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Shock-Enhanced C^+ Emission and the Detection of H_2O from the Stephan's Quintet Group-Wide Shock using Herschel

Appleton, P. N. and Guillard, P. and Boulanger, F. and Cluver, M. E. and Ogle, P. and Falgarone, E. and Pineau des Forêts, G. and O'Sullivan, E. and Duc, P.-A. and Gallagher, S. and Gao, Y. and Jarrett, T. and Konstantopoulos, I. and Lisenfeld, U. and Lord, S. and Lu, N. and Peterson, B. W. and Struck, C. and Sturm, E. and Tuffs, R. and Valchanov, I. and van der Werf, P. and Xu, K. C. (2013) Shock-Enhanced C^+ Emission and the Detection of H_2O from the Stephan's Quintet Group-Wide Shock using Herschel. Astrophysical Journal, 777 (1). Art. No. 66. ISSN 0004-637X.

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We present the first Herschel spectroscopic detections of the [OI]63µm and [CII]158µm fine-structure transitions, and a single para-H_2O line from the 35 x 15 kpc^2 shocked intergalactic filament in Stephan's Quintet. The filament is believed to have been formed when a high-speed intruder to the group collided with clumpy intergroup gas. Observations with the PACS spectrometer provide evidence for broad (> 1000 km s^(-1)) luminous [CII] line profiles, as well as fainter [OI]63µm emission. SPIRE FTS observations reveal water emission from the p-H_2O (1_(11)-0_(00)) transition at several positions in the filament, but no other molecular lines. The H_2O line is narrow, and may be associated with denser intermediate-velocity gas experiencing the strongest shock-heating. The [CII]/PAH_(tot) and [CII]/FIR ratios are too large to be explained by normal photo-electric heating in PDRs. HII region excitation or X-ray/Cosmic Ray heating can also be ruled out. The observations lead to the conclusion that a large fraction the molecular gas is diffuse and warm. We propose that the [CII], [OI] and warm H_2 line emission is powered by a turbulent cascade in which kinetic energy from the galaxy collision with the IGM is dissipated to small scales and low-velocities, via shocks and turbulent eddies. Low-velocity magnetic shocks can help explain both the [CII]/[OI] ratio, and the relatively high [CII]/H_2 ratios observed. The discovery that [CII] emission can be enhanced, in large-scale turbulent regions in collisional environments has implications for the interpretation of [CII] emission in high-z galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Appleton, P. N.0000-0002-7607-8766
Guillard, P.0000-0002-2421-1350
Cluver, M. E.0000-0002-9871-6490
Ogle, P.0000-0002-3471-981X
Gao, Y.0000-0003-0007-2197
Jarrett, T.0000-0002-4939-734X
Konstantopoulos, I.0000-0003-2177-0146
Lisenfeld, U.0000-0002-9471-5423
Lu, N.0000-0002-8948-1044
Struck, C.0000-0002-6490-2156
van der Werf, P.0000-0001-5434-5942
Xu, K. C.0000-0002-1588-6700
Alternate Title:Shock-Enhanced C^+ Emission and the Detection of H_2O from Stephan Quintet's Group-Wide Shock using Herschel
Additional Information:© 2013 American Astronomical Society. Received 2013 April 3; accepted 2013 September 4; published 2013 October 17. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. P.N.A. acknowledges interesting discussions with P. Goldsmith and W. Langer (JPL) regarding [C ii] emission in the Galaxy. 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. The authors thanks an anonymous referee for thoughtful comments on a previous version of the text.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:galaxies: groups: individual (Stephan's Quintet); infrared: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20130925-124214023
Persistent URL:
Official Citation:Shock-enhanced C+ Emission and the Detection of H2O from the Stephan's Quintet Group-wide Shock Using Herschel P. N. Appleton et al. 2013 ApJ 777 66
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41530
Deposited By: Ruth Sustaita
Deposited On:25 Sep 2013 21:35
Last Modified:16 Nov 2019 00:58

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