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Constraining the ISM Properties of the Cloverleaf Quasar Host Galaxy with Herschel Spectroscopy

Uzgil, Bade D. and Bradford, C. Matt and Hailey-Dunsheath, Steve and Maloney, Philip R. and Aguirre, James E. (2016) Constraining the ISM Properties of the Cloverleaf Quasar Host Galaxy with Herschel Spectroscopy. Astrophysical Journal, 832 (2). Art. No. 209. ISSN 0004-637X.

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We present Herschel observations of the far-infrared (FIR) fine-structure (FS) lines [C II]158 μm, [O I]63 μm, [O III]52 μm, and [Si II]35 μm in the z = 2.56 Cloverleaf quasar, and combine them with published data in an analysis of the dense interstellar medium (ISM) in this system. Observed [C II]158 μm, [O I]63 μm, and FIR continuum flux ratios are reproduced with photodissociation region (PDR) models characterized by moderate far-ultraviolet (FUV) radiation fields with G_0 = 0.3–1 × 10^3 and atomic gas densities n_H = 3–5 × 10^3 cm^(−3), depending on contributions to [C II]158 μm from ionized gas. We assess the contribution to the [C II]158 μm flux from an active galactic nucleus (AGN) narrow line region (NLR) using ground-based measurements of the [N II]122 μm transition, finding that the NLR can contribute at most 20%–30% of the observed [C II]158 μm flux. The PDR density and far-UV radiation fields inferred from the atomic lines are not consistent with the CO emission, indicating that the molecular gas excitation is not solely provided via UV heating from local star formation (SF), but requires an additional heating source. X-ray heating from the AGN is explored, and we find that X-ray-dominated region (XDR) models, in combination with PDR models, can match the CO cooling without overproducing the observed FS line emission. While this XDR/PDR solution is favored given the evidence for both X-rays and SF in the Cloverleaf, we also investigate alternatives for the warm molecular gas, finding that either mechanical heating via low-velocity shocks or an enhanced cosmic-ray ionization rate may also contribute. Finally, we include upper limits on two other measurements attempted in the Herschel program: [C II]158 μm in FSC 10214 and [O I]63 μm in APM 08279+5255.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Uzgil, Bade D.0000-0001-8526-3464
Bradford, C. Matt0000-0001-5261-7094
Hailey-Dunsheath, Steve0000-0002-8504-7988
Aguirre, James E.0000-0002-4810-666X
Additional Information:© 2016 The American Astronomical Society. Received 2016 May 17; revised 2016 September 22; accepted 2016 September 27; published 2016 December 1. The authors would like to thank Nanyao Lu for help assessing the noise level in the Herschel-FTS spectra of the Cloverleaf. We thank Carl Ferkinhoff for discussions related to the [N ii]122 μm data from ALMA. We thank Lee Armus and Tanio Díaz-Santos for helpful discussions and comments on the manuscript, and for providing us with results from an analysis of [C ii]158 μm and PAH emission in GOALS galaxies. We would also like to thank Aaron Evans, Brent Groves, J.D. Smith, and Fabian Walter for helpful discussions related to this work. B.D.U. acknowledges support from the NASA Graduate Student Research Program fellowship and NSF AST 1455151. These investigations made use of Herschel open-time award funds from NASA through a JPL/Caltech award no. 1489920 to C.M.B.
Funding AgencyGrant Number
NASA Graduate Student Research FellowshipUNSPECIFIED
Subject Keywords:galaxies: active – galaxies: individual (H11413+117) – galaxies: ISM – infrared: galaxies
Issue or Number:2
Record Number:CaltechAUTHORS:20161205-153231425
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Official Citation:Bade D. Uzgil et al 2016 ApJ 832 209
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72574
Deposited By: Tony Diaz
Deposited On:06 Dec 2016 02:06
Last Modified:23 Oct 2020 18:26

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