Extended hard X-ray emission from the Vela pulsar wind nebula

Abstract

The nebula powered by the Vela pulsar is one of the best examples of an evolved pulsar wind nebula, allowing to access 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 towards 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 point spread function, supporting the hypothesis of a nebula more diffuse than previously thought. A break at ~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 by electrons injected in the last ~2000 years. Broad-band modeling also implies a magnetic field higher than 10 microGauss 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.

arXiv comment15 pages, 4 figures, accepted for publication in ApJ Letters

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Cited by in corpus (8)

• Pulsar-Wind Nebulae: Recent Progress in Observations and Theory
• Pulsar wind nebulae with bow shocks: non-thermal radiation and cosmic ray leptons
• Probing the extent of the non-thermal emission from the Vela X region at TeV energies with H.E.S.S
• Pulsar Wind Nebulae Created by Fast-Moving Pulsars
• Pulsar-wind nebulae and magnetar outflows: observations at radio, X-ray, and gamma-ray wavelengths
• H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula
• A detailed look at the thermal and non-thermal X-ray emission from the Vela supernova remnant with SRG/eROSITA
• INTEGRAL View of TeV Sources: A Legacy for the CTA Project