shape the spatial distribution of LAEs with respect to Hα emitters (HAEs) around high density regions at high redshift. We find that when a large sample of protoclusters is considered, HAEs showing also Lyα emission (HAEs+LAEs) populate the same regions as those that do not display the Lyα line at z = 2.2. We compare against the protocluster USS1558-003, one of the most massive protoclusters located at z = 2.53. Our results indicate that the strong depletion of HAEs+LAEs present in the high density regions of USS1558-003 may be due to cosmic variance. We find that at z = 2.2 and z = 3.0, RT of the ISM produces a strong decline (30-50 per cent) of the clustering amplitude of HAEs+LAEs with respect to HAEs towards the protoclusters centre. At z = 5.7, given the early evolutionary state of protoclusters and galaxies, the clustering of HAEs+LAEs has a smaller variation (10-20 per cent) towards the protoclusters centre. Depending on the equivalent width and luminosity criteria of the emission-line galaxy sample, the IGM can have a mild or a null effect on galaxy properties and clustering in high density regions.


Hough, T., Gurung-López, S., Orsi, Á., Cora, S. A., Lacey, C. G., & Baugh, C. M. (2020). Are Lyα emitters segregated in protoclusters regions?. Monthly Notices of the Royal Astronomical Society, 499(2), 2104-2115.

Journal Article Type Article
Acceptance Date Sep 22, 2020
Online Publication Date Oct 21, 2020
Publication Date 2020-12
Deposit Date Oct 7, 2020
Publicly Available Date Oct 21, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 499
Issue 2
Pages 2104-2115


Published Journal Article (856 Kb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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