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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/28288

Title: Shock-Enhanced C+ Emission and the Detection of H2O from Stephan's Quintet's Group-Wide Shock using Herschel
Authors: Appleton, P. N.
Guillard, P.
Boulanger, F.
Cluver, M. E.
Ogle, P. M.
Falgarone, E.
Pineau des Forêts, G.
O'Sullivan, E.
Duc, P.-A.
Gallagher, S.
Gao, Y.
Jarrett, T. H.
Konstantopoulos, I.
Lisenfeld, Ute
Lord, S.
Lu, N.
Peterson, B. W.
Struck, C.
Sturm, E.
Tuffs, Richard J.
Valchanov, I.
Van Der Wer, P.
Xu, C. K.
Issue Date: 2013
Abstract: We present the first Herschel spectroscopic detections of the [OI]63 and [CII]158 micron fine-structure transitions, and a single para-H2O 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]63micron emission. SPIRE FTS observations reveal water emission from the p-H2O (111-000) transition at several positions in the filament, but no other molecular lines. The H2O 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 H2 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]/H2 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.
Keywords: Galaxies
Stephan's Quintet
Galaxy Astrophysics
URI: http://hdl.handle.net/10481/28288
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Appears in Collections:DFTC - Artículos

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