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Title: SHOCK-ENHANCED C{sup +} EMISSION AND THE DETECTION OF H{sub 2}O FROM THE STEPHAN'S QUINTET GROUP-WIDE SHOCK USING HERSCHEL

We present the first Herschel spectroscopic detections of the [O I] 63 μm and [C II] 158 μm fine-structure transitions, and a single para-H{sub 2}O line from the 35 × 15 kpc{sup 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 a clumpy intergroup gas. Observations with the PACS spectrometer provide evidence for broad (>1000 km s{sup –1}) luminous [C II] line profiles, as well as fainter [O I] 63 μm emission. SPIRE FTS observations reveal water emission from the p-H{sub 2}O (1{sub 11}-0{sub 00}) transition at several positions in the filament, but no other molecular lines. The H{sub 2}O line is narrow and may be associated with denser intermediate-velocity gas experiencing the strongest shock-heating. The [C II]/PAH{sub tot} and [C II]/FIR ratios are too large to be explained by normal photo-electric heating in photodissociation regions. H II 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 [C II], [O I], and warm H{sub 2} line emission is powered by a turbulent cascademore » in which kinetic energy from the galaxy collision with the intergalactic medium is dissipated to small scales and low velocities, via shocks and turbulent eddies. Low-velocity magnetic shocks can help explain both the [C II]/[O I] ratio, and the relatively high [C II]/H{sub 2} ratios observed. The discovery that [C II] emission can be enhanced, in large-scale turbulent regions in collisional environments, has implications for the interpretation of [C II] emission in high-z galaxies.« less
Authors:
; ;  [1] ;  [2] ; ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;  [15] ;  [16] more »; « less
  1. NASA Herschel Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
  3. Institut d'Astrophysique Spatialé, Universite Paris Sud 11, Orsay (France)
  4. Australian Astronomical Observatory, Epping, NSW (Australia)
  5. NASA Extragalactic Database, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)
  6. Ecole Normale Supérieure/Observatoire de Paris, F-75231 Paris (France)
  7. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  8. Laboratoire AIM, Saclay, Paris (France)
  9. University of Western Ontario, 1151 Richmond Street, London, Ontario (Canada)
  10. Purple Mountain Observatory, Nanjing (China)
  11. Astronomy Department, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
  12. Universidad de Granada, Granada (Spain)
  13. University of Wisconsin-Barron County, Rice Lake, WI 54868 (United States)
  14. Iowa State University, Ames, IA 50011 (United States)
  15. Max Planck Institute fur Extraterrestische Physik, Munich (Germany)
  16. MPI-Kernphysik, Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22270635
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CARBON IONS; COSMIC RADIATION; EXCITATION; FILAMENTS; FINE STRUCTURE; GALAXIES; H2 REGIONS; KINETIC ENERGY; POLYCYCLIC AROMATIC HYDROCARBONS; SHOCK HEATING; WATER