EXTENDED HARD X-RAY EMISSION FROM THE VELA PULSAR WIND NEBULA
- Francois Arago Centre, APC (UMR 7164 Universite Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris), 13 rue Watt, F-75205 Paris Cedex 13 (France)
- AIM (UMR 7158 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d'Astrophysique, F-91191 Gif-sur-Yvette (France)
- Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France)
- Faculty of Physical and Applied Science, University of Southampton, Southampton, SO17 1BJ (United Kingdom)
- International Space Science Institute (ISSI), Hallerstrasse 6, CH-3012 Bern (Switzerland)
- Laboratoire Univers et Particules de Montpellier (LUPM), Universite Montpellier II, CNRS/IN2P3 UMR 5299, F-34095 Montpellier (France)
The nebula powered by the Vela pulsar is one of the best examples of an evolved pulsar wind nebula, allowing access to the particle injection history and the interaction with the supernova ejecta. We report on the INTEGRAL discovery of extended emission above 18 keV from the Vela nebula. The northern side has no known counterparts and it appears larger and more significant than the southern one, which is in turn partially coincident with the cocoon, the soft X-ray, and TeV filament toward the center of the remnant. We also present the spectrum of the Vela nebula in the 18-400 keV energy range as measured by IBIS/ISGRI and SPI on board the INTEGRAL satellite. The apparent discrepancy between IBIS/ISGRI, SPI, and previous measurements is understood in terms of the point-spread function, supporting the hypothesis of a nebula more diffuse than previously thought. A break at {approx}25 keV is found in the spectrum within 6' from the pulsar after including the Suzaku XIS data. Interpreted as a cooling break, this points out that the inner nebula is composed of electrons injected in the last {approx}2000 years. Broadband modeling also implies a magnetic field higher than 10 {mu}G in this region. Finally, we discuss the nature of the northern emission, which might be due to fresh particles injected after the passage of the reverse shock.
- OSTI ID:
- 22047303
- Journal Information:
- Astrophysical Journal Letters, Vol. 743, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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