The Spatial energy spectrum of magnetic fields in our galaxy

Apr, 2004
7 pages
Published in:
  • Astrophys.J. 610 (2004) 820-826
e-Print:

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Abstract: (arXiv)
Interstellar magnetic fields exist over a broad range of spatial scales, extending from the large Galactic scales (10\sim 10 kpc) down to the very small dissipative scales (1\ll 1 pc). In this paper, we use a set of 490 pulsars distributed over roughly one third of the Galactic disk out to a radius R10R \simeq 10 kpc (assuming R=8.5R_\odot = 8.5 kpc) and combine their observed rotation and dispersion measures with their estimated distances to derive the spatial energy spectrum of the Galactic interstellar magnetic field over the scale range 0.5150.5 - 15 kpc. We obtain a nearly flat spectrum, with a 1D power-law index α=0.37±0.10\alpha=-0.37\pm0.10 for EB(k)=CkαE_{\rm B}(k)=C k^{\alpha} and an rms field strength of approximately 6μ6 \muG over the relevant scales. Our study complements the derivation of the magnetic energy spectrum over the scale range 0.031000.03 - 100 pc by \citet{ms96b}, showing that the magnetic spectrum becomes flatter at larger scales. This observational result is discussed in the framework of current theoretical and numerical models.
Note:
  • 7 pages, 6 figures, ApJ accepted Journal-ref: Astrophys.J. 610 (2004) 820-826 DOI: 10.1086/421760
  • ISM: magnetic fields
  • pulsars: general
  • turbulence