SIMBAD references

2013ApJ...772L..28B - Astrophys. J., 772, L28 (2013/August-1)

The extent of magnetic fields around galaxies out to z ∼ 1.


Abstract (from CDS):

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, p21/p1.5, 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 µG, consistent with the values required by the lack of evolution of the FIR-radio correlation at high redshifts. Finally, these findings lend support to the idea that the small-scale helicity bottleneck of α-Ω galactic dynamos can be significantly alleviated via galactic winds.

Abstract Copyright:

Journal keyword(s): galaxies: evolution - galaxies: high-redshift - galaxies: magnetic fields - quasars: absorption lines

Simbad objects: 32

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