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X-Ray Emission from the Taffy (VV254) Galaxies and Bridge

Appleton, P. N. and Lanz, L. and Bitsakis, T. and Wang, J. and Peterson, B. W. and Lisenfeld, U. and Alatalo, K. and Guillard, P. and Boulanger, F. and Cluver, M. and Gao, Y. and Helou, G. and Ogle, P. and Struck, C. (2015) X-Ray Emission from the Taffy (VV254) Galaxies and Bridge. Astrophysical Journal, 812 (2). Art. No. 118. ISSN 0004-637X.

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We present the first X-ray observations of the Taffy galaxies (UGC 12914/5) with the Chandra observatory and detect soft X-ray emission in the region of the gas-rich, radio-continuum-emitting Taffy bridge. The results are compared to Herschel observations of dust and diffuse [C ii] line-emitting gas. The diffuse component of the Taffy bridge has an X-ray luminosity of L_(X(0.5-8 keV) = 5.4 × 10^(39) erg s^(−1), which accounts for 19% of the luminosity of the sum for the two galaxies. The total mass in hot gas is (0.8–1.3) × 10^8 M_⊙, which is approximately 1% of the total (H i + H_2) gas mass in the bridge, and ~11% of the mass of warm molecular hydrogen discovered by Spitzer. The soft X-ray and dense CO-emitting gas in the bridge have offset distributions, with the X-rays peaking along the northwestern side of the bridge in the region where stronger far-IR dust and diffuse [C ii] gas is observed by Herschel. We detect nine Ultra Luminous X-ray sources in the system, the brightest of which is found in the bridge, associated with an extragalactic H ii region. We suggest that the X-ray-emitting gas has been shocked—heated to high temperatures and "splashed" into the bridge by the collision. The large amount of gas stripped from the galaxies into the bridge and its very long gas depletion timescale (>10 Gyr) may explain why this system, unlike most major mergers, is not a powerful IR emitter.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Appleton, P. N.0000-0002-7607-8766
Lanz, L.0000-0002-3249-8224
Bitsakis, T.0000-0001-5787-8242
Lisenfeld, U.0000-0002-9471-5423
Alatalo, K.0000-0002-4261-2326
Guillard, P.0000-0002-2421-1350
Cluver, M.0000-0002-9871-6490
Gao, Y.0000-0003-0007-2197
Helou, G.0000-0003-3367-3415
Ogle, P.0000-0002-3471-981X
Struck, C.0000-0002-6490-2156
Additional Information:© 2015. The American Astronomical Society. Received 2015 July 16; accepted 2015 September 15; published 2015 October 14. We thank an anonymous referee for very helpful comments that improved the manuscript. The scientific results reported in this article are based on observations made by the Chandra X-ray Observatory. Support for this work was provided by the National Aeronautics and Space Administration through Chandra Award Number GO3-14087X, issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. The work is also based, in part, on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. Partial support for LL, PA & KA was also provided for Herschel observations, through a contract issued by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Partial support for K.A. was also provided by NASA through Hubble Fellowship grant #HST-HF2-51352.001 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. J.W. acknowledges support from NSFC grants 11443003 and 11473021.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASA Hubble FellowshipHST-HF2-51352.001
National Natural Science Foundation of China11443003
National Natural Science Foundation of China11473021
Subject Keywords:galaxies: individual (UGC 12914, UGC12915, VV254)
Issue or Number:2
Record Number:CaltechAUTHORS:20151218-100045145
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63063
Deposited By: George Porter
Deposited On:18 Dec 2015 23:42
Last Modified:16 Nov 2019 00:56

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