Progress on cosmological magnetic fields

Vachaspati, Tanmay

doi:10.1088/1361-6633/ac03a9

Cited by 118 publications

(87 citation statements)

References 211 publications

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“…Note, however, that the magnetic field depends on gradients of Φ. Other possible scenarios may be found in [106], with the general conclusion that magnetic fields of up to ∼10 −11 G on scales of ∼10 kpc are possible [59].…”

Section: Post-inflationarymentioning

confidence: 96%

“…The seed magnetic fields of cosmological scenarios, i.e., the PMFs, are thought to be created by some major cosmological effect, such that they permeate the whole Universe. Without any claim to completeness (more details may be found in [58,59,86]), we list some of these possibilities below.…”

Section: Cosmological Scenariosmentioning

confidence: 99%

“…This twisted pattern or, more specifically, its handedness, can be measured by the quantity Q introduced in [277] (and summarized in [59]) as…”

Section: Analytical Description Of Propagation and Observablesmentioning

confidence: 99%

“…However, the uncertainties in the intrinsic source spectrum and EBL model might be unrealistic, as noted in refs. [58,59].…”

Section: Analyses Of Individual Sourcesmentioning

confidence: 99%

“…Given the distance scales involved in this type of study, it is probable that, on average, the pairs are formed in cosmic voids, which fill most of the volume of the Universe. Because magnetic fields in voids are virtually unaffected by structure formation, they provide a direct window into the early Universe and the magnetogenesis process (see, e.g., [55][56][57][58][59] for reviews). The absence of such fields would indicate that seed magnetic fields originated in astrophysical objects, and were subsequently amplified through dynamo processes until they reached present-day levels of ∼1 µG in galaxies [52,57].…”

Section: Introductionmentioning

confidence: 99%

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The Gamma-ray Window to Intergalactic Magnetism

Batista

Saveliev

2021

Universe

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One of the most promising ways to probe intergalactic magnetic fields (IGMFs) is through gamma rays produced in electromagnetic cascades initiated by high-energy gamma rays or cosmic rays in the intergalactic space. Because the charged component of the cascade is sensitive to magnetic fields, gamma-ray observations of distant objects such as blazars can be used to constrain IGMF properties. Ground-based and space-borne gamma-ray telescopes deliver spectral, temporal, and angular information of high-energy gamma-ray sources, which carries imprints of the intervening magnetic fields. This provides insights into the nature of the processes that led to the creation of the first magnetic fields and into the phenomena that impacted their evolution. Here we provide a detailed description of how gamma-ray observations can be used to probe cosmic magnetism. We review the current status of this topic and discuss the prospects for measuring IGMFs with the next generation of gamma-ray observatories.

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Section: Post-inflationarymentioning

confidence: 96%

Section: Cosmological Scenariosmentioning

confidence: 99%

“…This twisted pattern or, more specifically, its handedness, can be measured by the quantity Q introduced in [277] (and summarized in [59]) as…”

Section: Analytical Description Of Propagation and Observablesmentioning

confidence: 99%

“…However, the uncertainties in the intrinsic source spectrum and EBL model might be unrealistic, as noted in refs. [58,59].…”

Section: Analyses Of Individual Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Gamma-ray Window to Intergalactic Magnetism

Batista

Saveliev

2021

Universe

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Kibble mechanism for electroweak magnetic monopoles and magnetic fields

Patel

Vachaspati

2022

J. High Energ. Phys.

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The vacuum manifold of the standard electroweak model is a three-sphere when one considers homogeneous Higgs field configurations. For inhomogeneous configurations we argue that the vacuum manifold is the Hopf fibered three sphere and that this viewpoint leads to general criteria to detect electroweak monopoles and Z-strings. We extend the Kibble mechanism to study the formation of electroweak monopoles and strings during electroweak symmetry breaking. The distribution of magnetic monopoles produces magnetic fields that have a spectrum Bλ ∝ λ−2, where λ is a smearing length scale. Even as the magnetic monopoles annihilate due to the confining Z-strings, the magnetic field evolves with the turbulent plasma and may be relevant for cosmological observations.

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Constraints on axions from cosmic distance measurements

Buen-Abad

Fan

Sun

2022

J. High Energ. Phys.

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Axion couplings to photons could induce photon-axion conversion in the presence of magnetic fields in the Universe. This conversion could impact various cosmic distance measurements, such as luminosity distances to type Ia supernovae and angular distances to galaxy clusters, in different ways. In this paper we consider different combinations of the most up-to-date distance measurements to constrain the axion-photon coupling. Employing the conservative cell magnetic field model for the magnetic fields in the intergalactic medium (IGM) and ignoring the conversion in the intracluster medium (ICM), we find the upper bounds on axion-photon couplings to be around 5×10−12 (nG/B) $$ \sqrt{\mathrm{Mpc}/s} $$ Mpc / s GeV–1 for axion masses ma below 10−13 eV, where B is the strength of the IGM magnetic field, and s is the comoving size of the magnetic domains. When including the conversion in the ICM, the upper bound is lowered and could reach 5 × 10−13 GeV−1 for ma< 5 × 10−12 eV. While this stronger bound depends on the ICM modeling, it is independent of the strength of the IGM magnetic field, for which there is no direct evidence yet. These constraints could be placed on firmer footing with an enhanced understanding and control of the astrophysical uncertainties associated with the IGM and ICM. All the bounds are determined by the shape of the Hubble rate as a function of redshift reconstructable from various distance measurements, and insensitive to today’s Hubble rate, of which there is a tension between early and late cosmological measurements. As an appendix, we discuss the model building challenges of the use of photon-axion conversion to make type Ia supernovae brighter to alleviate the Hubble problem/crisis.

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Progress on cosmological magnetic fields

Cited by 118 publications

References 211 publications

The Gamma-ray Window to Intergalactic Magnetism

The Gamma-ray Window to Intergalactic Magnetism

Kibble mechanism for electroweak magnetic monopoles and magnetic fields

Constraints on axions from cosmic distance measurements

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