SUZAKU DISCOVERY OF THE STRONG RADIATIVE RECOMBINATION CONTINUUM OF IRON FROM THE SUPERNOVA REMNANT W49B

Journal Article · Fri Nov 20 00:00:00 EST 2009 · Astrophysical Journal (Online)

DOI:https://doi.org/10.1088/0004-637X/706/1/L71· OSTI ID:21378205

Ozawa, M; Koyama, K ^[1]; Yamaguchi, H; Tamagawa, T ^[2]; Masai, K ^[3]

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1. Department of Physics, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)
2. RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
3. Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan)

We present a hard X-ray spectrum of unprecedented quality of the Galactic supernova remnant (SNR) W49B obtained with the Suzaku satellite. The spectrum exhibits an unusual structure consisting of a saw-edged bump above 8 keV. This bump cannot be explained by any combination of high-temperature plasmas in ionization equilibrium. We firmly conclude that this bump is caused by the strong radiative recombination continuum (RRC) of iron, detected for the first time in a SNR. The electron temperature derived from the bremsstrahlung continuum shape and the slope of the RRC is approx1.5 keV. On the other hand, the ionization temperature derived from the observed intensity ratios between the RRC and Kalpha lines of iron is approx2.7 keV. These results indicate that the plasma is in a highly overionized state. Volume emission measures independently determined from the fluxes of the thermal and RRC components are consistent with each other, suggesting the same origin of these components.

• OSTI ID: 21378205
• Journal Information: Astrophysical Journal (Online), Vol. 706, Issue 1; Other Information: DOI: 10.1088/0004-637X/706/1/L71; ISSN 1538-4357
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BREMSSTRAHLUNG
ELECTRON TEMPERATURE
EMISSION
HARD X RADIATION
HOT PLASMA
IONIZATION
IRON
KEV RANGE
RECOMBINATION
SATELLITES
SPECTRA
SUPERNOVA REMNANTS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY RANGE
IONIZING RADIATIONS
METALS
PLASMA
RADIATIONS
TRANSITION ELEMENTS
X RADIATION