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Published March 10, 2018 | Version Published + Accepted Version
Journal Article Open

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

Creators

  • 1. ROR icon University of Wisconsin–Eau Claire
  • 2. ROR icon Infrared Processing and Analysis Center
  • 3. ROR icon National Autonomous University of Mexico
  • 4. ROR icon Institut d'Astrophysique de Paris
  • 5. ROR icon Sorbonne University
  • 6. ROR icon Carnegie Observatories
  • 7. ROR icon Space Telescope Science Institute
  • 8. ROR icon University of the Western Cape
  • 9. ROR icon Observatory of Strasbourg
  • 10. ROR icon Western University
  • 11. ROR icon Purple Mountain Observatory
  • 12. ROR icon University of Cape Town
  • 13. ROR icon Arizona State University
  • 14. ROR icon University of Granada
  • 15. ROR icon National Astronomical Observatories
  • 16. ROR icon Chinese Academy of Science South America Center for Astronomy
  • 17. ROR icon University of Paris-Saclay
  • 18. ROR icon Paris Observatory
  • 19. ROR icon Leiden University

Abstract

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.

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.

Attached Files

Published - Peterson_2018_ApJ_855_141.pdf

Accepted Version - 1801.10230

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Peterson_2018_ApJ_855_141.pdf

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Additional details

Identifiers

Eprint ID
85481
Resolver ID
CaltechAUTHORS:20180328-133308085

Related works

Describes
https://arxiv.org/abs/1801.10230 (URL)

Funding

European Space Agency (ESA)
NASA/JPL/Caltech
UW-Barron County Foundation
Ministerio de Economía y Competitividad (MINECO)
AYA2014-53506-P
Fondo Europeo de Desarrollo Regional (FEDER)
Junta de Andalucía
FQM108
China National R&D Program
2017YFA0402704
National Natural Science Foundation of China
11673028
National Natural Science Foundation of China
11420101002
Chinese Academy of Sciences

Dates

Created
2018-03-29
Created from EPrint's datestamp field
Updated
2021-11-15
Created from EPrint's last_modified field

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Caltech groups
Infrared Processing and Analysis Center (IPAC)