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Paper   IPM / Astronomy / 16100
School of Astronomy
  Title:   The Magnetized Disk-Halo Transition Region of M51
  Author(s): 
1.  M. Kierdorf
2.  S. A. Mao
3.  A. Fletcher
4.  R. Beck
5.  M. Haverkorn
6.  A. Basu
7.  F. Tabatabaei
8.  J. Ott
  Status:   Published
  Journal: IAU
  Vol.:  14
  Year:  2020
  Pages:   319-322
  Supported by:            ipm IPM
  Abstract:
An excellent laboratory for studying large scale magnetic fields is the grand de- sign face-on spiral galaxy M51. Due to wavelength-dependent Faraday depolarization, linearly polarized synchrotron emission at different radio frequencies gives a picture of the galaxy at different depths: Observations at L-band (1-2 GHz) probe the halo region while at C- and X- band (4-8 GHz) the linearly polarized emission probe the disk region of M51. We present new observations of M51 using the Karl G. Jansky Very Large Array (VLA) at S-band (2-4 GHz), where previously no polarization observations existed, to shed new light on the transition region between the disk and the halo. We discuss a model of the depolarization of synchrotron radiation in a multilayer magneto-ionic medium and compare the model predictions to the multi-frequency polarization data of M51 between 1-8GHz. The new S-band data are essential to distinguish between different models. Our study shows that the initial model parameters, i.e. the total reg- ular and turbulent magnetic field strengths in the disk and halo of M51, need to be adjusted to successfully fit the models to the data.

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