Hemispheric Handedness in the Galactic Synchrotron Polarization Foreground

Brandenburg, Axel (author): Stockholms universitet,KTH,Nordic Institute for Theoretical Physics NORDITA,KUniv Colorado, JILA, Boulder, CO 80303 USA.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA.;Carnegie Mellon Univ, McWilliams Ctr Cosmol, Pittsburgh, PA 15213 USA.;Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA.,Nordiska institutet för teoretisk fysik (Nordita),Institutionen för astronomi,University of Colorado, USA; Carnegie Mellon University, USA

Brueggen, Marcus (author): Univ Hamburg, Hamburger Sternwarte, Gojenbergsweg 112, D-21029 Hamburg, Germany.

(creator_code:org_t)

2020-06-11
2020
English.
In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 896:1

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Abstract Subject headings

The large-scale magnetic field of the Milky Way is thought to be created by an alpha omega dynamo, which implies that it should have opposite handedness north and south of the Galactic midplane. Here we attempt to detect a variation in handedness using polarization data from the Wilkinson Microwave Anisotropy Probe. Previous analyzes of the parity-even and parity-odd parts of linear polarization of the global dust and synchrotron emission have focused on quadratic correlations in spectral space of, and between, these two components. Here, by contrast, we analyze the parity-odd polarization itself and show that it has, on average, opposite signs in northern and southern Galactic hemispheres. Comparison with a Galactic mean-field dynamo model shows broad qualitative agreement and reveals that the sign of the observed hemispheric dependence of the azimuthally averaged parity-odd polarization is not determined by the sign of alpha, but by the sense of differential rotation.

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

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