A kinematic study of central compact objects and their host supernova remnants

Vol. 651
7. Stellar structure and evolution

A kinematic study of central compact objects and their host supernova remnants

by M. G. F. Mayer and W. Becker 2021, A&A, 651, A40

Supernova remnants (SNRs) are the leftovers of supernovae, the results of powerful explosions. In the beginning, their gas expands at ~20,000 km/s. This velocity decreases with time, depending on the density of the surrounding ambient medium, which is snowplowed away. For relatively young SNRs, such as the ones considered in this study (~350 to 27,000 yr), one could expect expansion velocities of ~5,000 km/s. Naively, one might imagine that SNRs do not change on timescales of a human lifetime. However, if observed at high angular resolution (as Chandra observations allow for) and over a sufficiently long temporal base (~10 yr), they can reveal their overall expansion, similar to that of an inflating balloon. A meticulous analysis of the X-ray data is needed to put this expansion on a firm statistical basis. This is done in the work by Meyer and Becker, which has revealed a hint of SNR expansion in two remnants. In addition, the authors were also able to measure or constrain the motion of the neutron star, the supernova leftover, excluding hyper-velocity objects..