Twofluid models of cosmic ray modified radiative shocks
Abstract
Aims.We demonstrate that cosmic rays suppress the thermal overstability of radiative shocks for a wide range of upstream parameters and initial conditions.
Methods: .We perform onedimensional timedependent twofluid simulations, introducing cosmic rays into overstable radiative shocks.
Results: .When a cosmic ray fluid is introduced, the oscillations of the shock front are damped and a smooth cosmic ray modified shock develops and propagates away from the cold dense layer. A large increase in cosmic ray pressure occurs for lower Mach numbers in radiative cosmic ray modified shocks than in adiabatic cosmic ray modified shocks. The compression ratio is limited to 7 and steady solutions do not exhibit a cold dense layer like those in radiative shocks that are not modified by cosmic rays. If the diffusion length is much larger than the cooling length, the shock is nearly isothermal. The structure of such shocks obtained with the twofluid code agree well with analytically derived solutions for strictly isothermal flow containing cosmic rays.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 June 2006
 DOI:
 10.1051/00046361:20064885
 Bibcode:
 2006A&A...452..763W
 Keywords:

 shock waves;
 ISM: cosmic rays;
 hydrodynamics;
 instabilities;
 ISM: supernova remnants