MODELING HIGH-ENERGY LIGHT CURVES OF THE PSR B1259–63/LS 2883 BINARY BASED ON 3D SPH SIMULATIONS

Abstract

Temporal changes of X-ray to very-high-energy gamma-ray emissions from the\npulsar-Be star binary PSR B1259-63/LS 2883 are studied based on 3-D SPH\nsimulations of pulsar wind interaction with Be-disk and wind. We focus on the\nperiastron passage of the binary and calculate the variation of the synchrotron\nand inverse-Compton emissions using the simulated shock geometry and pressure\ndistribution of the pulsar wind. The characteristic double-peaked X-ray light\ncurve from observations is reproduced by our simulation under a dense Be disk\ncondition (base density ~10^{-9} g cm^{-3}). We interpret the pre- and\npost-periastron peaks as being due to a significant increase in the conversion\nefficiency from pulsar spin down power to the shock-accelerated particle energy\nat orbital phases when the pulsar crosses the disk before periastron passage,\nand when the pulsar wind creates a cavity in the disk gas after periastron\npassage, respectively. On the contrary, in the model TeV light curve, which\nalso shows a double peak feature, the first peak appears around the periastron\nphase. The possible effects of cooling processes on the TeV light curve are\nbriefly discussed.\n