The Impact of an Extra Background of Relativistic Particles on the Cosmological Parameters derived from Microwave Background Anisotropies

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dc.creatorBowen, R.
dc.creatorHansen, S. H.
dc.creatorMelchiorri, A.
dc.creatorSilk, J.
dc.creatorTrotta, R.
dc.date2001-10-30
dc.date.accessioned2026-07-07T10:51:20Z
dc.date.available2026-07-07T10:51:20Z
dc.descriptionRecent estimates of cosmological parameters derived from Cosmic Microwave Background (CMB) anisotropies are based on the assumption that we know the precise amount of energy density in relativistic particles in the universe, $ω_{rel}$, at all times. There are, however, many possible mechanisms that can undermine this assumption. In this paper we investigate the effect that removing this assumption has on the determination of the various cosmological parameters. We obtain fairly general bounds on the redshift of equality, $z_{eq}= ω_{m}/ω_{rel}=3100_{-400}^{+600}$. We show that $ω_{rel}$ is nearly degenerate with the amount of energy in matter, $ω_m$, and that its inclusion in CMB parameter estimation also affects the present constraints on other parameters such as the curvature or the scalar spectral index of primordial fluctuations. This degeneracy has the effect of limiting the precision of parameter estimation from the MAP satellite, but it can be broken by measurements on smaller scales such as those provided by the Planck satellite mission.
dc.description9 pages, 6 figures, Submitted to MNRAS. High resolution colour pictures can be obtained on request from the authors
dc.identifierhttps://arxiv.org/abs/astro-ph/0110636
dc.identifierhttp://arxiv.org/abs/astro-ph/0110636
dc.identifierMon.Not.Roy.Astron.Soc.334:760,2002
dc.identifierdoi:10.1046/j.1365-8711.2002.05570.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/184785
dc.subjectAstrophysics
dc.subjectHigh Energy Physics - Phenomenology
dc.titleThe Impact of an Extra Background of Relativistic Particles on the Cosmological Parameters derived from Microwave Background Anisotropies
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