Magnetic field vector maps of nearby spiral galaxies
arXiv:1902.05728 · doi:10.3390/galaxies7010032
Abstract
We present a method for determining directions of magnetic field vectors in a spiral galaxy using two synchrotron polarization maps, an optical image, and a velocity field. The orientation of the transverse magnetic field is determined with a synchrotron polarization map of higher frequency band and the -ambiguity is solved by using sign of the Rotation Measure (RM) after determining geometrical orientation of a disk based on a assumption of trailing spiral arms. The advantage of this method is that direction of magnetic vector for each line of sight through the galaxy can be inexpensively determined with easily available data and with simple assumptions. We applied this method to three nearby spiral galaxies using archival data obtained with the Very Large Array (VLA) to demonstrate how it works. The three galaxies have both clockwise and counter-clockwise magnetic fields, which implies that all three galaxies are not classified in simple Axis-Symmetric type but types of higher modes and that magnetic reversals commonly exist.
arXiv comment9 pages, 5figures
References in corpus (8)
- Magnetic fields and spiral arms in the galaxy M51
- Nobeyama CO Atlas of Nearby Spiral Galaxies: Distribution of Molecular Gas in Barred and Non-barred Spiral Galaxies
- Magnetism in the spiral galaxy NGC 6946: magnetic arms, depolarization rings, dynamo modes and helical fields
- Discovery of a strong spiral magnetic field crossing the inner pseudoring of NGC 4736
- Magnetic field structures of galaxies derived from analysis of Faraday rotation measures, and perspectives for the SKA
- Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy
- Magnetic fields in the absence of spiral density waves - NGC 4414
- The Primordial Origin Model of Magnetic Fields in Spiral Galaxies