A deep look at the nuclear region of UGC 5101 through high angular resolution mid-IR data with GTC/CanariCam

Creators: Martínez-Paredes, M.; Alonso-Herrero, A.; Aretxaga, I.; Ramos Almeida, C.; Hernán-Caballero, A.; González-Martín, O.; Pereira-Santaella, M.; Packham, C.; Asensio Ramos, A.; Díaz-Santos, T.; Elitzur, M.; Esquej, P.; García-Bernete, I.; Imanishi, M.; Levenson, N. A.; Rodríguez Espinosa, J. M.

Abstract

We present an analysis of the nuclear infrared (IR, 1.6–18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3–0.5 arcsec) imaging using the Si-2 filter (λ_C = 8.7 μm) and 7.5–13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose the Spitzer/IRS and CC spectra using a power-law component, which represents the emission due to dust heated by the AGN, and a starburst component, both affected by foreground extinction. We model the resulting unresolved near- and mid-IR, and the starburst subtracted CC spectrum with the CLUMPY torus models of Nenkova et al. The derived geometrical properties of the torus, including the large covering factor and the high foreground extinction needed to reproduce the deep 9.7 μm silicate feature, are consistent with the lack of strong AGN signatures in the optical. We derive an AGN bolometric luminosity L_(bo)l ∼ 1.9 × 10^(45) erg s^(−1) that is in good agreement with other estimates in the literature.

Additional Information

© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 September 14. Received 2015 September 4; in original form 2015 February 3. First published online October 20, 2015. We thank the referee for a thorough report that has improved the paper significantly. This work has been partly supported by Mexican CONACyT under research grant CB-2011-01-167291. MM-P acknowledges support by the CONACyT PhD fellowship programme. AA-H and AH-C acknowledge financial support from the Spanish Plan Nacional de Astronomía y Astrofísica under grant AYA2012-31447, which is partly funded by the FEDER programme, and the Universidad de Cantabria through the Augusto G. Linares programme. CRA is supported by a Marie Curie Intra European Fellowship within the 7th European Community Framework Programme (PIEF-GA-2012-327934). IG-B acknowledges financial support from the Instituto de Astrofísica de Canarias through Fundación La Caixa and from the Spanish Ministry of Science and Innovation (MICINN) through project PN AYA2013-47742-c4-2-P (Estallidos). This work is based on observations made with the GTC, installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma. It is also based partly on observations obtained with the Spitzer Space Observatory, which is operated by JPL, Caltech, under NASA contract 1407. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by JPL, Caltech, under contract with the National Aeronautics and Space Administration. The CASSIS is a product of the Infrared Science Center at Cornell University, supported by NASA and JPL. Based on observations made with the NASA/ESA HST, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

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