The Interaction of a Supernova Remnant with Background Interstellar Turbulence

Abstract

Supernova explosions are among the most energetic events in the Universe. After the explosion, the material ejected by the supernova expands throughout the interstellar medium (ISM), forming what is called a supernova remnant (SNR). The shocks associated with the expanding SNR are sources of galactic cosmic rays, which can reach energies of the PeV order. The magnetic field plays a key role in these processes. It is known that the ISM is turbulent, with an observed magnetic field of about a few μ G, made by the superposition of a uniform and a fluctuating component. During the SNR expansion, the shock interacts with this turbulent environment, leading to a distortion of the shock front and a compression of the medium. In this work, we use the magnetohydrodynamics PLUTO code to mimic the evolution of the blast wave associated with an SNR. We perform a parametric study varying the level of density and magnetic field fluctuations in the ISM, with the aim of understanding the best parameter values able to reproduce real observations. We introduce a novel analysis technique based on a two-dimensional autocorrelation function C ( ℓ ) and a second-order structure function S _2 ( ℓ ), quantifying the level of anisotropy and the turbulence correlation lengths. By interpolating the autocorrelation function on a polar grid, we extract the power spectra of turbulence at the SNR. Finally, a preliminary comparison with Chandra observations of SN 1006 is also presented.

Keywords

• Supernova remnants
• Interstellar medium
• Magnetohydrodynamical simulations