Multi-Wavelength Study of Supernova Remnant SN386 (G7.7-3.7)

Abstract

We present a comprehensive multi-wavelength study of Supernova Remnant SN386 (G7.7-3.7), integrating existing observations from radio, X-ray, and optical wavelengths. Radio observations from MOST and VLA reveal a nearly circular shell with extended bright regions in the west and south borders, while MeerKAT observations reveal thin filaments with faint blowouts along the perimeter. The blowouts suggest the localized magnetic field weakening at the boundaries of G7.7-3.7 and non-uniform mass outflow from the progenitor star. The radio emission analysis indicates a flat spectrum, \(\alpha\) \(\simeq\) -0.32, with a steep spectral index, $\alpha$ $\simeq$-0.6, at the west border. MeerKAT polarization studies reveal magnetic field orientation aligned along the filaments rather than the overall shell structure as in MOST. X-ray morphology unveils a non-uniform distribution of X-ray emissions with bright arc-like features corresponding to southern radio emissions. The X-ray spectroscopic analysis shows that the arc-like feature is characterized by under-ionized plasma with low ionization timescale, 2.4 \(^{+1.1}_{-1.3}\) \(\times\) 10 \(^{10}\) cm \(^{-3}\) s, inferring a shocked age of 1.2 ± 0.6 kyr consistent with the supernova of 386 CE. Optical observations reveal filamentary structures aligned in the east-west direction with X-ray emission in H$\alpha$ + [NII], [OIII] and [SII] narrow-band filters. Optical long slit spectroscopy of one filament reveals [SII]/H$\alpha$ = (1.6-2.5) expected for shock-heated SNR and [NII]/H$\alpha$ greater than 2 indicating a gas enriched in nitrogen, suggesting collision with circumstellar material forming optical filaments. The study suggests a multi-faceted nature of G7.7-3.7, with localized weakening of magnetic field on the edges of non-uniform mass outflow, expanding in non-uniform density ISM and interacting with ISM mixed with circumstellar material.