On the Expansion, Age, and Origin of the Puzzling Shell/Pulsar Wind Nebula G310.6-1.6

TL;DR

This study uses Chandra X-ray observations to analyze the supernova remnant G310.6-1.6, revealing its age, expansion properties, and challenging existing models of its origin and evolution.

Contribution

It provides new constraints on the remnant's age, expansion velocity, and the nature of its shell, suggesting an unusually low-energy supernova or alternative formation scenarios.

Findings

Remnant's age is at least 2500 years.

Shell expansion is below 1000 km/s.

Thermal emission from the shell is severely limited.

Abstract

We present a 142-ks Chandra observation of the enigmatic combination supernova remnant G310.6-1.6 consisting of a bright pulsar-wind nebula driven by an energetic pulsar, surrounded by a highly circular, very faint shell with a featureless, probably synchrotron, spectrum. Comparison with an observation 6 years earlier shows no measurable expansion of the shell, though some features in the pulsar-wind nebula have moved. We find an expansion age of at least 2500 yr, implying a current shock velocity less than about 1000 km/s. We place severe upper limits on thermal emission from the shell; if the shell locates the blast wave, a Sedov interpretation would require the remnant to be very young, about 1000 yr, and to have resulted from a dramatically sub-energetic supernova, ejecting << 0.02 M_sun with energy E < 3 x 10^47 erg. Even a merger-induced collapse of a white dwarf to a neutron star, with a low-energy explosion, is unlikely to produce such an event. Other explanations seem equally unlikely.