Chandra X-Ray Imaging and Spatially Resolved Spectroscopy of SN 1987A: Energy-Dependent Morphology of the Equatorial Ring

Yusuke Sakai; Shinya Yamada; Koji Mori; Hiromasa Suzuki; Haruka Sakemi; Tsukasa Matsushima; Shintaro Kaneko; Kai Matsunaga; Shogo B. Kobayashi; Haruto Aoki; Toshiki Sato

doi:10.3847/1538-4357/ae7c72

arXiv · 2607.06302

Chandra X-Ray Imaging and Spatially Resolved Spectroscopy of SN 1987A: Energy-Dependent Morphology of the Equatorial Ring

Yusuke Sakai·Shinya Yamada·Koji Mori·Hiromasa Suzuki·Haruka Sakemi·Tsukasa Matsushima·Shintaro Kaneko·Kai Matsunaga·Shogo B. Kobayashi·Haruto Aoki·Toshiki Sato

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Abstract

We present a systematic imaging and spatially resolved spectral study of SN 1987A using Chandra observations obtained between 1999 and 2025. By combining multiepoch ACIS and HETG data, we investigate the long-term evolution of the remnant in both the soft and hard X-ray bands. To characterize the radial structure, we model the projected emission with a torus profile and derive its radius and width on the image plane. We find an energy dependence in the ring morphology: while the soft and hard bands exhibit similar structures at early epochs, the soft-band emission becomes systematically broader than the hard-band emission after the early 2010s. Furthermore, when considering the radius and width together, the soft-band emission shows an inward extension, suggesting an increasing contribution from interior and/or high-latitude emission components. The flux evolution of the Fe K line is consistent with previous XMM-Newton results, and we detect its presence already in earlier epochs (~2007-2009) using combined Chandra spectra. Spatially resolved analysis further indicates that the Fe K emission is enhanced in the eastern region. These results provide a unified view of the long-term morphological and spectral evolution of SN 1987A and highlight the emergence of energy-dependent radial structure as a key feature in its late-time evolution.

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Yusuke Sakai, Shinya Yamada, Koji Mori, Hiromasa Suzuki, Haruka Sakemi, Tsukasa Matsushima, Shintaro Kaneko, Kai Matsunaga, Shogo B. Kobayashi, Haruto Aoki, Toshiki Sato. 2026-07-07. Chandra X-Ray Imaging and Spatially Resolved Spectroscopy of SN 1987A: Energy-Dependent Morphology of the Equatorial Ring. https://doi.org/10.3847/1538-4357/ae7c72

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