Ramirez, E.A., Tadhunter, C.N., Axon, D. et al. (5 more authors) (2014) Near-infrared Hubble Space Telescope polarimetry of a complete sample of narrow-line radio galaxies. Monthly Notices of the Royal Astronomical Society, 444 (1). pp. 466-475. ISSN 0035-8711
Abstract
We present an analysis of 2.05 μm Hubble Space Telescope polarimetric data for a sample of 13 nearby Fanaroff–Riley type II (FRII) 3CR radio sources (0.03 < z < 0.11) that are classified as narrow-line radio galaxies (NLRG) at optical wavelengths. We find that the compact cores of the NLRG in our sample are intrinsically highly polarized in the near-infrared (near-IR) (6 < P2.05 μm < 60 per cent), with the electric vector (E-vector) perpendicular to the radio axis in 54 per cent of the sources. The levels of extinction required to produce near-IR polarization by the dichroic extinction mechanism are consistent with the measured values recently reported in Ramírez et al., provided that this mechanism has its maximum efficiency. This consistency suggests that the nuclear polarization could be due to dichroic extinction. In this case, toroidal magnetic fields that are highly coherent would be required in the circumnuclear tori to align the elongated dust grains responsible for the dichroic extinction. However, it is not entirely possible to rule out other polarization mechanisms (e.g. scattering, synchrotron emission) with our observations at only one near-IR wavelength. Therefore, further polarimetry observations at mid-IR and radio wavelengths will be required to test whether all the near-IR polarization is due to dichroic extinction.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | techniques: polarimetric; galaxies: active; infrared: galaxies |
Dates: |
|
Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Oct 2017 10:43 |
Last Modified: | 27 Oct 2017 10:46 |
Published Version: | https://doi.org/10.1093/mnras/stu1390 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/stu1390 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:122741 |