Papers

Peer-reviewed
Aug, 2009

Super-Hard X-Ray Emission from eta Carinae Observed with Suzaku

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
  • Akiko Sekiguchi
  • ,
  • Masahiro Tsujimoto
  • ,
  • Shunji Kitamoto
  • ,
  • Manabu Ishida
  • ,
  • Kenji Hamaguchi
  • ,
  • Hideyuki Mori
  • ,
  • Yohko Tsuboi

Volume
61
Number
4
First page
629
Last page
637
Language
English
Publishing type
Research paper (scientific journal)
DOI
10.1093/pasj/61.4.629
Publisher
OXFORD UNIV PRESS

We present the Suzaku results of eta Carinae in the 5-50 keV range conducted twice around the apastron in 2005 August for 50 ks and in 2006 February for 20 ks. The X-ray Imaging Spectrometer (XIS) produced hard (5-12 keV) band spectra, resolving K shell lines from highly ionized Fe and Ni. The Hard X-ray Detector yielded a significant detection in the super-hard (15-50 keV) band, which was uncontaminated by near-by sources. We constrained the temperature of the optically thin thermal plasma emission dominant in the hard band to be 3-4 keV using the K-shell line features with the XIS. We found significant excess emission above the thermal emission in the super-hard band with the PIN, confirming the previous INTEGRAL ISGRI report. The entire 5-50 keV spectra were fitted by a combination of a thermal plasma model plus a flat power-law, or a very hot thermal bremsstrahlung model for the excess emission. No significant change of the excess emission was found at different epochs within the systematic and statistical uncertainties, and no flare-like flux amplification was seen in the hard band, indicating that the excess emission is a steady phenomenon. We argue that the super-hard emission is attributable to the inverse Compton of stellar UV photons by non-thermal electrons or to the thermal bremsstrahlung of very hot plasma, and not to the bremsstrahlung by non-thermal electrons colliding with cold ambient matter.

Link information
DOI
https://doi.org/10.1093/pasj/61.4.629
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000271364000007&DestApp=WOS_CPL
ID information
  • DOI : 10.1093/pasj/61.4.629
  • ISSN : 0004-6264
  • eISSN : 2053-051X
  • Web of Science ID : WOS:000271364000007

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