High redshift ΛCDM cosmology: To bin or not to bin?

Eoin Ó Colgáin; M. M. Sheikh-Jabbari; Rance Solomon

doi:10.1016/j.dark.2023.101216

High redshift ΛCDM cosmology: To bin or not to bin?

Eoin Ó Colgáin
, M. M. Sheikh-Jabbari
, Rance Solomon

Institute for Research for Fundamental Sciences
The Research Foundation of The State University of New York

Research output: Contribution to journal › Article › peer-review

27 Citations (Scopus)

Abstract

We construct observational Hubble H(z) and angular diameter distance D_A(z) mock data collected in redshift bins with baseline Planck ΛCDM input values, before fitting the ΛCDM model to study evolution of probability density functions (PDFs) of best fit cosmological parameters (H₀,Ω_m,Ω_k) across the bins. We find that PDF peaks only agree with the input parameters in low redshift (z≲1) bins for H(z) and D_A(z) constraints, and in all redshift bins when H(z) and D_A(z) constraints are combined. When input parameters are not recovered, we observe that PDFs exhibit non-Gaussian tails towards larger Ω_m values and shifts to (less pronounced) peaks at smaller Ω_m values. This flattening of the PDF is expected as H(z) and D_A(z) observations only constrain combinations of cosmological parameters at higher redshifts, so uniform PDFs are expected. Our analysis leaves us with a choice to bin high redshift data in the knowledge that it may be unlikely to recover Planck values, or conduct full sample analysis that biases ΛCDM inferences to the lower redshift Universe.

Original language	English
Article number	101216
Journal	Physics of the Dark Universe
Volume	40
DOIs	https://doi.org/10.1016/j.dark.2023.101216
Publication status	Published - May 2023

Keywords

Cosmology
Dark Energy

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10.1016/j.dark.2023.101216

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@article{0f708fc504854b9fa61fcf212f27f092,

title = "High redshift ΛCDM cosmology: To bin or not to bin?",

abstract = "We construct observational Hubble H(z) and angular diameter distance DA(z) mock data collected in redshift bins with baseline Planck ΛCDM input values, before fitting the ΛCDM model to study evolution of probability density functions (PDFs) of best fit cosmological parameters (H0,Ωm,Ωk) across the bins. We find that PDF peaks only agree with the input parameters in low redshift (z≲1) bins for H(z) and DA(z) constraints, and in all redshift bins when H(z) and DA(z) constraints are combined. When input parameters are not recovered, we observe that PDFs exhibit non-Gaussian tails towards larger Ωm values and shifts to (less pronounced) peaks at smaller Ωm values. This flattening of the PDF is expected as H(z) and DA(z) observations only constrain combinations of cosmological parameters at higher redshifts, so uniform PDFs are expected. Our analysis leaves us with a choice to bin high redshift data in the knowledge that it may be unlikely to recover Planck values, or conduct full sample analysis that biases ΛCDM inferences to the lower redshift Universe.",

keywords = "Cosmology, Dark Energy",

author = "\{{\'O} Colg{\'a}in\}, Eoin and Sheikh-Jabbari, \{M. M.\} and Rance Solomon",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = may,

doi = "10.1016/j.dark.2023.101216",

language = "English",

volume = "40",

journal = "Physics of the Dark Universe",

issn = "2212-6864",

}

TY - JOUR

T1 - High redshift ΛCDM cosmology

T2 - To bin or not to bin?

AU - Ó Colgáin, Eoin

AU - Sheikh-Jabbari, M. M.

AU - Solomon, Rance

PY - 2023/5

Y1 - 2023/5

N2 - We construct observational Hubble H(z) and angular diameter distance DA(z) mock data collected in redshift bins with baseline Planck ΛCDM input values, before fitting the ΛCDM model to study evolution of probability density functions (PDFs) of best fit cosmological parameters (H0,Ωm,Ωk) across the bins. We find that PDF peaks only agree with the input parameters in low redshift (z≲1) bins for H(z) and DA(z) constraints, and in all redshift bins when H(z) and DA(z) constraints are combined. When input parameters are not recovered, we observe that PDFs exhibit non-Gaussian tails towards larger Ωm values and shifts to (less pronounced) peaks at smaller Ωm values. This flattening of the PDF is expected as H(z) and DA(z) observations only constrain combinations of cosmological parameters at higher redshifts, so uniform PDFs are expected. Our analysis leaves us with a choice to bin high redshift data in the knowledge that it may be unlikely to recover Planck values, or conduct full sample analysis that biases ΛCDM inferences to the lower redshift Universe.

AB - We construct observational Hubble H(z) and angular diameter distance DA(z) mock data collected in redshift bins with baseline Planck ΛCDM input values, before fitting the ΛCDM model to study evolution of probability density functions (PDFs) of best fit cosmological parameters (H0,Ωm,Ωk) across the bins. We find that PDF peaks only agree with the input parameters in low redshift (z≲1) bins for H(z) and DA(z) constraints, and in all redshift bins when H(z) and DA(z) constraints are combined. When input parameters are not recovered, we observe that PDFs exhibit non-Gaussian tails towards larger Ωm values and shifts to (less pronounced) peaks at smaller Ωm values. This flattening of the PDF is expected as H(z) and DA(z) observations only constrain combinations of cosmological parameters at higher redshifts, so uniform PDFs are expected. Our analysis leaves us with a choice to bin high redshift data in the knowledge that it may be unlikely to recover Planck values, or conduct full sample analysis that biases ΛCDM inferences to the lower redshift Universe.

KW - Cosmology

KW - Dark Energy

UR - https://www.scopus.com/pages/publications/85151076724

U2 - 10.1016/j.dark.2023.101216

DO - 10.1016/j.dark.2023.101216

M3 - Article

AN - SCOPUS:85151076724

SN - 2212-6864

VL - 40

JO - Physics of the Dark Universe

JF - Physics of the Dark Universe

M1 - 101216

ER -

High redshift ΛCDM cosmology: To bin or not to bin?

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Keywords

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