Annette Geng, Alexander M. Beck, Klaus Dolag, Florian Bürzle, Marcus C. Beck, Hanna Kotarba, Peter Nielaba
We present simulations of the compact galaxy group Stephan's Quintet (SQ) including magnetic fields, performed with the N-body/smoothed particle hydrodynamics (SPH) code \textsc{Gadget}. The simulations include radiative cooling, star formation and supernova feedback. Magnetohydrodynamics (MHD) is implemented using the standard SPMHD method. We adapt two different initial models for SQ based on \citet{ReAp10} and \citet{HwSt12}, both including four galaxies (NGC 7319, NGC 7320c, NGC 7318a and NGC 7318b). Additionally, the galaxies are embedded in a magnetized, low density intergalactic medium (IGM). The ambient IGM has an initial magnetic field of $10^{-9}$ G and the four progenitor discs have initial magnetic fields of $10^{-9} - 10^{-7}$ G. We investigate the morphology, regions of star formation, temperature, X-ray emission, magnetic field structure and radio emission within the two different SQ models. In general, the enhancement and propagation of the studied gaseous properties (temperature, X-ray emission, magnetic field strength and synchrotron intensity) is more efficient for the SQ model based on \citet{ReAp10}, whose galaxies are more massive, whereas the less massive SQ model based on \citet{HwSt12} shows generally similar effects but with smaller efficiency. We show that the large shock found in observations of SQ is most likely the result of a collision of the galaxy NGC 7318b with the IGM. This large group-wide shock is clearly visible in the X-ray emission and synchrotron intensity within the simulations of both SQ models. The order of magnitude of the observed synchrotron emission within the shock front is slightly better reproduced by the SQ model based on \citet{ReAp10}, whereas the distribution and structure of the synchrotron emission is better reproduced by the SQ model based on \citet{HwSt12}.
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http://arxiv.org/abs/1206.1234
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