Speaker
Description
We investigated the structural characteristics of G7.7-3.7 at a higher resolution of 1284 MHz. Our MeerKAT observations revealed that G7.7-3.7 has an almost circular structure with filamentary features and various blowouts. The western boundary shows a strong bright blowout, while the southern perimeter showcases extended bright filaments with feather-like structures, seemingly disconnected from the western blowout. Moreover, the eastern region shows a blowout centered around a bright point source, with faint, elongated filaments extending north-west. These filaments connect the eastern point source to the western blowout, creating a uniform outward progression. Spectral index analysis indicates a steep spectrum ($\alpha$ ranging $\sim$ 0 to $\sim$ -3), indicating a combination of synchrotron and a few traces of thermal emissions concentrated at the edges of bright blowouts. Analysis of MeerKAT and VLA data, revealed that G7.7-3.7 has expanded by 9 ± 0.45 arcsec over a period of 31.907 yr, corresponding to an expansion rate of 0.282 ± 0.014 arcsec yr$^{-1}$. This expansion indicates a shock speed of 5883 ± 294 km s$^{-1}$ and an age of 1090 ± 77 yrs, suggesting that G7.7-3.7 have entered the Sedov-Taylor phase with an age > 1000 yrs and shock speed > 5500 km s$^{-1}$. The multi-wavelength investigation unveiled a distinctive structure within the southern radio blowout, encompassing a bright radio blowout, a prominent X-ray arc and two faint optical filaments aligned with the X-ray bright arc. We attribute the bright radio blowouts to inhomogeneous mass outflow from shock-accelerated particles and the weakening of magnetic fields along its perimeter. Traces of thermal emissions, especially along the edges of blowouts, are likely due to shock-heated gas, which intensifies in the southern region amid high-density Interstellar Medium (ISM). Therefore, these results support a scenario in which the progenitor supernova of G7.7-3.7 exploded within ISM of varying density, generating the observed X-ray emissions and faint optical filaments. Our findings provide valuable insights into the dynamics and evolution of supernova remnants.
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