Extragalactic Magnetism with SOFIA (Legacy Program). I. The Magnetic Field in the Multiphase Interstellar Medium of M51 - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2021

Extragalactic Magnetism with SOFIA (Legacy Program). I. The Magnetic Field in the Multiphase Interstellar Medium of M51

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1
Alejandro S. Borlaff
  • Function : Author
Enrique Lopez-Rodriguez
  • Function : Author
Rainer Beck
  • Function : Author
Rodion Stepanov
  • Function : Author
Eva Ntormousi
  • Function : Author
Konstantinos Tassis
  • Function : Author
Pamela M. Marcum
  • Function : Author
Lucas Grosset
  • Function : Author
John E. Beckman
  • Function : Author
Leslie Proudfit
  • Function : Author
Susan E. Clark
  • Function : Author
Tanio Díaz-Santos
Sui Ann Mao
  • Function : Author
William T. Reach
  • Function : Author
Julia Roman-Duval
Kandaswamy Subramanian
  • Function : Author
Le Ngoc Tram
  • Function : Author
Ellen G. Zweibel
  • Function : Author
Daniel Dale

Abstract

The recent availability of high-resolution far-infrared (FIR) polarization observations of galaxies using HAWC+/SOFIA has facilitated studies of extragalactic magnetic fields in the cold and dense molecular disks. We investigate whether any significant structural differences are detectable in the kiloparsec-scale magnetic field of the grand design face-on spiral galaxy M51 when traced within the diffuse (radio) and the dense and cold (FIR) interstellar medium (ISM). Our analysis reveals a complex scenario where radio and FIR polarization observations do not necessarily trace the same magnetic field structure. We find that the magnetic field in the arms is wrapped tighter at 154 μm than at 3 and 6 cm; statistically significant lower values for the magnetic pitch angle are measured at FIR in the outskirts (R ≥ 7 kpc) of the galaxy. This difference is not detected in the interarm region. We find strong correlations of the polarization fraction and total intensity at FIR and radio with the gas column density and 12CO(1-0) velocity dispersion. We conclude that the arms show a relative increase of small-scale turbulent B-fields at regions with increasing column density and dispersion velocities of the molecular gas. No correlations are found with H I neutral gas. The star formation rate shows a clear correlation with the radio polarized intensity, which is not found in FIR, pointing to a small-scale dynamo-driven B-field amplification scenario. This work shows that multiwavelength polarization observations are key to disentangling the interlocked relation between star formation, magnetic fields, and gas kinematics in the multiphase ISM. * The SOFIA Legacy Group for Magnetic Fields in Galaxies software repository is available at https://github.com/galmagfields/hawc via the official project website, http://galmagfields.com/, and Zenodo/GitHub, https://doi.org/10.5281/zenodo.5116134.

Dates and versions

insu-03672382 , version 1 (19-05-2022)

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Cite

Alejandro S. Borlaff, Enrique Lopez-Rodriguez, Rainer Beck, Rodion Stepanov, Eva Ntormousi, et al.. Extragalactic Magnetism with SOFIA (Legacy Program). I. The Magnetic Field in the Multiphase Interstellar Medium of M51. The Astrophysical Journal, 2021, 921, ⟨10.3847/1538-4357/ac16d7⟩. ⟨insu-03672382⟩
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