Abstract
We take advantage of the wealth of rotation measures data contained in the NRAO VLA Sky Survey catalog to derive new, statistically robust, upper limits on the strength of extragalactic magnetic fields. We simulate the extragalactic magnetic field contribution to the rotation measures for a given field strength and correlation length, by assuming that the electron density follows the distribution of Lyman- clouds. Based on the observation that rotation measures from distant radio sources do not exhibit any trend with redshift, while the extragalactic contribution instead grows with distance, we constrain fields with Jeans’ length coherence length to be below 1.7 nG at the level, and fields coherent across the entire observable Universe below 0.65 nG. These limits do not depend on the particular origin of these cosmological fields.
- Received 7 May 2015
DOI:https://doi.org/10.1103/PhysRevLett.116.191302
© 2016 American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Cosmic Magnetism Revisited
Published 12 May 2016
An analysis of the polarized emission from some 3000 distant radio sources places a stringent upper limit on the strength of the cosmological magnetic field.
See more in Physics