An analysis of the possible thermal emission at radio frequencies from an evolved supernova remnant HB 3 (G132.7 + 1.3): revisited

TL;DR

This study revisits the radio spectrum analysis of supernova remnant HB 3 using corrected flux data, confirming a significant thermal emission component and supporting interaction with nearby molecular clouds.

Contribution

It provides an updated analysis of thermal emission in HB 3 using revised flux densities, reaffirming the thermal component's significance in the radio spectrum.

Findings

Thermal emission contributes approximately 37% at 1 GHz.

Estimated ambient density is about 9 cm^{-3}.

Thermal component estimates are consistent with previous results.

Abstract

It has recently been reported that some of the flux density values for an evolved supernova remnant (SNR) HB 3 (G132.7 + 1.3) are not accurate. In this work we revised an analysis of the possible thermal emission at radio frequencies from the SNR HB 3 using the recently published, corrected, flux density values. A model including a sum of non-thermal (purely synchrotron) and thermal (bremsstrahlung) component is applied for fitting integrated radio spectrum of the SNR. The contribution of thermal component in total volume emissivity at $1 \mathrm{GHz}$ was estimated to be $\approx37 %$. The ambient density was also estimated to be $n\approx 9 \mathrm{cm}^{-3}$ for the $\mathrm{T}=10^{4} \mathrm{K}$. Again, we obtained the relatively significant presence of thermal emission at radio frequencies from the SNR so we could support interaction between SNR HB 3 and adjacent molecular cloud associated with the H {\sc ii} region W3. Our model estimates for thermal component contribution to total volume emissivity at $1 \mathrm{GHz}$ and ambient density are similar to those obtained earlier ($\approx40 %$, $\approx10 \mathrm{cm^{-3}}$). It is clear that the corrected flux density values do not change the basic conclusions.