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Title: THE EXTENT OF MAGNETIC FIELDS AROUND GALAXIES OUT TO z {approx} 1

Radio quasar sightlines with strong Mg II absorption lines display statistically enhanced Faraday rotation measures (RMs), indicating the presence of additional magneto-active plasma with respect to sightlines free of such absorption. In this Letter, we use multi-color optical imaging to identify the galaxies likely hosting the magneto-active plasma, and to constrain the location of the latter with respect to the putative parent halo. We find that all of the sightlines with high |RM| pass within 50 kpc of a galaxy and that the |RM| distribution for low impact parameters, D < 50 kpc, is significantly different than for larger impact parameters. In addition, we find a decrease in the ratio of the polarization at 21 cm and 1.5 cm, p{sub 21}/p{sub 1.5}, toward lower D. These two effects are most likely related, strengthen the association of excess |RM| with intervening galaxies, and suggest that intervening galaxies operate as inhomogeneous Faraday screens. These results are difficult to reconcile with only a disk model for the magnetic field, but are consistent with highly magnetized winds associated with Mg II systems. We infer strong magnetic fields of a few tens of {mu}G, consistent with the values required by the lack of evolution ofmore » the FIR-radio correlation at high redshifts. Finally, these findings lend support to the idea that the small-scale helicity bottleneck of {alpha}-{Omega} galactic dynamos can be significantly alleviated via galactic winds.« less
Authors:
; ;  [1]
  1. Physics Department, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)
Publication Date:
OSTI Identifier:
22140321
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 772; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; COLOR; CORRELATIONS; DISTRIBUTION; EVOLUTION; FAR INFRARED RADIATION; FARADAY EFFECT; GALAXIES; HELICITY; IMPACT PARAMETER; MAGNETIC FIELDS; PLASMA; POLARIZATION; QUASARS; RED SHIFT; STELLAR WINDS