Impact of redshift distribution uncertainties on Lyman-break galaxy cosmological parameter inference

Fuente: arXiv
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Main Authors: Petri, Francesco, Leistedt, Boris, Mortlock, Daniel J., Leja, Joel, Thorp, Stephen, Alsing, Justin, Peiris, Hiranya V., Deger, Sinan
Format: Preprint
Published: 2025
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author Petri, Francesco
Leistedt, Boris
Mortlock, Daniel J.
Leja, Joel
Thorp, Stephen
Alsing, Justin
Peiris, Hiranya V.
Deger, Sinan
author_facet Petri, Francesco
Leistedt, Boris
Mortlock, Daniel J.
Leja, Joel
Thorp, Stephen
Alsing, Justin
Peiris, Hiranya V.
Deger, Sinan
contents A significant number of Lyman-break galaxies (LBGs) with redshifts 3 < z < 5 are expected to be observed by the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). This will enable us to probe the universe at higher redshifts than is currently possible with cosmological galaxy clustering and weak lensing surveys. However, accurate inference of cosmological parameters requires precise knowledge of the redshift distributions of selected galaxies, where the number of faint objects expected from LSST alone will make spectroscopic based methods of determining these distributions extremely challenging. To overcome this difficulty, it may be possible to leverage the information in the large volume of photometric data alone to precisely infer these distributions. This could be facilitated using forward models, where in this paper we use stellar population synthesis (SPS) to estimate uncertainties on LBG redshift distributions for a 10 year LSST (LSSTY10) survey. We characterise some of the modelling uncertainties inherent to SPS by introducing a flexible parameterisation of the galaxy population prior, informed by observations of the galaxy stellar mass function (GSMF) and cosmic star formation density (CSFRD). These uncertainties are subsequently marginalised over and propagated to cosmological constraints in a Fisher forecast. Assuming a known dust attenuation model for LBGs, we forecast constraints on the sigma8 parameter comparable to Planck cosmic microwave background (CMB) constraints.
format Preprint
id arxiv_https___arxiv_org_abs_2506_06475
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Impact of redshift distribution uncertainties on Lyman-break galaxy cosmological parameter inference
Petri, Francesco
Leistedt, Boris
Mortlock, Daniel J.
Leja, Joel
Thorp, Stephen
Alsing, Justin
Peiris, Hiranya V.
Deger, Sinan
Cosmology and Nongalactic Astrophysics
A significant number of Lyman-break galaxies (LBGs) with redshifts 3 < z < 5 are expected to be observed by the upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). This will enable us to probe the universe at higher redshifts than is currently possible with cosmological galaxy clustering and weak lensing surveys. However, accurate inference of cosmological parameters requires precise knowledge of the redshift distributions of selected galaxies, where the number of faint objects expected from LSST alone will make spectroscopic based methods of determining these distributions extremely challenging. To overcome this difficulty, it may be possible to leverage the information in the large volume of photometric data alone to precisely infer these distributions. This could be facilitated using forward models, where in this paper we use stellar population synthesis (SPS) to estimate uncertainties on LBG redshift distributions for a 10 year LSST (LSSTY10) survey. We characterise some of the modelling uncertainties inherent to SPS by introducing a flexible parameterisation of the galaxy population prior, informed by observations of the galaxy stellar mass function (GSMF) and cosmic star formation density (CSFRD). These uncertainties are subsequently marginalised over and propagated to cosmological constraints in a Fisher forecast. Assuming a known dust attenuation model for LBGs, we forecast constraints on the sigma8 parameter comparable to Planck cosmic microwave background (CMB) constraints.
title Impact of redshift distribution uncertainties on Lyman-break galaxy cosmological parameter inference
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2506.06475