The radio expansion and brightening of the very young supernova remnant G1.9+0.3

TL;DR

This paper reports on radio observations of the supernova remnant G1.9+0.3, revealing its rapid expansion and increasing brightness, confirming it as the youngest known Galactic remnant approximately 150 years old.

Contribution

The study provides new high-resolution radio measurements showing the expansion and brightening of G1.9+0.3, establishing it as the youngest Galactic supernova remnant.

Findings

Radio emission has expanded by about 15% over 23 years.

The remnant's outer diameter is approximately 92 arcseconds.

The integrated flux density has been increasing recently.

Abstract

Recent radio observations of the small Galactic supernova remnant G1.9+0.3 made at 4.86 GHz with the VLA are presented, and compared with earlier observations at 1.49 GHz which have a comparable resolution (10 x 4 arcsec^2). These show that the radio emission from this remnant has expanded significantly, by about 15 per cent over 23 years, with a current outer diameter of approximately 92 arcsec. This expansion confirms that G1.9+0.3 is the youngest Galactic remnant yet identified, only about 150 years old at most. Recent, lower resolution, 1.43-GHz observations are also discussed, and the integrated flux densities from these and the 4.86-GHz observations are compared with earlier results. This shows that the integrated flux density of G1.9+0.3 has been increasing recently.