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Title: Discovery of enhanced radiative recombination continua of He-like iron and calcium from IC 443 and its implications

We present deep observations of the Galactic supernova remnant IC 443 with the Suzaku X-ray satellite. We find prominent K-shell lines from iron and nickel, together with a triangle residual at 8-10 keV, which corresponds to the energy of the radiative recombination continuum (RRC) of He-like iron. In addition, the wavy residuals have been seen at ∼5.1 and ∼5.5 keV. We confirm that the residuals show the first enhanced RRCs of He- and H-like calcium found in supernova remnants. These facts provide robust evidence for the recombining plasma. We reproduce the plasma in the 3.7-10 keV band using a recombining plasma model at the electron temperature 0.65 keV. The recombination parameter n {sub e} t (n {sub e} is electron density and t is elapsed time after formation of a recombining plasma) and abundances of iron and nickel are strongly correlated, and hence the errors are large. On the other hand, the ratio of nickel to iron relative to the solar abundances is well constrained to 11{sub −3}{sup +4} (1σ). A possibility is that the large abundance ratio is a result of an asymmetric explosion of the progenitor star.
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Division of Physics and Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
  2. Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan)
  3. Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe 5-10-1, Sagamihara, Kanagawa 252-5258 (Japan)
Publication Date:
OSTI Identifier:
22351481
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ASYMMETRY; CALCIUM; ELECTRON DENSITY; ELECTRON TEMPERATURE; ERRORS; EXPLOSIONS; GALAXIES; IRON; K SHELL; KEV RANGE; NICKEL; PLASMA; RECOMBINATION; SATELLITES; STARS; SUPERNOVA REMNANTS; X RADIATION