SIMBAD references

2025PASJ...77L...1X - Publ. Astron. Soc. Jap., 77, L1-L8 (2025/February-0)

Overionized plasma in the supernova remnant Sagittarius A East anchored by XRISM observations.

XRISM COLLABORATION, AUDARD M., AWAKI H., BALLHAUSEN R., BAMBA A., BEHAR E., BOISSAY-MALAQUIN R., BRENNEMAN L., BROWN G.V., CORRALES L., COSTANTINI E., CUMBEE R., DIAZ-TRIGO M., DONE C., DOTANI T., EBISAWA K., ECKART M., ECKERT D., ENOTO T., EGUCHI S., EZOE Y., FOSTER A., FUJIMOTO R., FUJITA Y., FUKAZAWA Y., FUKUSHIMA K., FURUZAWA A., GALLO L., GARCIA J.A., GU L., GUAINAZZI M., HAGINO K., HAMAGUCHI K., HATSUKADE I., HAYASHI K., HAYASHI T., HELL N., HODGES-KLUCK E., HORNSCHEMEIER A., ICHINOHE Y., ISHIDA M., ISHIKAWA K., ISHISAKI Y., KAASTRA J., KALLMAN T., KARA E., KATSUDA S., KANEMARU Y., KELLEY R., KILBOURNE C., KITAMOTO S., KOBAYASHI S., KOHMURA T., KUBOTA A., LEUTENEGGER M., LOEWENSTEIN M., MAEDA Y., MARKEVITCH M., MATSUMOTO H., MATSUSHITA K., McCAMMON D., McNAMARA B., MERNIER F., MILLER E.D., MILLER J.M., MITSUISHI I., MIZUMOTO M., MIZUNO T., MORI K., MUKAI K., MURAKAMI H., MUSHOTZKY R., NAKAJIMA H., NAKAZAWA K., NESS J.-U., NOBUKAWA K., NOBUKAWA M., NODA H., ODAKA H., OGAWA S., OGORZALEK A., OKAJIMA T., OTA N., PALTANI S., PETRE R., PLUCINSKY P., PORTER F.S., POTTSCHMIDT K., SATO K., SATO T., SAWADA M., SETA H., SHIDATSU M., SIMIONESCU A., SMITH R., SUZUKI H., SZYMKOWIAK A., TAKAHASHI H., TAKEO M., TAMAGAWA T., TAMURA K., TANAKA T., TANIMOTO A., TASHIRO M., TERADA Y., TERASHIMA Y., TSUBOI Y., TSUJIMOTO M., TSUNEMI H., TSURU T.G., UCHIDA H., UCHIDA N., UCHIDA Y., UCHIYAMA H., UEDA Y., UNO S., VINK J., WATANABE S., WILLIAMS B.J., YAMADA S., YAMADA S., YAMAGUCHI H., YAMAOKA K., YAMASAKI N., YAMAUCHI M., YAMAUCHI S., YAQOOB T., YONEYAMA T., YOSHIDA T., YUKITA M., ZHURAVLEVA I., WANG Q.D., AMANO Y., TANAKA K., NARITA T., OHSHIRO Y., YOSHIMOTO A., AOKI Y. and BALAKRISHNAN M.

Abstract (from CDS):

Sagittarius A East is a supernova remnant with a unique surrounding environment, as it is located in the immediate vicinity of the supermassive black hole at the Galactic center, Sagittarius A $^{*}$ . The X-ray emission of the remnant is suspected to show features of overionized plasma, which would require peculiar evolutionary paths. We report on the first observation of Sagittarius A East with the X-Ray Imaging and Spectroscopy Mission (XRISM). Equipped with a combination of a high-resolution microcalorimeter spectrometer and a large field-of-view CCD imager, we for the first time resolved the Fe XXV K-shell lines into fine structure lines and measured the forbidden-to-resonance intensity ratio to be $1.39 \pm 0.12$ , which strongly suggests the presence of overionized plasma. We obtained a reliable constraint on the ionization temperature just before the transition into the overionization state, of $\gt\! 4\:$ keV. The recombination timescale was constrained to be $\lt\! 8 \times 10^{11} \:$ cm $^{-3}\:$ s. The small velocity dispersion of $109 \pm 6\:$ km $\:$ s $^{-1}$ indicates a low Fe ion temperature $\lt\! 8\:$ keV and a small expansion velocity $\lt\! 200\:$ km $\:$ s $^{-1}$ . The high initial ionization temperature and small recombination timescale suggest that either rapid cooling of the plasma via adiabatic expansion from dense circumstellar material or intense photoionization by Sagittarius A $^{*}$ in the past may have triggered the overionization.

Abstract Copyright: © The Author(s) 2024. Published by Oxford University Press on behalf of the Astronomical Society of Japan.

Journal keyword(s): Galaxy: center - ISM: individual objects (Sagittarius A East) - ISM: supernova remnants - X-rays: ISM

Simbad objects: 5

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