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When a standard candle flickers: hard x-ray variations in the crab nebula (Document No: 20150002961)
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Markwardt, Craig Greiner, Jochen Cherry, Michael L. Madsen, Kristin Case, Gary L. Buehler, Rolf Connaughton, Valerie Finger, Mark H. Jahoda, Keith Beklen, Elif Jenke, Peter Hays, Elizabeth A. Meegan, Charles A. Kouveliotou, Chryssa Gehrels, Neil Harrison, Fiona Baumgartner, Wayne H. Diehl, Roland Kuulkers, Erik Kippen, R. M. Briggs, Michael S. Camero-Arranz, Ascension Bhat, Narayana P. Krimm, Hans A. Wilson-Hodge, Colleen |
| Copyright Year | 2014 |
| Description | In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM), August 2008 to August 2010, an approximately 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 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 approximately3.5% per year in the 15-50 keV band. These variations were confirmed with INTEGRAL/SPI starting in 2003, Swift/BAT starting in 2005, and Fermi GBM starting in 2008. Before 2001 and since 2010, the Crab nebula flux has appeared more stable, varying by less than 2% per year. At higher energies, above 50 keV, the Crab flux appears to be slowly recovering to its 2008 levels. I will present updated light curves in multiple energy bands for the Crab nebula, including recent data from Fermi GBM, Swift/BAT, INTEGRAL, MAXI, and NuSTAR and a 16-year long light curve from RXTE/PCA. We will compare these variations to higher energies as well, e.g. Fermi LAT. |
| File Size | 86606 |
| Page Count | 2 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150002961 |
| Archival Resource Key | ark:/13960/t47q40c6n |
| Language | English |
| Publisher Date | 2014-09-30 |
| Access Restriction | Open |
| Subject Keyword | Astrophysics Space Radiation Energy Bands Crab Nebula Pulsars Flux Light Curve Gamma Ray Bursts Fermi Gamma-ray Space Telescope Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
