Driving Galactic Turbulence by Supernova Explosions |
| |
| Authors: | Korpi Maarit J Brandenburg A Tuominen I |
| |
| Institution: | (1) Dept. of Phys. Sci., Astronomy Division, University of Oulu, Finland.;(2) Dept. of Mathem., University of Newcastle upon Tyne, U.K. |
| |
| Abstract: | We investigate the general properties of supernova driven interstellar turbulence using local three-dimensional MHD simulations under Galactic conditions. Our model includes the effects of large-scale shear due to Galactic differential rotation, density stratification, compressibility, magnetic fields, heating via supernova explosions and parameterized radiative cooling of the interstellar medium. In addition to investigating isolated supernova explosions we allow for multiple supernovae distributed randomly in the Galactic disc and exponentially in the vertical direction. Single supernova explosions drive a strong shock, the lifetime of which is approximately 2 Myr in our model. This stage is found to be characterized by a kinetic energy spectrum in the diffuse gas with spectral index consistent with k = –2. Large-scale shear and Coriolis force act on the supernova remnant producing some vorticity inside it, but this process was found to be very weak. In the case of multiple supernova explosions, older remnants have an important role causing density fluctuations in the interstellar medium. In this  clumpy medium, the propagation velocity of the shock fronts changes due to the changing density, and vorticity is generated. In the absence of these supernova interactions the kinetic energy spectrum shows a relatively wide shock spectrum with spectral index k = –2, but when the supernova interactions become dominant the classical k = –5/3 spectrum is observed. |
| |
| Keywords: | Interstellar turbulence supernova explosions |
| 本文献已被 SpringerLink 等数据库收录！ |
|
