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ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240

Scoville, Nick and Sheth, Kartik and Walter, Fabian and Manohar, Swarnima and Zschaechner, Laura and Yun, Min and Koda, Jin and Sanders, David B. and Murchikova, Lena and Thompson, Todd and Robertson, Brant and Genzel, R. and Hernquist, Lars and Tacconi, Linda and Brown, Robert and Narayanan, Desika and Hayward, Christopher C. and Barnes, Joshua and Kartaltepe, Jeyhan S. and Davies, Richard and van der Werf, Paul and Fomalont, Edward (2015) ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240. Astrophysical Journal, 800 (1). Art. No. 70. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20150316-140818569

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Abstract

We report ALMA Band 7 (350 GHz) imaging at 0."4-0."6 resolution and Band 9 (696 GHz) at ~0."25 resolution of the luminous IR galaxies Arp 220 and NGC 6240. The long wavelength dust continuum is used to estimate interstellar medium masses for Arp 220 east and west and NGC 6240 of 1.9, 4.2, and 1.6 × 10^9 M_☉ within radii of 69, 65, and 190 pc. The HCN emission was modeled to derive the emissivity distribution as a function of radius and the kinematics of each nuclear disk, yielding dynamical masses consistent with the masses and sizes derived from the dust emission. In Arp 220, the major dust and gas concentrations are at radii less than 50 pc in both counter-rotating nuclear disks. The thickness of the disks in Arp 220 estimated from the velocity dispersion and rotation velocities are 10-20 pc and the mean gas densities are n_H_2 ~ 10^5 cm^(–3) at R <50 pc. We develop an analytic treatment for the molecular excitation (including photon trapping), yielding volume densities for both the HCN and CS emission with n_(H2) ~ 2 × 10^5 cm^(–3). The agreement of the mean density from the total mass and size with that required for excitation suggests that the volume is essentially filled with dense gas, i.e., it is not cloudy or like swiss cheese.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-637X/800/1/70DOIArticle
http://iopscience.iop.org/0004-637X/800/1/70PublisherArticle
http://arxiv.org/abs/1412.5183arXivDiscussion Paper
ORCID:
AuthorORCID
Scoville, Nick0000-0002-0438-3323
Sheth, Kartik0000-0002-5496-4118
Walter, Fabian0000-0003-4793-7880
Zschaechner, Laura0000-0002-9919-8672
Yun, Min0000-0001-7095-7543
Koda, Jin0000-0002-8762-7863
Sanders, David B.0000-0002-1233-9998
Murchikova, Lena0000-0001-8986-5403
Robertson, Brant0000-0002-4271-0364
Genzel, R.0000-0002-2767-9653
Hernquist, Lars0000-0001-6950-1629
Tacconi, Linda0000-0002-1485-9401
Hayward, Christopher C.0000-0003-4073-3236
Kartaltepe, Jeyhan S.0000-0001-9187-3605
van der Werf, Paul0000-0001-5434-5942
Additional Information:© 2015 American Astronomical Society. Received 2014 October 2; accepted 2014 December 15; published 2015 February 10. We thank the referee for a very thorough reading of the manuscript. We thank Zara Scoville for proofreading the manuscript. K.S. is supported by the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA 2011.0.00175.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan); together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.
Group:TAPIR, Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
National Radio Astronomy ObservatoryUNSPECIFIED
Subject Keywords:galaxies: individual (Arp 220, NGC 6240); galaxies: starburst
Issue or Number:1
Record Number:CaltechAUTHORS:20150316-140818569
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150316-140818569
Official Citation:ALMA Imaging of HCN, CS, and Dust in Arp 220 and NGC 6240 Nick Scoville et al. 2015 ApJ 800 70
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55805
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:16 Mar 2015 21:33
Last Modified:17 Jul 2019 22:16

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