| ID:
720109.0,
MPI für Astronomie / Publikationen_mpia |
| Properties of the magneto-ionic medium in the halo of M51 revealed by wide-band polarimetry |
| Authors: | Mao, S. A.; Zweibel, E.; Fletcher, A.; Ott, J.; Tabatabaei, F. |
| Date of Publication (YYYY-MM-DD): | 2015 |
| Title of Journal: | The Astrophysical Journal |
| Volume: | 800 |
| Issue / Number: | 2 |
| Start Page: | id. 92 (19 pp) |
| Audience: | Not Specified |
| Abstract / Description: | We present a study of the magneto-ionic medium in the Whirlpool galaxy (M51) using new wide-band multi-configuration polarization data at L band (1-2 GHz) obtained at the Karl G. Jansky Very Large Array. By fitting the observed diffuse complex polarization Q+iU as a function of wavelength directly to various depolarization models, we find that polarized emission from M51 at 1-2 GHz originates from the top of the synchrotron disk and then experiences Faraday rotation in the near-side thermal halo of the galaxy. Thus, the scale height of the thermal gas must exceed that of the synchrotron emitting gas at L band. The observed Faraday depth distribution at L band is consistent with a halo field that is comprised of a plane-parallel bisymmetric component and a vertical component that produces a Faraday rotation of ~-9 rad m-2. The derived rotation measure (RM) structure functions indicate a characteristic scale of RM fluctuations of less than 560 pc in the disk and approximately 1 kpc in the halo. The outer scale of turbulence of 1 kpc found in the halo of M51 is consistent with superbubbles and the Parker instability being the main energy injection mechanisms in galactic halos. |
| Free Keywords: | Galaxy: halo; ISM: magnetic fields; polarization |
| External Publication Status: | published |
| Document Type: | Article |
| Communicated by: | N. N. |
| Affiliations: | MPI für Astronomie |
| Identifiers: | ISSN:0004-637X
URL:http://cdsads.u-strasbg.fr/abs/2015ApJ...800...92M
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