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Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C II] Emission in the Collisionally Formed Bridge

Peterson, B. W. and Appleton, P. N. and Bitsakis, T. and Guillard, P. and Alatalo, K. and Boulanger, F. and Cluver, M. and Duc, P.-A. and Falgarone, E. and Gallagher, S. and Gao, Y. and Helou, G. and Jarrett, T. H. and Joshi, B. and Lisenfeld, U. and Lu, N. and Ogle, P. and Pineau des Forêts, G. and van der Werf, P. and Xu, C. K. (2018) Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C II] Emission in the Collisionally Formed Bridge. Astrophysical Journal, 855 (2). Art. No. 141. ISSN 1538-4357. doi:10.3847/1538-4357/aaac2c.

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Using the PACS and SPIRE spectrometers on board Herschel, we obtained observations of the Taffy galaxies (UGC 12914/12915) and bridge. The Taffy system is believed to be the result of a face-on collision between two gas-rich galaxies, in which the stellar disks passed through each other, but the gas was dispersed into a massive H i and molecular bridge between them. Emission is detected and mapped in both galaxies and the bridge in the [C ii]157.7 μm and [O i]63.2 μm fine-structure lines. Additionally, SPIRE FTS spectroscopy detects the [C i] ^3P_2 → ^3p_1(809.3 GHz) and [C i] ^3P_1 → ^3p_0(492.2 GHz) neutral carbon lines, and weakly detects high-J CO transitions in the bridge. These results indicate that the bridge is composed of a warm multi-phase medium consistent with shock and turbulent heating. Despite low star formation rates in the bridge, the [C ii] emission appears to be enhanced, reaching [C ii]/FIR ratios of 3.3% in parts of the bridge. Both the [C ii] and [O i] lines show broad intrinsic multi-component profiles, similar to those seen in previous CO (1–0) and H i observations. The [C ii] emission shares similar line profiles with both the double-peaked H i profiles and shares a high-velocity component with single-peaked CO profiles in the bridge, suggesting that the [C ii] emission originates in both the neutral and molecular phases. We show that it is feasible that a combination of turbulently heated H_2 and high column-density H i, resulting from the galaxy collision, is responsible for the enhanced [C ii] emission.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Appleton, P. N.0000-0002-7607-8766
Bitsakis, T.0000-0001-5787-8242
Guillard, P.0000-0002-2421-1350
Alatalo, K.0000-0002-4261-2326
Cluver, M.0000-0002-9871-6490
Gao, Y.0000-0003-0007-2197
Helou, G.0000-0003-3367-3415
Jarrett, T. H.0000-0002-4939-734X
Lisenfeld, U.0000-0002-9471-5423
Lu, N.0000-0002-8948-1044
Ogle, P.0000-0002-3471-981X
van der Werf, P.0000-0001-5434-5942
Xu, C. K.0000-0002-1588-6700
Additional Information:© 2018. The American Astronomical Society. Received 2018 January 4; accepted 2018 January 29; published 2018 March 16. This work is based on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. B.W.P. also thanks the UW-BC Foundation for its generous support. U.L. acknowledges support by the research projects AYA2014-53506-P from the Spanish Ministerio de Economía y Competitividad, from the European Regional Development Funds (FEDER) and the Junta de Andalucía (Spain) grants FQM108. N.L. acknowledges support by National Key R&D Program of China, #2017YFA0402704 and NSFC #11673028. Y.G. acknowledges support by National Key R&D Program of China (2017YFA0402704), the NSFC #11420101002 and the CAS Key Research Program of Frontier Sciences.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Space Agency (ESA)UNSPECIFIED
UW-Barron County FoundationUNSPECIFIED
Ministerio de Economía y Competitividad (MINECO)AYA2014-53506-P
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
Junta de AndalucíaFQM108
China National R&D Program2017YFA0402704
National Natural Science Foundation of China11673028
National Natural Science Foundation of China11420101002
Chinese Academy of SciencesUNSPECIFIED
Subject Keywords:galaxies: individual (UGC 12914, UGC 12915) ; galaxies: interactions; intergalactic medium
Issue or Number:2
Record Number:CaltechAUTHORS:20180328-133308085
Persistent URL:
Official Citation:B. W. Peterson et al 2018 ApJ 855 141
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85481
Deposited By: George Porter
Deposited On:29 Mar 2018 15:09
Last Modified:15 Nov 2021 20:29

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