How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail
We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, Neff. Constraints from current data combination of Wilkinson Microwave Anisotropy P...
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ftdatacite:10.48550/arxiv.1104.2333 2023-05-15T18:22:49+02:00 How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail Hou, Zhen Keisler, Ryan Knox, Lloyd Millea, Marius Reichardt, Christian 2011 https://dx.doi.org/10.48550/arxiv.1104.2333 https://arxiv.org/abs/1104.2333 unknown arXiv https://dx.doi.org/10.1103/physrevd.87.083008 arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences article-journal Article ScholarlyArticle Text 2011 ftdatacite https://doi.org/10.48550/arxiv.1104.2333 https://doi.org/10.1103/physrevd.87.083008 2022-04-01T14:38:34Z We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, Neff. Constraints from current data combination of Wilkinson Microwave Anisotropy Probe (WMAP) and South Pole Telescope (SPT) are almost entirely due to the impact of the neutrinos on the expansion rate, and how those changes to the expansion rate alter the ratio of the photon diffusion scale to the sound horizon scale at recombination. We demonstrate that very little of the constraining power comes from the early Integrated Sachs-Wolfe (ISW) effect, and also provide a first determination of the amplitude of the early ISW effect. Varying the fraction of baryonic mass in Helium, Yp, also changes the ratio of damping to sound-horizon scales. We discuss the physical effects that prevent the resulting near-degeneracy between Neff and Yp from being a complete one. Examining light element abundance measurements, we see no significant evidence for evolution of Neff and the baryon-to-photon ratio from the epoch of big bang nucleosynthesis to decoupling. Finally, we consider measurements of the distance-redshift relation at low to intermediate redshifts and their implications for the value of Neff. : 11 pages. Replaced version extends our discussion of origin of constraints and updates for current data, submitted to PRD Text South pole DataCite Metadata Store (German National Library of Science and Technology) South Pole Wilkinson ENVELOPE(-66.200,-66.200,-66.817,-66.817) |
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DataCite Metadata Store (German National Library of Science and Technology) |
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topic |
Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences |
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Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences Hou, Zhen Keisler, Ryan Knox, Lloyd Millea, Marius Reichardt, Christian How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
topic_facet |
Cosmology and Nongalactic Astrophysics astro-ph.CO FOS Physical sciences |
description |
We explore the physical origin and robustness of constraints on the energy density in relativistic species prior to and during recombination, often expressed as constraints on an effective number of neutrino species, Neff. Constraints from current data combination of Wilkinson Microwave Anisotropy Probe (WMAP) and South Pole Telescope (SPT) are almost entirely due to the impact of the neutrinos on the expansion rate, and how those changes to the expansion rate alter the ratio of the photon diffusion scale to the sound horizon scale at recombination. We demonstrate that very little of the constraining power comes from the early Integrated Sachs-Wolfe (ISW) effect, and also provide a first determination of the amplitude of the early ISW effect. Varying the fraction of baryonic mass in Helium, Yp, also changes the ratio of damping to sound-horizon scales. We discuss the physical effects that prevent the resulting near-degeneracy between Neff and Yp from being a complete one. Examining light element abundance measurements, we see no significant evidence for evolution of Neff and the baryon-to-photon ratio from the epoch of big bang nucleosynthesis to decoupling. Finally, we consider measurements of the distance-redshift relation at low to intermediate redshifts and their implications for the value of Neff. : 11 pages. Replaced version extends our discussion of origin of constraints and updates for current data, submitted to PRD |
format |
Text |
author |
Hou, Zhen Keisler, Ryan Knox, Lloyd Millea, Marius Reichardt, Christian |
author_facet |
Hou, Zhen Keisler, Ryan Knox, Lloyd Millea, Marius Reichardt, Christian |
author_sort |
Hou, Zhen |
title |
How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
title_short |
How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
title_full |
How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
title_fullStr |
How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
title_full_unstemmed |
How Massless Neutrinos Affect the Cosmic Microwave Background Damping Tail |
title_sort |
how massless neutrinos affect the cosmic microwave background damping tail |
publisher |
arXiv |
publishDate |
2011 |
url |
https://dx.doi.org/10.48550/arxiv.1104.2333 https://arxiv.org/abs/1104.2333 |
long_lat |
ENVELOPE(-66.200,-66.200,-66.817,-66.817) |
geographic |
South Pole Wilkinson |
geographic_facet |
South Pole Wilkinson |
genre |
South pole |
genre_facet |
South pole |
op_relation |
https://dx.doi.org/10.1103/physrevd.87.083008 |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.1104.2333 https://doi.org/10.1103/physrevd.87.083008 |
_version_ |
1766202234380484608 |