X-ray Evolution of SNR 1987A: The Radial Expansion

TL;DR

This paper analyzes a decade of Chandra X-ray observations to measure the radial expansion of SNR 1987A, identifying the transition from free expansion to the adiabatic phase and comparing it with theoretical predictions.

Contribution

It introduces empirical models to accurately measure the remnant's complex structure and track its evolution over time.

Findings

End of free expansion phase identified

Transition to adiabatic phase observed

Expansion timing matches early theoretical predictions

Abstract

We present the evolution of the radial expansion of SNR 1987A as measured using Chandra X-ray observations taken over the last 10 years. To characterize the complex structure of the remnant and isolate the expansion measurement, we fit the images to several empirical models including: a simple circular torus, a torus with bilateral lobes, and a torus with four tangentially extended lobes. We discuss the results of this measure in the context of the overall evolution of the supernova remnant, for which we believe we have measured the end of the free expansion phase and its transition to the adiabatic phase (at least along the equatorial ring). The timing of this event is in agreement with early predictions of the remnant evolution.