Hemispheric handedness in the Galactic synchrotron polarization foreground
arXiv:2003.14178 · doi:10.3847/2041-8213/ab974a
Abstract
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.
arXiv comment7 pages, 4 figures, 1 table, submitted to ApJL
References in corpus (29)
- HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
- Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Final Maps and Results
- Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
- An All-Sky Analysis of Polarization in the Microwave Background
- Signature of Gravity Waves in Polarization of the Microwave Background
- A Probe of Primordial Gravity Waves and Vorticity
- A New Model of the Galactic Magnetic Field
- Radio observational constraints on Galactic 3D-emission models
- Planck intermediate results. XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes
- Rotation Measures of Extragalactic Sources Behind the Southern Galactic Plane: New Insights into the Large-Scale Magnetic Field of the Inner Milky Way
- Planck 2018 results. XI. Polarized dust foregrounds
- Search for CP Violating Signature of Intergalactic Magnetic Helicity in the Gamma Ray Sky
- IMAGINE: A comprehensive view of the interstellar medium, Galactic magnetic fields and cosmic rays
- Observational constraints on models for the interstellar magnetic field in the Galactic disk
- Tensor calculus in polar coordinates using Jacobi polynomials
- Dust-polarization maps for local interstellar turbulence
- Primordial Magnetic Helicity Constraints from WMAP Nine-Year Data
- On the Detection of Magnetic Helicity
- Probing magnetic helicity with synchrotron radiation and Faraday rotation
- Faraday signature of magnetic helicity from reduced depolarization
- Can the observed E/B ratio for dust galactic foreground be explained by sub-Alfvenic turbulence?
- Constraining the regular Galactic Magnetic Field with the 5-year WMAP polarization measurements at 22 GHz
- Is there a left-handed magnetic field in the solar neighborhood? Exploring helical magnetic fields in the interstellar medium through dust polarization power spectra
- Magnetic field tomography, helical magnetic fields and Faraday depolarization
- Helicity detection of the astrophysical magnetic fields from radio emission statistics
- E and B polarizations from inhomogeneous and solar surface turbulence
- Imprints of magnetic power and helicity spectra on radio polarimetry statistics
- A global two-scale helicity proxy from -ambiguous solar magnetic fields
- The supernova-regulated ISM. IV. A comparison of simulated polarization with Planck observations