Expansion of the youngest galactic supernova remnant g1.9+0.3

Abstract

We present a measurement of the expansion and brightening of G1.9 + 0.3, the youngest Galactic supernova remnant (SNR), comparing Chandra X-ray images obtained in 2007 and 2009. A simple uniform-expansion model describes the data well, giving an expansion rate of 0.642%±0.049%yr-1 and a flux increase of 1.7%±1.0%yr-1. Without deceleration, the remnant age would then be 156±11yr, consistent with earlier results. Since deceleration must have occurred, this age is an upper limit; we estimate an age of about 110yr or an explosion date of about 1900. The flux increase is comparable to reported increases at radio wavelengths. G1.9+0.3 is the only Galactic SNR increasing in flux, with implications for the physics of electron acceleration in shock waves. © 2011. The American Astronomical Society. All rights reserved.