Spectral Evolution of the X-Ray Remnant of SN 1987A: A High-resolution Chandra HETG Study
Abstract
Based on observations with the Chandra X-ray Observatory, we present the latest spectral evolution of the X-ray remnant of SN 1987A (SNR 1987A). We present a high-resolution spectroscopic analysis using our new deep (~312 ks) Chandra HETG observation taken in 2018 March as well as archival Chandra grating spectroscopic data taken in 2004, 2007, and 2011 with similarly deep exposures (~170-350 ks). We perform detailed spectral model fits to quantify changing plasma conditions over the last 14 yr. Recent changes in electron temperatures and volume-emission measures suggest that the shocks moving through the inner ring have started interacting with less dense circumstellar material, probably beyond the inner ring. We find significant changes in the X-ray line-flux ratios (among H- and He-like Si and Mg ions) in 2018, consistent with changes in the thermal conditions of the X-ray-emitting plasma that we infer based on the broadband spectral analysis. Post-shock electron temperatures suggested by line-flux ratios are in the range ~0.8-2.5 keV as of 2018. We do not yet observe any evidence of substantial abundance enhancement, suggesting that the X-ray emission component from the reverse-shocked metal-rich ejecta is not yet significant in the observed X-ray spectrum.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2021
- DOI:
- 10.3847/1538-4357/ac249a
- arXiv:
- arXiv:2109.02881
- Bibcode:
- 2021ApJ...922..140R
- Keywords:
-
- 1667;
- 1668;
- 241;
- 847;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- Accepted for publication by ApJ. 23 pages, 14 figures, and 3 tables