TeV Gamma-Ray Emission from Vela X: Leptonic or Hadronic?

Abstract

We study nonthermal photon emission properties from Vela X in both a leptonic and a hadronic-leptonic model. In the leptonic model, it is difficult to reproduce the observed photon spectrum from X-ray to TeV bands using reasonable model parameters; the model results can compare with either the observed data at the TeV band (the total energy of electrons required to match the observations is W _e ≈ 6.1 × 10⁴⁵ erg) or those at the X-ray band (W _e ≈ 1.3 × 10⁴⁵ erg). In the hadronic-leptonic model, however, the observed photon spectrum can be reproduced in the hadronic-leptonic model and TeV photons are mainly from π⁰ decay in proton-proton interaction. The energy required for iron nuclei released in the pulsar wind is W _Fe ≈ 2.1 × 10⁴⁸ erg and the energy of iron nuclei transferred to positrons is W_e^+≈ 8.4× 10^{45} erg in this case.