Modeling high-energy light curves of the PSRB1259-63/LS 2883 binary based on 3D SPH simulations

Abstract

Temporal changes of X-ray to very high energy gamma-ray emissions from the pulsar-Be-star binary PSRB1259-63/LS 2883 are studied based on three-dimensional smoothed particle hydrodynamic simulations of pulsar wind interaction with Be-disk and wind. We focus on the periastron passage of the binary and calculate the variation of the synchrotron and inverse-Compton emissions using the simulated shock geometry and pressure distribution of the pulsar wind. The characteristic double-peaked X-ray light curve from observations is reproduced by our simulation under a dense Be-disk condition (base density ∼10 -9 g cm-3). We interpret the pre- and post-periastron peaks as being due to a significant increase in the conversion efficiency from pulsar spin-down power to the shock-accelerated particle energy at orbital phases when the pulsar crosses the disk before periastron passage, and when the pulsar wind creates a cavity in the disk gas after periastron passage, respectively. On the contrary, in the modelTeV light curve, which also shows a double-peak feature, the first peak appears around the periastron phase. The possible effects of cooling processes on theTeV light curve are briefly discussed. © 2012. The American Astronomical Society. All rights reserved.