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Multiwavelength consensus of large-scale linear bias

Pan, Hengxing; Obreschkow, Danail; Howlett, Cullan; Lagos, Claudia del P; Elahi, Pascal J; Baugh, Carlton; Gonzalez-Perez, Violeta

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Hengxing Pan

Danail Obreschkow

Cullan Howlett

Claudia del P Lagos

Pascal J Elahi

Violeta Gonzalez-Perez


We model the large-scale linear galaxy bias bg(x, z) as a function of redshift z and observed absolute magnitude threshold x for broad-band continuum emission from the far-infrared to ultraviolet, as well as for prominent emission lines, such as the H α, H β, Ly a, and [O II] lines. The modelling relies on the semi-analytic galaxy formation model GALFORM, run on the state-of-the-art N-body simulation SURFS with the Planck 2015 cosmology. We find that both the differential bias at observed absolute magnitude x and the cumulative bias for magnitudes brighter than x can be fitted with a five-parameter model: bg(x, z) = a + b(1 + z)e(1 + exp [(x − c)d]). We also find that the bias for the continuum bands follows a very similar form regardless of wavelength due to the mixing of star-forming and quiescent galaxies in a magnitude-limited survey. Differences in bias only become apparent when an additional colour separation is included, which suggest extensions to this work could look at different colours at fixed magnitude limits. We test our fitting formula against observations, finding reasonable agreement with some measurements within 1σ statistical uncertainties, and highlighting areas of improvement. We provide the fitting parameters for various continuum bands, emission lines, and intrinsic galaxy properties, enabling a quick estimation of the linear bias in any typical survey of large-scale structure.


Pan, H., Obreschkow, D., Howlett, C., Lagos, C. D. P., Elahi, P. J., Baugh, C., & Gonzalez-Perez, V. (2020). Multiwavelength consensus of large-scale linear bias. Monthly Notices of the Royal Astronomical Society, 493(1), 747-764.

Journal Article Type Article
Acceptance Date Jan 5, 2020
Online Publication Date Jan 25, 2020
Publication Date Mar 31, 2020
Deposit Date Mar 25, 2020
Publicly Available Date Mar 25, 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 493
Issue 1
Pages 747-764


Published Journal Article (6.2 Mb)

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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