| タイトル | When a Standard Candle Flickers: Crab Nebula Variations in Hard X-rays |
| 本文（外部サイト） | http://hdl.handle.net/2060/20120014194 |
| 著者（英） | Gehrels, N.; Krimm, H. A.; Greiner, J.; Bhat, P. N.; Case, G. L.; Kouveliotou, C.; Cherry, M. L.; Connaughton, V.; Briggs, M. S.; Jenke, P.; Finger, M. H.; Meegan, C. A.; Jahoda, K.; Lund, N.; Natalucci, L.; Kuulkers, E.; Rodi, J. C.; Camero-Arranz, A.; Chaplin, V.; Kippen, R. M.; Wilson-Hodge, Collen A.; Baumgartner, W. H.; Beklen, E.; Paciesas, W. S.; Preece, R. |
| 著者所属（英） | NASA Marshall Space Flight Center |
| 発行日 | 2012-03-29 |
| 言語 | eng |
| 内容記述 | RXTE played a crucial role in our surprising discovery that the Crab Nebula is variable in hard X-rays. In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM), August 2008-2010, a approx.7% (70 mcrab) decline was discovered in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline was independently confirmed in the ~15-50 keV band with four other instruments: the RXTE/PCA, Swift/BAT, INTEGRAL/IBIS, and INTEGRAL/SPI. The pulsed flux measured with RXTE/PCA from 1999-2010 was consistent with the pulsar spin-down, indicating that the observed changes were nebular. From 2001 to 2010, the Crab nebula flux measured with RXTE/PCA was particularly variable, changing by up to approx.3.5% per year in the 15-50 keV band. These variations were confirmed with INTEGRAL/SPI starting in 2003 and Swift/BAT starting in 2005. Before 2001 and since 2010, the Crab nebula 15-50 keV flux measured with RXTE/PCA appeared more stable, varying by less than 2% per year. In this talk I will present Crab light curves including RXTE data for the entire 16-year mission in multiple energy bands. |
| NASA分類 | Astrophysics |
| レポートNO | M12-1577 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
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