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Strong Far-Infrared Cooling Lines, Peculiar CO Kinematics, and Possible Star-Formation Suppression in Hickson Compact Group 57

Alatalo, K. and Appleton, P. N. and Lisenfeld, U. and Bitsakis, T. and Guillard, P. and Charmandaris, V. and Cluver, M. and Dopita, M. A. and Freeland, E. and Jarrett, T. and Kewley, L. J. and Ogle, P. M. and Rasmussen, J. and Rich, J. A. and Verdes-Montenegro, L. and Xu, C. K. and Yun, M. (2014) Strong Far-Infrared Cooling Lines, Peculiar CO Kinematics, and Possible Star-Formation Suppression in Hickson Compact Group 57. Astrophysical Journal, 795 (2). Art. No. 159. ISSN 0004-637X.

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We present [C II] and [O I] observations from Herschel and CO(1–0) maps from the Combined Array for Research in Millimeter Astronomy (CARMA) of the Hickson Compact Group HCG 57, focusing on the galaxies HCG 57a and HCG 57d. HCG 57a has been previously shown to contain enhanced quantities of warm molecular hydrogen consistent with shock and/or turbulent heating. Our observations show that HCG 57d has strong [C II] emission compared to LFIR and weak CO(1–0), while in HCG 57a, both the [C II] and CO(1–0) are strong. HCG 57a lies at the upper end of the normal distribution of [C II]/CO and [C II]/FIR ratios, and its far-IR cooling supports a low density warm diffuse gas that falls close to the boundary of acceptable PDR models. However, the power radiated in the [C II] and warm H_2 emission have similar magnitudes, as seen in other shock-dominated systems and predicted by recent models. We suggest that shock-heating of the [C II] is a viable alternative to photoelectric heating in violently disturbed diffuse gas. The existence of shocks is also consistent with peculiar CO kinematics in the galaxy, indicating highly non-circular motions are present. These kinematically disturbed CO regions also show evidence of suppressed star formation, falling a factor of 10–30 below normal galaxies on the Kennicutt-Schmidt relation. We suggest that the peculiar properties of both galaxies are consistent with a highly dissipative off-center collisional encounter between HCG 57d and 57a, creating ring-like morphologies in both systems. Highly dissipative gas-on-gas collisions may be more common in dense groups because of the likelihood of repeated multiple encounters. The possibility of shock induced SF suppression may explain why a subset of these HCG galaxies have been found previously to fall in the mid-infrared green valley.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Alatalo, K.0000-0002-4261-2326
Appleton, P. N.0000-0002-7607-8766
Lisenfeld, U.0000-0002-9471-5423
Bitsakis, T.0000-0001-5787-8242
Guillard, P.0000-0002-2421-1350
Charmandaris, V.0000-0002-2688-1956
Cluver, M.0000-0002-9871-6490
Jarrett, T.0000-0002-4939-734X
Kewley, L. J.0000-0001-8152-3943
Ogle, P. M.0000-0002-3471-981X
Rich, J. A.0000-0002-5807-5078
Xu, C. K.0000-0002-1588-6700
Yun, M.0000-0001-7095-7543
Alternate Title:Strong Far-IR Cooling Lines, Peculiar CO Kinematics and Possible Star Formation Suppression in Hickson Compact Group 57
Additional Information:© 2014 American Astronomical Society. Received 2014 May 27; accepted 2014 September 20; published 2014 October 28. K.A. thanks Drew Brisbin and Gordon Stacey for giving access to the data and code used to create the [Cii]/COcomparison figure used in this paper and the anonymous referee for insightful recommendations that have improved the paper. K.A. and P.N.A. are supported by funding through Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA, through an award issued by JPL/Caltech. U.L. acknowledges support by the research projects AYA2011-24728 from the Spanish Ministerio de Ciencia y Educaciόn and the Junta de Andalucía (Spain) grants FQM108. T.B. and V.C. acknowledge partial support from the EU FP7 grant PIRSES-GA-2012-316788. The work of L.V.M. has been supported by grant AYA2011-30491-C02-01 cofinanced by MICINN and FEDER funds, and the Junta de Andalucía (Spain) grants P08-FQM-4205 and TIC-114. Support for CARMA construction was derived from the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the James S. McDonnell Foundation, the Associates of the California Institute of Technology, the University of Chicago, the states of California, Illinois, and Maryland, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement and by the CARMA partner universities. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. This work is based (in part) on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Ministerio de Ciencia y Educaciόn (MEC)AYA2011-24728
Junta de AndalucíaFQM108
Marie Curie FellowshipPIRSES-GA-2012-316788
Ministerio de Economía y Competitividad (MCINN)AYA2011-30491-C02-01
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
Junta de AndalucíaP08-FQM-4205
Junta de AndalucíaTIC-114
Gordon and Betty Moore FoundationUNSPECIFIED
Kenneth T. and Eileen L. Norris FoundationUNSPECIFIED
James S. McDonnell FoundationUNSPECIFIED
Caltech AssociatesUNSPECIFIED
University of ChicagoUNSPECIFIED
State of CaliforniaUNSPECIFIED
State of IllinoisUNSPECIFIED
State of MarylandUNSPECIFIED
Subject Keywords:galaxies: evolution – galaxies: individual (NGC 3753, NGC 3754) – galaxies: kinematics and dynamics – galaxies: star formation
Issue or Number:2
Record Number:CaltechAUTHORS:20141013-123551131
Persistent URL:
Official Citation:Strong Far-infrared Cooling Lines, Peculiar CO Kinematics, and Possible Star-formation Suppression in Hickson Compact Group 57 K. Alatalo et al. 2014 ApJ 795 159
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50353
Deposited By: Ruth Sustaita
Deposited On:13 Oct 2014 23:15
Last Modified:04 Nov 2019 00:34

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