Can non-Gaussian cosmological models explain the WMAP high optical depth for reionization?
Identifieur interne : 000359 ( Main/Exploration ); précédent : 000358; suivant : 000360Can non-Gaussian cosmological models explain the WMAP high optical depth for reionization?
Auteurs : Xuelei Chen [États-Unis] ; Asantha Cooray [États-Unis] ; Naoki Yoshida [Japon] ; Naoshi Sugiyama [Japon]Source :
- Monthly Notices of the Royal Astronomical Society [ 0035-8711 ] ; 2003-12-11.
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Abstract
The first-year Wilkinson Microwave Anisotropy Probe data suggest a high optical depth for Thomson scattering of 0.17 ± 0.04, implying that the Universe was reionized at an earlier epoch than previously expected. Such early reionization is likely to be caused by ultraviolet (UV) photons from first stars, but it appears that the observed high optical depth can be reconciled within the standard structure formation model only if star formation in the early Universe was extremely efficient. With normal star formation efficiencies, cosmological models with non-Gaussian density fluctuations may circumvent this conflict as high density peaks collapse at an earlier epoch than in models with Gaussian fluctuations. We study cosmic reionization in non-Gaussian models and explore to what extent, within available constraints, non-Gaussianities affect the reionization history. For mild non-Gaussian fluctuations at redshifts of 30 to 50, the increase in optical depth remains at a level of a few per cent and appears unlikely to aid significantly in explaining the measured high optical depth. On the other hand, within available observational constraints, increasing the non-Gaussian nature of density fluctuations can easily reproduce the optical depth and may remain viable in underlying models of non-Gaussianity with a scale-dependence.
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DOI: 10.1111/j.1365-2966.2003.07316.x
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Soc.</title><idno type="ISSN">0035-8711</idno><idno type="eISSN">1365-2966</idno><imprint><publisher>Blackwell Science Ltd</publisher><pubPlace>Oxford, UK</pubPlace><date type="published" when="2003-12-11">2003-12-11</date><biblScope unit="volume">346</biblScope><biblScope unit="issue">3</biblScope><biblScope unit="page" from="L31">L31</biblScope><biblScope unit="page" to="L35">L35</biblScope></imprint><idno type="ISSN">0035-8711</idno></series><idno type="istex">302F99E9FE675898AA68D39F95813D9BAA8DD9A0</idno><idno type="DOI">10.1111/j.1365-2966.2003.07316.x</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0035-8711</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>cosmic microwave background</term><term>cosmology: observations</term><term>cosmology: theory</term><term>large-scale structure of Universe</term></keywords></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract">The first-year Wilkinson Microwave Anisotropy Probe data suggest a high optical depth for Thomson scattering of 0.17 ± 0.04, implying that the Universe was reionized at an earlier epoch than previously expected. Such early reionization is likely to be caused by ultraviolet (UV) photons from first stars, but it appears that the observed high optical depth can be reconciled within the standard structure formation model only if star formation in the early Universe was extremely efficient. With normal star formation efficiencies, cosmological models with non-Gaussian density fluctuations may circumvent this conflict as high density peaks collapse at an earlier epoch than in models with Gaussian fluctuations. We study cosmic reionization in non-Gaussian models and explore to what extent, within available constraints, non-Gaussianities affect the reionization history. For mild non-Gaussian fluctuations at redshifts of 30 to 50, the increase in optical depth remains at a level of a few per cent and appears unlikely to aid significantly in explaining the measured high optical depth. On the other hand, within available observational constraints, increasing the non-Gaussian nature of density fluctuations can easily reproduce the optical depth and may remain viable in underlying models of non-Gaussianity with a scale-dependence.</div></front></TEI><affiliations><list><country><li>Japon</li><li>États-Unis</li></country><region><li>Californie</li><li>Région de Kantō</li></region><settlement><li>Tokyo</li></settlement></list><tree><country name="États-Unis"><region name="Californie"><name sortKey="Chen, Xuelei" sort="Chen, Xuelei" uniqKey="Chen X" first="Xuelei" last="Chen">Xuelei Chen</name></region><name sortKey="Cooray, Asantha" sort="Cooray, Asantha" uniqKey="Cooray A" first="Asantha" last="Cooray">Asantha Cooray</name><name sortKey="Cooray, Asantha" sort="Cooray, Asantha" uniqKey="Cooray A" first="Asantha" last="Cooray">Asantha Cooray</name></country><country name="Japon"><region name="Région de Kantō"><name sortKey="Yoshida, Naoki" sort="Yoshida, Naoki" uniqKey="Yoshida N" first="Naoki" last="Yoshida">Naoki Yoshida</name></region><name sortKey="Sugiyama, Naoshi" sort="Sugiyama, Naoshi" uniqKey="Sugiyama N" first="Naoshi" last="Sugiyama">Naoshi Sugiyama</name></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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