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When a standard candle flickers: crab nebula variations in hard x-rays (Document No: 20120001447)
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Beklen, E. Kouveliotou, C. Wilson-Hodge, Colleen A. Connaughton, V. Krimm, H. A. Finger, M. H. Meegan, C. A. Jahoda, K. Preece, R. Cherry, M. L. Jenke, P. Bhat, P. N. Camero-Arranz, A. Kuulkers, E. Baumgartner, W. H. Briggs, M. S. Paciesas, W. S. Lund, N. Rodi, J. C. Case, G. L. Chaplin, V. Greiner, J. Natalucci, L. Kippen, R. M. Gehrels, N. |
| Copyright Year | 2011 |
| Description | In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM) since August 2008, a ~7% (70 mcrab) decline was observed in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline is independently confirmed in the ~15-50 keV band with four other instruments: Swift/BAT, the RXTE/PCA, INTEGRAL/IBIS, and INTEGRAL/SPI. A similar decline is also observed in the ~3-15 keV data from the RXTE/PCA and in the 50-100 keV band with GBM, Swift/BAT, INTEGRAL/IBIS, and INTEGRAL/SPI. The pulsed flux measured with RXTE/PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a ~3 year timescale are also seen independently with the PCA, BAT, IBIS, and SPI from 2005 to 2008, with a flux minimum in April 2007. As of April 2011, the Crab nebula flux has stopped declining and may be beginning to increase. We will present updated results on our multi-instrument study of long-term Crab nebula variations. |
| File Size | 8468 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20120001447 |
| Archival Resource Key | ark:/13960/t26b24c7c |
| Language | English |
| Publisher Date | 2011-09-07 |
| Access Restriction | Open |
| Subject Keyword | Astronomy Variations X Ray Timing Explorer Occultation Crab Nebula Gamma Ray Bursts Pulsars Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
