SNR radio spectral index distribution and its correlation with polarization: a case study of Lupus Loop

TL;DR

This study analyzes the Lupus Loop supernova remnant using radio surveys at multiple frequencies, revealing a correlation between spectral index distribution and polarization, which aids in understanding the interstellar medium.

Contribution

It introduces a new method for determining the borders and properties of Galactic radio sources and demonstrates the correlation between spectral index and polarization in Lupus Loop.

Findings

Confirmed the non-thermal radiation nature of Lupus Loop

Found a significant correlation between spectral index and polarized intensity

Provided detailed distribution of spectral index across the remnant

Abstract

We use radio-continuum all-sky surveys at 1420 and 408 MHz with the aim to investigate properties of the Galactic radio source Lupus Loop. The survey data at 1435 MHz, with the linear polarization of the southern sky, is also used. We calculate properties of this supernova remnant: the brightness temperature, surface brightness and radio spectral index. For determining borders and calculation of its properties, we use the method we have developed. The non-thermal nature of its radiation is confirmed. The distribution of spectral index over its area is also given. A significant correlation between the radio spectral index distribution and the corresponding polarized intensity distribution inside the loop borders is found, indicating that the polarization maps could provide us information about the distribution of interstellar medium, and thus could represent one additional way to search for new Galactic loops.