Synthetic X-ray and radio maps for two different models of Stephan's Quintet

Abstract

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 smoothed particle magnetohydrodynamics (SPMHD) method. We adapt two different initial models for SQ based on Renaud et al. and Hwang et al., 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 Renaud et al., whose galaxies are more massive, whereas the less massive SQ model based on Hwang et al. 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 Renaud et al., whereas the distribution and structure of the synchrotron emission is better reproduced by the SQ model based on Hwang et al..

20 pages, 15 figures, accepted to MNRAS

References in corpus (7)

• Smoothed Particle Hydrodynamics and Magnetohydrodynamics
• The effect of galaxy mass ratio on merger--driven starbursts
• Equal- and unequal-mass mergers of disk and elliptical galaxies with black holes
• Powerful High Velocity-Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet
• A Global Probe of Cosmic Magnetic Fields to High Redshifts
• Turbulent molecular gas and star formation in the shocked intergalactic medium of Stephan's Quintet
• A divergence-cleaning scheme for cosmological SPMHD simulations

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• Strong magnetic fields and large rotation measures in protogalaxies by supernova seeding
• On the magnetic fields in voids
• Magnetic buoyancy in simulated galactic discs with a realistic circum galactic medium
• On the origin of magnetic driven winds and the structure of the galactic dynamo in isolated galaxies
• Intergalactic magnetic fields in Stephan's Quintet
• SPMHD simulations of Structure Formation
• A large-scale, regular intergalactic magnetic field associated with Stephan's Quintet?
• Redshift effects implications on revised models of Stephan's quintet