| Type |
Journal Article |
| Names |
A. Lazarian, D. Pogosyan |
| Publication |
The Astrophysical Journal |
| Volume |
747 |
| Issue |
1 |
| Pages |
5 |
| Date |
March 1, 2012 |
| Short Title |
Statistical Description of Synchrotron Intensity Fluctuations |
| URL |
http://adsabs.harvard.edu/abs/2012ApJ...747....5L |
| Library Catalog |
NASA ADS |
| Abstract |
We provide a theoretical description of synchrotron fluctuations arising
from magnetic turbulence. We derive an expression that relates the
correlation of synchrotron fluctuations for an arbitrary index of
relativistic electrons to the correlations arising from a particular
γ = 2 index that provides synchrotron emissivity proportional to
the squared intensity of perpendicular to the line-of-sight component of
magnetic field. We provide a detailed study of the statistics in the
latter case assuming that the underlying magnetic turbulence is
axisymmetric. We obtain general relations valid for an arbitrary model
of magnetic axisymmetric turbulence and analyze the relations for the
particular example of magnetic turbulence that is supported by numerical
simulations. We predict that the synchrotron intensity fluctuations are
anisotropic with larger correlation present along the direction of
magnetic field. This anisotropy is dominated by the quadrupole component
with the ratio between quadrupole and monopole parts being sensitive to
the compressibility of underlying turbulence. Our work opens avenues for
quantitative studies of magnetic turbulence in our Galaxy and beyond
using synchrotron emission. It also outlines the directions of how
synchrotron foreground emission can be separated from cosmological
signal, i.e., from cosmic microwave background or highly redshifted H I
emission. We also provide the expressions for the synchrotron
polarization (Stokes parameters and their combinations) for the model of
axisymmetric magnetic turbulence. |
| Tags |
ISM: General, ISM: structure, Magnetohydrodynamics: MHD, radio continuum: ISM, turbulence |