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R.E. Rothschild (CASS/UCSD), J. Wilms (U of Warwick), S. Benlloch, R. Staubert (IAAT), W. Collmar (MPE), G.M. Madejski (Stanford), H. Khandrika (LJHS)
Three simultaneous observations of the radio galaxy Centaurus A by RXTE and INTEGRAL were performed in 2003 and 2004 as part of the INTEGRAL AO-1. The data reveal a factor of 2 decrease in the Cen A 2-10 keV flux between the first and second observations separated by 10 months, and a ~20% increase between the second and third observations separated by 5 weeks. The power law index seen by both missions varied little (gamma~1.8) as did the iron line flux. No evidence of a break in the power law was detected to 200 keV. The RXTE instruments (PCA and HEXTE) and the INTEGRAL instruments (ISGRI and SPI) agreed well on the spectral index, albeit with the known residuals in ISGRI. PCA, HEXTE, and SPI normalizations were within 10% of each other while the ISGRI normalization was ~65% of the PCA normalization. A discussion of the consequences of the variability will be given. This research is supported by NASA contract NAG5-30720 and grant NAG5-12957.
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.