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Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution

Treister, Ezequiel and Messias, Hugo and Privon, George C. and Nagar, Neil and Medling, Anne M. and U, Vivian and Bauer, Franz E. and Cicone, Claudia and Barcos Muñoz, Loreto and Evans, Aaron S. and Müller-Sánchez, Francisco and Comerford, Julia M. and Armus, Lee and Chang, Chin-Shin and Koss, Michael and Venturi, Giacomo and Schawinski, Kevin and Casey, Caitlin and Urry, C. Megan and Sanders, David B. and Scoville, Nicholas and Sheth, Kartik (2020) Molecular Gas in the NGC 6240 Merging Galaxy System at the Highest Spatial Resolution. Astrophysical Journal, 890 (2). Art. No. 149. ISSN 1538-4357. doi:10.3847/1538-4357/ab6b28.

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We present the highest-resolution—15 pc (0.”03)—ALMA ¹²CO(2–1) line emission and 1.3 mm continuum maps, tracers of the molecular gas and dust, respectively, in the nearby merging galaxy system NGC 6240, which hosts two supermassive black holes growing simultaneously. These observations provide an excellent spatial match to existing Hubble Space Telescope (HST) optical and near-infrared observations of this system. A significant molecular gas mass, ~9 × 10⁹ M⊙, is located between the two nuclei, forming a clumpy stream kinematically dominated by turbulence, rather than a smooth rotating disk, as previously assumed from lower-resolution data. Evidence for rotation is seen in the gas surrounding the southern nucleus but not in the northern one. Dynamical shells can be seen, likely associated with nuclear supernova remnants. We further detect the presence of significant high-velocity outflows, some of them reaching velocities >500 km s⁻¹, affecting a significant fraction, ~11%, of the molecular gas in the nuclear region. Inside the spheres of influence of the northern and southern supermassive black holes, we find molecular masses of 7.4 × 10⁸ and 3.3 × 10⁹ M⊙, respectively. We are thus directly imaging the reservoir of gas that can accrete onto each supermassive black hole. These new ALMA maps highlight the critical need for high-resolution observations of molecular gas in order to understand the feeding of supermassive black holes and its connection to galaxy evolution in the context of a major galaxy merger.

Item Type:Article
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URLURL TypeDescription Paper
Treister, Ezequiel0000-0001-7568-6412
Messias, Hugo0000-0002-2985-7994
Privon, George C.0000-0003-3474-1125
Nagar, Neil0000-0001-6920-662X
Medling, Anne M.0000-0001-7421-2944
U, Vivian0000-0002-1912-0024
Bauer, Franz E.0000-0002-8686-8737
Cicone, Claudia0000-0003-0522-6941
Barcos Muñoz, Loreto0000-0003-0057-8892
Evans, Aaron S.0000-0003-2638-1334
Müller-Sánchez, Francisco0000-0002-2713-0628
Comerford, Julia M.0000-0001-8627-4907
Armus, Lee0000-0003-3498-2973
Chang, Chin-Shin0000-0001-9910-3234
Koss, Michael0000-0002-7998-9581
Venturi, Giacomo0000-0001-8349-3055
Schawinski, Kevin0000-0001-5464-0888
Casey, Caitlin0000-0002-0930-6466
Urry, C. Megan0000-0002-0745-9792
Sanders, David B.0000-0002-1233-9998
Scoville, Nicholas0000-0002-0438-3323
Sheth, Kartik0000-0002-5496-4118
Additional Information:© 2020 The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2019 September 4; revised 2019 December 26; accepted 2020 January 2; published 2020 February 24. We thank the anonymous referee for a very constructive review of this article. We acknowledge support from FONDECYT Regular 1160999 (E.T.), 1190818 (E.T., F.E.B.), CONICYT PIA ACT172033 (E.T., N.N.), Basal-CATA PFB-06/2007 (E.T., F.E.B., N.N.), and AFB170002 (E.T., F.E.B., G.V., N.N.) grants and Chile's Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to the Millennium Institute of Astrophysics, MAS (F.E.B.). G.C.P. acknowledges support from the University of Florida. C.C. acknowledges funding from the European Union Horizon 2020 research and innovation program under Marie Skłodowska Curie grant agreement No. 664931. This work was performed in part at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.00370.S and #2015.1.00003.S. ALMA is a partnership of the ESO (representing its member states), NSF (USA), and NINS (Japan), together with the NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, AUI/NRAO, and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Facility: ALMA. -
Group:Astronomy Department
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1160999
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1190818
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)PIA ACT172033
Iniciativa Científica Milenio del Ministerio de Economía, Fomento y TurismoIC120009
University of FloridaUNSPECIFIED
Marie Curie Fellowship664931
Subject Keywords:Galaxy mergers; Galaxy interactions; Active galaxies; AGN host galaxies; Active galactic nuclei; Molecular gas
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Galaxy mergers (608); Galaxy interactions (600); Active galaxies (17); AGN host galaxies (2017); Active galactic nuclei (16); Molecular gas (1073)
Record Number:CaltechAUTHORS:20200224-131202531
Persistent URL:
Official Citation:Ezequiel Treister et al 2020 ApJ 890 149
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101500
Deposited By: Tony Diaz
Deposited On:24 Feb 2020 21:30
Last Modified:16 Nov 2021 18:03

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