Associations of very high energy gamma-ray sources discovered by H.E.S.S. with pulsar wind nebulae

Abstract

The H.E.S.S. array of imaging Cherenkov telescopes has discovered a number of previously unknown γ-ray sources in the very high energy (VHE) domain above 100 GeV. The good angular resolution of H.E.S.S. (∼ 0.1 • per event), as well as its sensitivity (a few percent of the Crab Nebula flux) and wide 5 • field of view, allow a much better constrained search for counterparts in comparison to previous instruments. In several cases, the association of the VHE sources revealed by H.E.S.S. with pulsar wind nebulae (PWNe) is supported by a combination of positional and morphological evidence, multi-wavelength observations, and plausible PWN model parameters. These include the plerions in the composite supernova remnants G 0.9+0.1 and MSH 15-52, the recently discovered Vela X nebula, two new sources in the Kookaburra complex, and the association of HESS J1825-137 with PSR B1823-13. The properties of these better-established associations are reviewed. A number of other sources discovered by H.E.S.S. are located near high spin-down power pulsars, but the evidence for association is less complete. These possible associations are also discussed, in the context of the available multi-wavelength data and plausible PWN scenarios.

The Field of the TeV Source HESS J1804−216 in X‐Rays and Other Wavelengths

“…To date, young Vela-like pulsars have been found in the vicinity of $10 extended TeV sources (e.g., de Jager 2006; Gallant et al 2006). Since both pulsars and TeV sources are concentrated in the Galactic plane, and the extended TeV sources have typical sizes of $5 0 Y15 0 , one could attempt to explain this by a chance coincidence.…”

Modulations in Spectra of Galactic Gamma-ray sources as a result of photon-ALPs mixing.

“…PSR J1648-4611 is a very-high-energy (VHE) γ − ray source obverved by HESS [12] as well as Fermi LAT, which is is centered on the massive stellar cluster Westerlund 1. PSR J1718-3825 and PSR J1702-4182 has been discovered associated wth the pulsar wind nebula candidate: HESS J1718-385 [13] and HESS J1702-420 [14] with a spin-down age of 55 kyr respectively in 2006 . All of these bright six pulsars have low galactic latitude so that the emitted photons can directly penetrate into the Galactic spiral arms (see Fig.…”

VHE Gamma-ray supernova remnants

“…GLAST will shed more light on this population and possibly establish PWN as emitters in the MeV to GeV range. In VHE γ-rays PWN make up the majority of the identified Galactic sources detected so far Gallant, 2006). Apart from the Crab Nebula (the brightest steady VHE γ-ray source) several prominent PWN were identified in VHE γ-rays in the last two years.…”