The XRISM first-light observation: Velocity structure and thermal properties of the supernova remnant N 132D
Authors:   XRISM Collaboration, Audard Marc , Awaki Hisamitsu , Ballhausen Ralf , Bamba Aya , Behar Ehud , Boissay-Malaquin Rozenn , Brenneman Laura , Brown Gregory V , Corrales Lia , Costantini Elisa , Cumbee Renata , Diaz-Trigo Maria , Done Chris , Dotani Tadayasu , Ebisawa Ken , Eckart Megan , Eckert Dominique , Enoto Teruaki , Eguchi Satoshi , Ezoe Yuichiro , Foster Adam , Fujimoto Ryuichi , Fujita Yutaka , Fukazawa Yasushi , Fukushima Kotaro , Furuzawa Akihiro , Gallo Luigi , García Javier A , Gu Liyi , Guainazzi Matteo , Hagino Kouichi , Hamaguchi Kenji , Hatsukade Isamu , Hayashi Katsuhiro , Hayashi Takayuki , Hell Natalie , Hodges-Kluck Edmund , Hornschemeier Ann , Ichinohe Yuto , Ishida Manabu , Ishikawa Kumi , Ishisaki Yoshitaka , Kaastra Jelle , Kallman Timothy , Kara Erin , Katsuda Satoru , Kanemaru Yoshiaki , Kelley Richard , Kilbourne Caroline , Kitamoto Shunji , Kobayashi Shogo , Kohmura Takayoshi , Kubota Aya , Leutenegger Maurice , Loewenstein Michael , Maeda Yoshitomo , Markevitch Maxim , Matsumoto Hironori , Matsushita Kyoko , McCammon Dan , McNamara Brian , Mernier François , Miller Eric D , Miller Jon M , Mitsuishi Ikuyuki , Mizumoto Misaki , Mizuno Tsunefumi , Mori Koji , Mukai Koji , Murakami Hiroshi , Mushotzky Richard , Nakajima Hiroshi , Nakazawa Kazuhiro , Ness Jan-Uwe , Nobukawa Kumiko , Nobukawa Masayoshi , Noda Hirofumi , Odaka Hirokazu , Ogawa Shoji , Ogorzalek Anna , Okajima Takashi , Ota Naomi , Paltani Stephane , Petre Robert , Plucinsky Paul , Porter Frederick Scott , Pottschmidt Katja , Sato Kosuke , Sato Toshiki , Sawada Makoto , Seta Hiromi , Shidatsu Megumi , Simionescu Aurora , Smith Randall , Suzuki Hiromasa , Szymkowiak Andrew , Takahashi Hiromitsu , Takeo Mai , Tamagawa Toru , Tamura Keisuke , Tanaka Takaaki , Tanimoto Atsushi , Tashiro Makoto , Terada Yukikatsu , Terashima Yuichi , Tsuboi Yohko , Tsujimoto Masahiro , Tsunemi Hiroshi , Tsuru Takeshi G , Uchida Hiroyuki , Uchida Nagomi , Uchida Yuusuke , Uchiyama Hideki , Ueda Yoshihiro , Uno Shinichiro , Vink Jacco , Watanabe Shin , Williams Brian J , Yamada Satoshi , Yamada Shinya , Yamaguchi Hiroya , Yamaoka Kazutaka , Yamasaki Noriko , Yamauchi Makoto , Yamauchi Shigeo , Yaqoob Tahir , Yoneyama Tomokage , Yoshida Tessei , Yukita Mihoko , Zhuravleva Irina , Agarwal Manan , Ohshiro Yuken 
Published: October 2024

Abstract
We present an initial analysis of the X-Ray Imaging and Spectroscopy Mission (XRISM) first-light observation of the supernova remnant (SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band, which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of $\sigma _v \sim 450$ km s$^{-1}$. However, the Fe He$\alpha$ lines are substantially broadened with $\sigma _v \sim 1670$ km s$^{-1}$. This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He$\alpha$ emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be $-1000 \lesssim V_{\rm rs}$ (km s$^{-1}$) $\lesssim 3300$ (in the observer frame). We also find that Fe Ly$\alpha$ emission is redshifted with a bulk velocity of $\sim 890$ km s$^{-1}$, substantially larger than the radial velocity of the local interstellar medium surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.