Searching for Primordial Magnetic Fields with CMB B-modes
Was the primordial universe magnetized? The answer to this question would help explain the origin of micro-Gauss strength magnetic fields observed in galaxies. It is also of fundamental importance in developing a complete theory of the early universe. While there can be other signatures of cosmologi...
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ftdatacite:10.48550/arxiv.1801.08936 2023-05-15T18:23:19+02:00 Searching for Primordial Magnetic Fields with CMB B-modes Pogosian, Levon Zucca, Alex 2018 https://dx.doi.org/10.48550/arxiv.1801.08936 https://arxiv.org/abs/1801.08936 unknown arXiv https://dx.doi.org/10.1088/1361-6382/aac398 arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Cosmology and Nongalactic Astrophysics astro-ph.CO Astrophysics of Galaxies astro-ph.GA FOS Physical sciences article-journal Article ScholarlyArticle Text 2018 ftdatacite https://doi.org/10.48550/arxiv.1801.08936 https://doi.org/10.1088/1361-6382/aac398 2022-04-01T10:07:51Z Was the primordial universe magnetized? The answer to this question would help explain the origin of micro-Gauss strength magnetic fields observed in galaxies. It is also of fundamental importance in developing a complete theory of the early universe. While there can be other signatures of cosmological magnetic fields, a signature in the cosmic microwave background (CMB) would prove their primordial origin. The B-mode polarization of CMB is particularly promising in this regard because there are relatively few other sources of B-modes, and because the vortical modes sourced by the primordial magnetic field (PMF) survive diffusion damping up to a small fraction of the Silk length. At present, the Planck temperature and polarization spectra combined with the B-mode spectrum measured by the South Pole Telescope (SPT) constrain the PMF strength to be no more than $\sim 1$ nano-Gauss (nG). Because of the quartic scaling of the CMB anisotropy spectra with the PMF strength, this bound will not change by much even with the significantly better measurements of the B-mode spectrum by the Stage III and Stage IV CMB experiments. On the other hand, tightening the bound well below the $1$ nG threshold would rule out the purely primordial origin (requiring no dynamo action) of galactic fields. Considering Faraday rotation, which converts some of the E-modes into B-modes and scales linearly with the field strength, will help to achieve this goal. As we demonstrate, the upcoming experiments, such as SPT-3G and the Simons Observatory, will be sensitive to fields of $\sim 0.5$ nG strength thanks to the mode-coupling signature induced by Faraday rotation. A future Stage IV ground based experiment or a Space Probe will be capable of probing fields below $0.1$ nG, and would detect a scale-invariant PMF of $0.2$ nG strength without de-lensing or subtracting the galactic rotation measure. : 17 revtex pages, 3 figures, 2 tables; invited contribution to the Magnetic Fields at Cosmological Scales Focus issue of CQG; V2 matches the published version and includes a new figure, added discussion and references Text South pole DataCite Metadata Store (German National Library of Science and Technology) Faraday ENVELOPE(-64.256,-64.256,-65.246,-65.246) South Pole |
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DataCite Metadata Store (German National Library of Science and Technology) |
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Cosmology and Nongalactic Astrophysics astro-ph.CO Astrophysics of Galaxies astro-ph.GA FOS Physical sciences |
spellingShingle |
Cosmology and Nongalactic Astrophysics astro-ph.CO Astrophysics of Galaxies astro-ph.GA FOS Physical sciences Pogosian, Levon Zucca, Alex Searching for Primordial Magnetic Fields with CMB B-modes |
topic_facet |
Cosmology and Nongalactic Astrophysics astro-ph.CO Astrophysics of Galaxies astro-ph.GA FOS Physical sciences |
description |
Was the primordial universe magnetized? The answer to this question would help explain the origin of micro-Gauss strength magnetic fields observed in galaxies. It is also of fundamental importance in developing a complete theory of the early universe. While there can be other signatures of cosmological magnetic fields, a signature in the cosmic microwave background (CMB) would prove their primordial origin. The B-mode polarization of CMB is particularly promising in this regard because there are relatively few other sources of B-modes, and because the vortical modes sourced by the primordial magnetic field (PMF) survive diffusion damping up to a small fraction of the Silk length. At present, the Planck temperature and polarization spectra combined with the B-mode spectrum measured by the South Pole Telescope (SPT) constrain the PMF strength to be no more than $\sim 1$ nano-Gauss (nG). Because of the quartic scaling of the CMB anisotropy spectra with the PMF strength, this bound will not change by much even with the significantly better measurements of the B-mode spectrum by the Stage III and Stage IV CMB experiments. On the other hand, tightening the bound well below the $1$ nG threshold would rule out the purely primordial origin (requiring no dynamo action) of galactic fields. Considering Faraday rotation, which converts some of the E-modes into B-modes and scales linearly with the field strength, will help to achieve this goal. As we demonstrate, the upcoming experiments, such as SPT-3G and the Simons Observatory, will be sensitive to fields of $\sim 0.5$ nG strength thanks to the mode-coupling signature induced by Faraday rotation. A future Stage IV ground based experiment or a Space Probe will be capable of probing fields below $0.1$ nG, and would detect a scale-invariant PMF of $0.2$ nG strength without de-lensing or subtracting the galactic rotation measure. : 17 revtex pages, 3 figures, 2 tables; invited contribution to the Magnetic Fields at Cosmological Scales Focus issue of CQG; V2 matches the published version and includes a new figure, added discussion and references |
format |
Text |
author |
Pogosian, Levon Zucca, Alex |
author_facet |
Pogosian, Levon Zucca, Alex |
author_sort |
Pogosian, Levon |
title |
Searching for Primordial Magnetic Fields with CMB B-modes |
title_short |
Searching for Primordial Magnetic Fields with CMB B-modes |
title_full |
Searching for Primordial Magnetic Fields with CMB B-modes |
title_fullStr |
Searching for Primordial Magnetic Fields with CMB B-modes |
title_full_unstemmed |
Searching for Primordial Magnetic Fields with CMB B-modes |
title_sort |
searching for primordial magnetic fields with cmb b-modes |
publisher |
arXiv |
publishDate |
2018 |
url |
https://dx.doi.org/10.48550/arxiv.1801.08936 https://arxiv.org/abs/1801.08936 |
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ENVELOPE(-64.256,-64.256,-65.246,-65.246) |
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Faraday South Pole |
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Faraday South Pole |
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South pole |
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South pole |
op_relation |
https://dx.doi.org/10.1088/1361-6382/aac398 |
op_rights |
arXiv.org perpetual, non-exclusive license http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
op_doi |
https://doi.org/10.48550/arxiv.1801.08936 https://doi.org/10.1088/1361-6382/aac398 |
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1766202888880652288 |