Modeling high-energy light curves of the PSR B1259-63/LS 2883 binary based on 3-D SPH simulations

TL;DR

This study uses 3-D SPH simulations to model the high-energy light curves of PSR B1259-63/LS 2883, reproducing observed X-ray features and exploring the effects of pulsar-disk interactions on gamma-ray emissions.

Contribution

The paper presents a novel 3-D SPH simulation approach to model the high-energy emissions of the binary system, linking shock geometry to observed light curves.

Findings

Reproduced the double-peaked X-ray light curve under dense Be disk conditions.

Identified the causes of pre- and post-periastron peaks as changes in shock acceleration efficiency.

Discussed the impact of cooling processes on TeV gamma-ray light curves.

Abstract

Temporal changes of X-ray to very-high-energy gamma-ray emissions from the pulsar-Be star binary PSR B1259-63/LS 2883 are studied based on 3-D SPH 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 model TeV light curve, which also shows a double peak feature, the first peak appears around the periastron phase. The possible effects of cooling processes on the TeV light curve are briefly discussed.