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For refcode 1992MNRAS.256p..53T:
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Copyright by Royal Astronomical Society. 1992MNRAS.256p..53T The optical polarizations of high- and intermediate-redshift radio galaxies C. N. Tadhunter, S. M. Scarrott, P. Draper and C. Rolph Department of Physics, University of Sheffield, Sheffield 53 7RH Department of Physics, University of Durham, South Road, Durham DH1 3LE Accepted 1992 March 21. Received 1992 March 21; in original form 1992 January 21 SUMMARY Optical polarization measurements are presented for 12 high- and intermediate-redshift radio galaxies (0.2 < z < 0.85). The data confirm that large optical polarization is relatively common at high redshifts: five out of seven of the z > 0.5 objects with good polarization measurements have their integrated light polarized at the 5-20 percent level. This result, and the fact that the polarization is frequently oriented perpendicular to the radio axis, suggests that a large fraction of the UV continuum has been scattered out of radiation beams from the AGN by dust or electrons in the high-redshift host galaxies. In contrast, we find that none of the intermediate-redshift (0.2 < z < 0.5) objects shows polarization at the > 5 per cent level. It is likely that the implied redshift dependence is largely a consequence of the varying dilution of the polarization by the light from the stars in the haloes of the galaxies - the dilution is least for the high-redshift objects because they are observed in the rest-frame UV- but it is also possible that the scattering ISM is more effective and/or the radiation beams are stronger at high redshifts. Key words: polarization - galaxies: active - radio continuum: galaxies.
Retrieve 16 NED objects in this reference.
Please click here for ADS abstract

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