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NICMOS Polarimetry of ''Polar-scattered'' Seyfert 1 Galaxies

Batcheldor, D.; Robinson, A.; Axon, D.J.; Young, S.; Quinn, S.; Smith, J.E.; Hough, J.; Alexander, D.M.

NICMOS Polarimetry of ''Polar-scattered'' Seyfert 1 Galaxies Thumbnail


D. Batcheldor

A. Robinson

D.J. Axon

S. Young

S. Quinn

J.E. Smith

J. Hough


The nuclei of Seyfert 1 galaxies exhibit a range of optical polarization characteristics that can be understood in terms of two scattering regions producing orthogonal polarizations: an extended polar scattering region (PSR) and a compact equatorial scattering region (ESR), located within the circum-nuclear torus. Here we present NICMOS 2.0 μm imaging polarimetry of six "polar-scattered" Seyfert 1 (S1) galaxies, in which the PSR dominates the optical polarization. The unresolved nucleus (<0farcs58) is significantly polarized in only three objects, but five of the six exhibit polarization in a 0farcs58-1farcs5 circum-nuclear annulus. In Fairall 51 and ESO 323-G077, the polarization position angle at 2 μm (θ2 μm) is consistent with the average for the optical spectrum(θ v ), implying that the nuclear polarization is dominated by polar scattering at both wavelengths. The same is probably true for NGC 3227. In both NGC 4593 and Mrk 766, there is a large difference between θ2 μm and θ v off-nucleus, where polar scattering is expected to dominate. This may be due to contamination by interstellar polarization in NGC 4593, but there is no clear explanation in the case of the strongly polarized Mrk 766. Lastly, in Mrk 1239, a large change (≈60°) in θ2 μm between the nucleus and the annulus indicates that the unresolved nucleus and its immediate surroundings have different polarization states at 2 μm, which we attribute to the ESR and PSR, respectively. A further implication is that the source of the scattered 2 μm emission in the unresolved nucleus is the accretion disk, rather than torus hot dust emission. Based on observations made with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program 10160.


Batcheldor, D., Robinson, A., Axon, D., Young, S., Quinn, S., Smith, J., …Alexander, D. (2011). NICMOS Polarimetry of ''Polar-scattered'' Seyfert 1 Galaxies. Astrophysical Journal, 738(1), Article 90.

Journal Article Type Article
Publication Date Sep 1, 2011
Deposit Date Apr 8, 2013
Publicly Available Date Jan 3, 2014
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 738
Issue 1
Article Number 90
Keywords Galaxies: nuclei, Galaxies: Seyfert, Infrared: galaxies, Polarization, Scattering, Techniques: polarimetric.
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Published Journal Article (501 Kb)

Copyright Statement
© 2011. The American Astronomical Society. All rights reserved. Printed in the U.S.A.

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