TeV flux modulation in PSR B1259−63/LS2883

Department of Physics, Humboldt University, Newtonstrasse 15, Berlin, 12489, Germany
e-mail: mkersch@physik.hu-berlin.de

Received: 1 March 2010
Accepted: 3 September 2010

Abstract

Context. PSR B1259−63/LS2883  is a binary system where a 48 ms pulsar orbits a massive Be star with a highly eccentric orbit (e = 0.87) with a period of 3.4 years. The system exhibits variable, non-thermal radiation visible from radio to very high energies (VHE) around periastron passage. This radiation is thought to come from particles accelerated in the shock region between the pulsar wind (PW) and stellar outflows.

Aims. The consistency of the HESS  data with the inverse Compton (IC) scenario is studied in the context of dominant orbital-phase-dependent adiabatic losses, and the dependence of the observed TeV flux with the separation distance analysed.

Methods. Model calculations based on IC scattering of shock accelerated PW electrons and UV photons are performed. Different non-radiative cooling profiles are suggested for the primary particle population to account for the variable TeV flux.

Results. The TeV fluxes obtained with HESS in the years 2004 and 2007 only seem to depend on the binary separation. The results hint at a peculiar non-radiative cooling profile around periastron dominating the VHE emission in PSR B1259−63. The location of the stellar disc derived from this non-radiative cooling profile is in good agreement with what is inferred from radio observations.