DISCOVERY OF STRONG RADIATIVE RECOMBINATION CONTINUA FROM THE SUPERNOVA REMNANT IC 443 WITH SUZAKU

Journal Article · Sun Nov 01 04:00:00 EST 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/705/1/L6· OSTI ID:21378427

Yamaguchi, H; Hiraga, J S ^[1]; Ozawa, M; Koyama, K ^[2]; Masai, K ^[3]; Ozaki, M ^[4]; Yonetoku, D ^[5]

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1. RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2. Department of Physics, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
3. Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan)
4. Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)
5. Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan)

We present the Suzaku spectroscopic study of the Galactic middle-aged supernova remnant (SNR) IC 443. The X-ray spectrum in the 1.75-6.0 keV band is described by an optically thin thermal plasma with the electron temperature of approx0.6 keV and several additional Lyman lines. We robustly detect, for the first time, strong radiative recombination continua (RRC) of H-like Si and S around at 2.7 and 3.5 keV. The ionization temperatures of Si and S determined from the intensity ratios of the RRC to He-like Kalpha lines are approx1.0 keV and approx1.2 keV, respectively. We thus find firm evidence for an extremely overionized (recombining) plasma. As the origin of the overionization, a thermal conduction scenario argued in previous work is not favored in our new results. We propose that the highly ionized gas was made at the initial phase of the SNR evolution in dense regions around a massive progenitor, and the low electron temperature is due to a rapid cooling by an adiabatic expansion.

• OSTI ID: 21378427
• Journal Information: Astrophysical Journal (Online), Journal Name: Astrophysical Journal (Online) Journal Issue: 1 Vol. 705; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELECTRON TEMPERATURE
ENERGY RANGE
ENERGY TRANSFER
HEAT TRANSFER
IONIZATION
IONIZING RADIATIONS
KEV RANGE
KEV RANGE 01-10
LYMAN LINES
PLASMA
RADIATIONS
RECOMBINATION
SPECTRA
SUPERNOVA REMNANTS
THERMAL CONDUCTION
X RADIATION
X-RAY SPECTRA