The 2009 Fermi Symposium

H.E.S.S. TeV Gamma-ray Sources Associated with Pulsar Wind Nebulae

Christoph Deil

Abstract:

In the last five years, the H.E.S.S. system of Cherenkov telescopes has surveyed the Galactic plane at TeV energies with unprecedented sensitivity and detected ~50 Galactic sources. While for many of these the firm identification with objects at other wavelengths is difficult, pulsar wind nebulae (PWNe) have been identified as one, possibly the largest, source class. The TeV emission from PWNe is usually interpreted as inverse Compton emission from relativistic electrons and positrons accelerated in the pulsar magnetosphere, and probably accelerated further at the termination shock of the pulsar wind. Details of the pulsar-wind-nebula connections are still poorly understood, but can be probed by multi-wavelength observations from radio to gamma rays. Here we present an overview of the TeV PWN source population as seen by H.E.S.S. in the Galactic plane survey and discuss the multi-wavelength context. The recent Fermi detection of many gamma-ray only pulsars leads to a more complete sample of young and energetic pulsars and will eventually make it possible to identify some of the currently unidentified TeV sources as PWNe. The measurement or upper limit of the inverse Compton flux of the nebula at GeV energies by Fermi and at TeV energies by H.E.S.S., in combination with radio and X-ray measurements of the synchrotron emission, makes it possible to infer physical properties of the nebula through modeling of its broad-band spectral energy distribution.