Helicity in the large-scale Galactic magnetic field

被引：11

作者：

West, J. L. ^{[1
]}

Henriksen, R. N. ^{[2
]}

Ferriere, K. ^{[3
]}

Woodfinden, A. ^{[2
]}

Jaffe, T. ^{[4
]}

Gaensler, B. M. ^{[1
]}

Irwin, J. A. ^{[2
]}

机构：

[1] Univ Toronto, Dunlap Inst Astron & Astrophys, Toronto, ON M5S 3H4, Canada

[2] Queens Univ, Kingston, ON K7L 3N6, Canada

[3] Univ Toulouse, Inst Rech Astrophys & Planetol IRAP, CNRS, 9 Ave Colonel Roche,BP 44346, F-31028 Toulouse 4, France

[4] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2020年 / 499卷 / 03期

基金：

加拿大自然科学与工程研究理事会;

关键词：

magnetic fields; polarization; cosmic rays; radio continuum: ISM; ROTATION MEASURES; FARADAY-ROTATION; MILKY-WAY; DYNAMOS; PLANE; HALO; EMISSION; GALAXY;

D O I：

10.1093/mnras/staa3068

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We search for observational signatures of magnetic helicity in data from all-sky radio polarization surveys of the Milky Way Galaxy. Such a detection would help confirm the dynamo origin of the field and may provide new observational constraints for its shape. We compare our observational results to simulated observations for both a simple helical field, and for a more complex field that comes from a solution to the dynamo equation. Our simulated observations show that the large-scale helicity of a magnetic field is reflected in the large-scale structure of the fractional polarization derived from the observed synchrotron radiation and Faraday depth of the diffuse Galactic synchrotron emission. Comparing the models with the observations provides evidence for the presence of a quadrupolar magnetic field with a vertical component that is pointing away from the observer in both hemispheres of the Milky Way Galaxy. Since there is no reason to believe that the Galactic magnetic field is unusual when compared to other galaxies, this result provides further support for the dynamo origin of large-scale magnetic fields in galaxies.

引用

页码：3673 / 3689

页数：17

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