Probing the radio to X-ray connection of the Vela X PWN with Fermi LAT and H.E.S.S

Abstract

Morphologically it appears as if the Vela X PWN consists of two emission regions: whereas X-ray (1 keV) and very high energy (VHE) H.E.S.S. gamma-ray observations appear to define a cocoon type shape south of the pulsar, radio observations reveal an extended area of size 2 deg by 3 deg (including the cocoon area), also south of the Vela pulsar. Since no wide field of view (FoV) observations of the synchrotron emission between radio and X-rays are available, we do not know how the lepton (e+/-) spectra of these two components connect and how the morphology changes with energy. Currently we find that two distinct lepton spectra describe the respective radio and X-ray/VHE gamma-ray spectra, with a field strength of 5 muG self-consistently describing a radiation spectral break (or energy maximum) in the multi-TeV domain as observed by H.E.S.S. (if interpreted as IC radiation), while predicting the total hard X-ray flux above 20 keV (measured by the wide FoV INTEGRAL instrument) within a factor of two. If this same field strength is also representative of the radio structure (including filaments), the implied IC component corresponding to the highest radio frequencies should reveal a relatively bright high energy gamma-ray structure and Fermi LAT should be able to resolve it. A higher field strength in the filaments would however imply fewer leptons in Vela X and hence a fainter Fermi LAT signal.

Accepted for publication in Astrophysical Journal Letters, 11 pages, 1 figure

References in corpus (4)

• First detection of a VHE gamma-ray spectral maximum from a Cosmic source: H.E.S.S. discovery of the Vela X nebula
• Two decades of pulsar timing of Vela
• Probing the Nature of the Vela X Cocoon
• Estimating the birth period of pulsars through GLAST/LAT observations of their wind nebulae

Cited by in corpus (8)

• Probing the Nature of the Vela X Cocoon
• The imprint of pulsar parameters on the morphology of Pulsar Wind Nebulae
• H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula
• Perspective on the cosmic-ray electron spectrum above TeV
• A detailed look at the thermal and non-thermal X-ray emission from the Vela supernova remnant with SRG/eROSITA
• On the Gamma-Ray Nebula of Vela Pulsar. I. Very Slow Diffusion of Energetic Electrons within the TeV Nebula
• The Vela pulsar and its pulsar wind nebula Vela-X using 13 years of Fermi-LAT Observations
• Circular Polarization of Pulsar Wind Nebulae and the Cosmic-Ray Positron Excess