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Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068

Lopez-Rodriguez, E. and Packham, C. and Roche, P. F. and Alonso-Herrero, A. and Díaz-Santos, T. and Nikutta, R. and González-Martín, O. and Álvarez, C. A. and Esquej, P. and Rodríguez-Espinosa, J. M. and Perlman, E. and Ramos Almeida, C. and Telesco, C. M. (2016) Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068. Monthly Notices of the Royal Astronomical Society, 458 (4). pp. 3851-3866. ISSN 0035-8711.

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We present subarcsecond 7.5–13 μm imaging- and spectro-polarimetric observations of NGC 1068 using CanariCam on the 10.4-m Gran Telescopio CANARIAS. At all wavelengths, we find: (1) A 90 × 60 pc extended polarized feature in the northern ionization cone, with a uniform ∼44∘ polarization angle. Its polarization arises from dust and gas emission in the ionization cone, heated by the active nucleus and jet, and further extinguished by aligned dust grains in the host galaxy. The polarization spectrum of the jet–molecular cloud interaction at ∼24 pc from the core is highly polarized, and does not show a silicate feature, suggesting that the dust grains are different from those in the interstellar medium. (2) A southern polarized feature at ∼9.6 pc from the core. Its polarization arises from a dust emission component extinguished by a large concentration of dust in the galaxy disc. We cannot distinguish between dust emission from magnetically aligned dust grains directly heated by the jet close to the core, and aligned dust grains in the dusty obscuring material surrounding the central engine. Silicate-like grains reproduce the polarized dust emission in this feature, suggesting different dust compositions in both ionization cones. (3) An upper limit of polarization degree of 0.3 per cent in the core. Based on our polarization model, the expected polarization of the obscuring dusty material is ≲0.1 per cent in the 8–13 μm wavelength range. This low polarization may be arising from the passage of radiation through aligned dust grains in the shielded edges of the clumps.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Lopez-Rodriguez, E.0000-0001-5357-6538
Packham, C.0000-0001-7827-5758
Alonso-Herrero, A.0000-0001-6794-2519
Díaz-Santos, T.0000-0003-0699-6083
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 March 3. Received 2016 March 1. In original form 2015 August 4. First published online March 7, 2016. It is a pleasure to acknowledge discussion with R. Mason. We would like to thank the anonymous referee for their useful comments, which improved the paper significantly. Based on observations made with the Gran Telescopio CANARIAS (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. ELR and CP acknowledge support from the University of Texas at San Antonio. CP acknowledges support from NSF-0904421 grant. AA-H acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the 2011 Severo Ochoa Program MINECO SEV-2011- 0187. AA-H acknowledges financial support from the Spanish Ministry of Economy and Competitiveness through grant AYA2012-31447, which is partly funded by the FEDER program, PE from grant AYA2012-31277, and LC from grant AYA2012-32295. RN acknowledges support by FONDECYT grant no. 3140436. CRA is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-327934). EP acknowledges support from NSF grant AST-0904896.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
University of Texas-San AntonioUNSPECIFIED
Ministerio de Economía y Competitividad (MINECO)MINECO SEV-2011-0187
Ministerio de Economía y Competitividad (MINECO)AYA2012-31447
Ministerio de Economía y Competitividad (MINECO)AYA2012-31277
Ministerio de Economía y Competitividad (MINECO)AYA2012-32295
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3140436
Marie Curie FellowshipPIEF-GA-2012-327934
Subject Keywords:methods: observational techniques: high angular resolution techniques: polarimetric galaxies: individual: NGC 1068 galaxies: Seyfert infrared: galaxies
Issue or Number:4
Record Number:CaltechAUTHORS:20160610-113139356
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Official Citation:E. Lopez-Rodriguez, C. Packham, P. F. Roche, A. Alonso-Herrero, T. Díaz-Santos, R. Nikutta, O. González-Martín, C. A. Álvarez, P. Esquej, J. M. Rodríguez Espinosa, E. Perlman, C. Ramos Almeida, and C. M. Telesco Mid-infrared imaging- and spectro-polarimetric subarcsecond observations of NGC 1068 MNRAS (June 01, 2016) Vol. 458 3851-3866 doi:10.1093/mnras/stw541 first published online March 7, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67835
Deposited By: Ruth Sustaita
Deposited On:10 Jun 2016 19:00
Last Modified:09 Mar 2020 13:19

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