Variations in the small-scale galactic magnetic field and short time-scale intensity variations of extragalactic radio sources
Structure functions of the Faraday rotation measures (RMs) of extragalactic radio sources are used to investigate variations in the interstellar magnetic field on length scales of approx.0.01 to 100 pc. Model structure functions derived assuming a power-law power spectrum of irregularities in n/sub e/B, are compared with those observed. The results indicate an outer angular scale for RM variations of approximately less than or equal to 5/sup 0/ and evidence for RM variations on scales as small as 1'. Differences in the variance of n/sub e/B fluctuations for various lines of sight through the Galaxy are found. Comparison of pulsar scintillations in right- and left-circular polarizations yield an upper limit to the variations in n/sub e/ on a length scale of approx.10/sup 11/ cm. RMs were determined through high-velocity molecular flows in galactic star-formation regions, with the goal of constraining magnetic fields in and near the flows. RMs of 7 extragalactic sources with a approx.20 arcmin wide area seen through Cep A, fall in two groups separated by approx.150 rad m/sup -2/ - large given our knowledge of RM variations on small angular scales and possibly a result of the anisotropy of the high-velocity material.
- Research Organization:
- Cornell Univ., Ithaca, NY (USA)
- OSTI ID:
- 5472116
- Country of Publication:
- United States
- Language:
- English
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