On possible variation in the cosmological baryon fraction

Gilbert P. Holder; Kenneth M. Nollett; Alexander Van Engelen

doi:10.1088/0004-637X/716/2/907

On possible variation in the cosmological baryon fraction

Gilbert P. Holder, Kenneth M. Nollett, Alexander Van Engelen

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

42 Scopus citations

Abstract

The fraction of matter that is in the form of baryons or dark matter could have spatial fluctuations in the form of baryon-dark matter isocurvature fluctuations. We use big bang nucleosynthesis calculations compared with observed light-element abundances as well as galaxy cluster gas fractions to constrain cosmological variations in the baryon fraction. Light-element abundances constrain spatial variations to be less than 26%-27%, while a sample of "relaxed" galaxy clusters shows spatial variations in gas fractions less than 8%. Larger spatial variations could cause differential screening of the primary cosmic microwave background (CMB) anisotropies, leading to asymmetries in the fluctuations, and ease some tension with the halo-star ⁷Li abundance. We also show that fluctuations within our allowed bounds can lead to "B-mode" CMB polarization anisotropies at a non-negligible level.

Original language	English (US)
Pages (from-to)	907-913
Number of pages	7
Journal	Astrophysical Journal
Volume	716
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/716/2/907
State	Published - 2010
Externally published	Yes

Keywords

Cosmological parameters
Cosmology: miscellaneous
Galaxies: abundances
Galaxies: clusters: general
Large-scale structure of universe

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1088/0004-637X/716/2/907

Cite this

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title = "On possible variation in the cosmological baryon fraction",

abstract = "The fraction of matter that is in the form of baryons or dark matter could have spatial fluctuations in the form of baryon-dark matter isocurvature fluctuations. We use big bang nucleosynthesis calculations compared with observed light-element abundances as well as galaxy cluster gas fractions to constrain cosmological variations in the baryon fraction. Light-element abundances constrain spatial variations to be less than 26%-27%, while a sample of {"}relaxed{"} galaxy clusters shows spatial variations in gas fractions less than 8%. Larger spatial variations could cause differential screening of the primary cosmic microwave background (CMB) anisotropies, leading to asymmetries in the fluctuations, and ease some tension with the halo-star 7Li abundance. We also show that fluctuations within our allowed bounds can lead to {"}B-mode{"} CMB polarization anisotropies at a non-negligible level.",

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TY - JOUR

T1 - On possible variation in the cosmological baryon fraction

AU - Holder, Gilbert P.

AU - Nollett, Kenneth M.

AU - Van Engelen, Alexander

PY - 2010

Y1 - 2010

N2 - The fraction of matter that is in the form of baryons or dark matter could have spatial fluctuations in the form of baryon-dark matter isocurvature fluctuations. We use big bang nucleosynthesis calculations compared with observed light-element abundances as well as galaxy cluster gas fractions to constrain cosmological variations in the baryon fraction. Light-element abundances constrain spatial variations to be less than 26%-27%, while a sample of "relaxed" galaxy clusters shows spatial variations in gas fractions less than 8%. Larger spatial variations could cause differential screening of the primary cosmic microwave background (CMB) anisotropies, leading to asymmetries in the fluctuations, and ease some tension with the halo-star 7Li abundance. We also show that fluctuations within our allowed bounds can lead to "B-mode" CMB polarization anisotropies at a non-negligible level.

AB - The fraction of matter that is in the form of baryons or dark matter could have spatial fluctuations in the form of baryon-dark matter isocurvature fluctuations. We use big bang nucleosynthesis calculations compared with observed light-element abundances as well as galaxy cluster gas fractions to constrain cosmological variations in the baryon fraction. Light-element abundances constrain spatial variations to be less than 26%-27%, while a sample of "relaxed" galaxy clusters shows spatial variations in gas fractions less than 8%. Larger spatial variations could cause differential screening of the primary cosmic microwave background (CMB) anisotropies, leading to asymmetries in the fluctuations, and ease some tension with the halo-star 7Li abundance. We also show that fluctuations within our allowed bounds can lead to "B-mode" CMB polarization anisotropies at a non-negligible level.

KW - Cosmological parameters

KW - Cosmology: miscellaneous

KW - Galaxies: abundances

KW - Galaxies: clusters: general

KW - Large-scale structure of universe

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JO - Astrophysical Journal

JF - Astrophysical Journal

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ER -

On possible variation in the cosmological baryon fraction

Abstract

Keywords

ASJC Scopus subject areas

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