A Search for TeV Gamma‐Ray Emission from the PSR B1259−63/SS 2883 Binary System with the CANGAROO‐II 10 Meter Telescope

Abstract

Observations of the PSR B1259À63/SS 2883 binary system using the CANGAROO-II Cerenkov telescope are reported. This nearby binary consists of a 48 ms radio pulsar in a highly eccentric orbit around a Be star and offers a unique laboratory to investigate the interactions between the outflows of the pulsar and Be star at various distances. It has been pointed out that the relativistic pulsar wind and the dense mass outflow of the Be star may result in the emission of gamma rays up to TeV energies. We have observed the binary in 2000 and 2001, $47 and $157 days after the 2000 October periastron. Upper limits at the 0.13-0.54 crab level are obtained. A new model calculation for high-energy gamma-ray emission from the Be star outflow is introduced, and the estimated gammaray flux, considering bremsstrahlung, inverse Compton scattering, and the decay of neutral pions produced in proton-proton interactions, is found to be comparable to the upper limits of these observations. Comparing our results with these model calculations, we constrain the mass-outflow parameters of the Be star.

INTEGRAL observations of the PSR B1259-63/SS2883 system after the 2004 periastron passage

“…For the source of the TeV emission, Kirk et al (1999) propose relativistic electrons from the pulsar wind, while Kawachi et al (2004) favour interactions of protons accelerated in a shock wave during the passage of the neutron star through the Be-star disk. As the hard X-ray and TeV emission may originate from different populations of particles, TeV observations alone may be unable to constrain γ w and the post-periastron data reported here also leaves this question open.…”

Modeling High-Energy Light Curves of the PSR B1259–63/Ls 2883 Binary Based on 3d SPH Simulations

“…The non-thermal emission mechanisms of the system have been studied in the framework of leptonic (e.g., Tavani & Arons 1997;Khangulyan et al 2007;Sierpowska-Bartosik & Bednarek 2008;Takata & Taam 2009;Dubus et al 2010) and hadronic models (Kawachi et al 2004; see also Neronov & Chernyakova 2007). Unfortunately, Be-disk models which have been adopted so far in this field of research are mostly outdated, and are significantly different from the model being widely accepted by the Be star research community currently, i.e., the viscous decretion disk model (Lee et al 1991;see also Porter 1999 andCarciofi &Bjorkman 2006).…”

High Energy Emissions from the PSR1259-63/SS2883 Binary System

“…The binary system was observed with the CANGAROO-II Cherenkov telescope at two different orbital phases; for several days in December 2000 and in March 2001, about 47 and 157 days after the periastron of October 2000 [11]. They have no data closer to periastron as observing conditions were not favorable during June-November 2000.…”

“…A new model of gamma-ray emissivity is introduced, considering the particles accelerated in the Be star outflow [11]. Figure 1 schematically illustrates the assumed configuration of the system: the pulsar and its relativistic pulsar wind, the Be star and its polar and disc-like outflows.…”

“…The CANGAROO observational upper limits [11] are compared with light curves calculated with the model assumption (i) in the disc-pulsar wind interaction. The spectra are integrated (E ≥ 1 TeV) for n =2.5, v 0 = 10 6 cms −1 , and for four different mass outflow parameters, x disc = 500, 1000, 1500, and 5000 (Fig.…”