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A circular polarimeter for the Cosmic Microwave Background

A primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution o...

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Autor principal: Giovannini, Massimo
Lenguaje:eng
Publicado: 2010
Materias:
Acceso en línea:https://dx.doi.org/10.1088/1475-7516/2010/08/028
http://cds.cern.ch/record/1256503
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author Giovannini, Massimo
author_facet Giovannini, Massimo
author_sort Giovannini, Massimo
collection CERN
description A primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution of the temperature fluctuations as well as the equations for the linear polarization. The observed values of the temperature and polarization angular power spectra are used to infer constraints on the amplitude and on the spectral slope of the primordial V-mode. Prior to photon decoupling magnetic fields play the role of polarimeters insofar as they unveil the circular dichroism by coupling the V-mode power spectrum to the remaining brightness perturbations. Conversely, for angular scales ranging between 4 deg and 10 deg the joined bounds on the magnitude of circular polarization and on the magnetic field intensity suggest that direct limits on the V-mode power spectrum in the range of 0.01 mK could directly rule out pre-decoupling magnetic fields in the range of 10-100 nG. The frequency dependence of the signal is located, for the present purposes, in the GHz range.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2010
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spelling cern-12565032023-03-14T19:10:30Zdoi:10.1088/1475-7516/2010/08/028http://cds.cern.ch/record/1256503engGiovannini, MassimoA circular polarimeter for the Cosmic Microwave BackgroundAstrophysics and AstronomyA primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution of the temperature fluctuations as well as the equations for the linear polarization. The observed values of the temperature and polarization angular power spectra are used to infer constraints on the amplitude and on the spectral slope of the primordial V-mode. Prior to photon decoupling magnetic fields play the role of polarimeters insofar as they unveil the circular dichroism by coupling the V-mode power spectrum to the remaining brightness perturbations. Conversely, for angular scales ranging between 4 deg and 10 deg the joined bounds on the magnitude of circular polarization and on the magnetic field intensity suggest that direct limits on the V-mode power spectrum in the range of 0.01 mK could directly rule out pre-decoupling magnetic fields in the range of 10-100 nG. The frequency dependence of the signal is located, for the present purposes, in the GHz range.A primordial degree of circular polarization of the Cosmic Microwave Background is not observationally excluded. The hypothesis of primordial dichroism can be quantitatively falsified if the plasma is magnetized prior to photon decoupling since the initial V-mode polarization affects the evolution of the temperature fluctuations as well as the equations for the linear polarization. The observed values of the temperature and polarization angular power spectra are used to infer constraints on the amplitude and on the spectral slope of the primordial V-mode. Prior to photon decoupling magnetic fields play the role of polarimeters insofar as they unveil the circular dichroism by coupling the V-mode power spectrum to the remaining brightness perturbations. Conversely, for angular scales ranging between 4 deg and 10 deg the joined bounds on the magnitude of circular polarization and on the magnetic field intensity suggest that direct limits on the V-mode power spectrum in the range of 0.01 mK could directly rule out pre-decoupling magnetic fields in the range of 10-100 nG. The frequency dependence of the signal is located, for the present purposes, in the GHz range.arXiv:1003.5892CERN-PH-TH-2010-067CERN-PH-TH-2010-067oai:cds.cern.ch:12565032010-03-31
spellingShingle Astrophysics and Astronomy
Giovannini, Massimo
A circular polarimeter for the Cosmic Microwave Background
title A circular polarimeter for the Cosmic Microwave Background
title_full A circular polarimeter for the Cosmic Microwave Background
title_fullStr A circular polarimeter for the Cosmic Microwave Background
title_full_unstemmed A circular polarimeter for the Cosmic Microwave Background
title_short A circular polarimeter for the Cosmic Microwave Background
title_sort circular polarimeter for the cosmic microwave background
topic Astrophysics and Astronomy
url https://dx.doi.org/10.1088/1475-7516/2010/08/028
http://cds.cern.ch/record/1256503
work_keys_str_mv AT giovanninimassimo acircularpolarimeterforthecosmicmicrowavebackground
AT giovanninimassimo circularpolarimeterforthecosmicmicrowavebackground