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For refcode 1990MNRAS.244..577B:
Retrieve 74 NED objects in this reference.
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NED Abstract

Copyright by Royal Astronomical Society. 1990MNRAS.244..577B An optical and near-infrared polarization survey of Seyfert and broad-line radio galaxies - I. Statistical properties C. Brindle and J. H. Hough Division of Physical Sciences, Hatfield Polytechnic, Hatfield. Herts AL10 9AB J. A. Bailey Anglo-Australian Observatory, P.O. Box 296, Epping, NSW 2121, Australia D. J. Axon University of Manchester, Nuffield Radio Astronomy Laboratories, Jodrell Bank, Macclesfeld, Cheshire SK11 9DL M. J. Ward Institute of Astronomy, Madingley Road, Cambridge CB3 0HA W. B. Sparks Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, USA I. S. McLean Joint Astronomy Centre, 665 Komohana Street, Hilo, Hawaii 96720, USA Accepted 1989 December 7. Received 1989 November 27; in original form 1988 October 19 SUMMARY We present new broad-band optical and near-infrared (0.44-2.2 micron) flux density and polarization measurements of a sample of 71 Seyfert galaxies and three broad-line radio galaxies. We confirm the results of earlier studies which show that the polarization of Seyferts is generally low (P < 1 per cent) in the V-band and at longer wavelengths, but in the B-band somewhat higher polarizations are commonly found. After correction has been made for the effects of stellar dilution, we find that Seyfert 2 nuclei are probably more highly polarized than Seyfert 1's. The small sample of Seyfert 2's selected using the 'warm' IRAS colour criterion tend to be more highly polarized than those selected by optical techniques. Comparison of repeat polarization observations and those from other studies show no evidence of significant variability. There is a tendency for the polarization to be parallel to the galaxy optical or dust-lane axis, and we confirm previous findings that the polarization of Seyfert 2's tends to be perpendicular to the radio axis. For the objects with a prominent broad-line region visible in their optical line profiles, rank correlation tests show that the degree of 'optical' polarization is correlated with the following: redshift, V-band magnitude, Balmer decrement, near-infrared colours and the slope of the optical to near-infrared continuum. It anti-correlates with axial ratio and the slope of the 25-60 micron continuum. We also find a significant correlation between B-band polarization and B-V, and a tentative anti- correlation between H-band polarization and L [O III]. Transmission of the continuum radiation through aligned dust grains and scattering are likely to be the most important polarization mechanisms in the majority of these objects. In contrast, for the objects which lack a strong broad-line region (Seyfert 1.8's, 1.9's and 2's), rank correlation tests show that the degree of 'optical' polarization is correlated with the following: V-band magnitude, L (25 micron) and near-infrared colours. There is a tentative correlation with L [O III]. The high intrinsic polarizations observed in some of these objects, the lack of a correlation with reddening sensitive indicators, together with the strong tendency for the polarization to be perpendicular to the radio axis, suggest that the dominant polarization mechanism is scattering in the narrow-line region. For both groups of galaxies, a non-thermal component may contribute significantly to the polarization in the near-infrared.
Retrieve 74 NED objects in this reference.
Please click here for ADS abstract

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