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Register a new userA Search for TeV Gamma-ray Emission from the PSR B1259-63/SS2883 Binary System with the CANGAROO-II 10-m Telescope
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Observations of the PSR B1259-63/SS2883 binary system using the CANGAROO-II Cherenkov telescope are reported. This nearby binary consists of a 48msec 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 October 2000 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 gamma-ray 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, the mass-outflow parameters of the Be star are constrained.
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We examine changes of the $gamma$-ray intensity observed from the direction of the binary system PSR B1259-63/LS 2883 during campaigns around its three periastron passages. A simple and straightforward method is applied to the published data obtained with the Imaging Atmospheric Cherenkov Technique. Regardless of many issues of the detection process, the method works only with numbers of very high energetic photons registered in the specified regions. Within the realm of this scheme, we recognized changes attributable to the variations of the intrinsic source activity at high levels of significance.
PSR B1259-63/LS 2883 is a very high energy (VHE; E > 100 GeV) gamma-ray emitting binary consisting of a 48 ms pulsar orbiting around a Be star with a period of 3.4 years. The Be star features a circumstellar disk which is inclined with respect to the orbit in such a way that the pulsar crosses it twice every orbit. The circumstellar disk provides an additional field of target photons which may contribute to inverse Compton scattering and gamma-gamma absorption, leaving a characteristic imprint in the observed spectrum and light curve of the high energy emission. We study the signatures of Compton-supported, VHE gamma-ray induced pair cascades in the circumstellar disc of the Be star and their possible contribution to the GeV flux. We also study a possible impact of the gamma-gamma absorption in the disk on the observed TeV light curve. We show that the cumulative absorption of VHE gamma-rays in stellar and disk photon fields can explain the modulation of the flux at the periastron passage.
The millisecond pulsar PSR B1259-63 and the Be star SS2883 are situated in a highly eccentric binary system, with orbital period ~3.4 years. We report on hard X-ray observations obtained with the INTEGRAL satellite close to the 2004 periastron passage. These are the first imaging observations of this system in the hard X-ray range (>20 keV) and allow the emission of PSR B1259-63 to be separated from that of a nearby unidentified variable source which may have contaminated previous hard X-ray observations of this system. Using the IBIS/ISGRI instrument we measured a flux of ~2--6 mCrab in the 20--200 keV range, with a power law spectrum of photon index of 1.3 +/- 0.5.
Observing the famous high-mass, eccentric X-ray and gamma-ray binary PSR B1259-63/LS 2883 with Chandra, we detected X-ray emitting clumps moving from the binary with speeds of about 0.1 of the speed of light, possibly with acceleration. The clumps are being ejected at least once per binary period, 3.4 years, presumably around binary periastrons. The power-law spectra of the clumps can be interpreted as synchrotron emission of relativistic electrons. Here we report the results of 8 observations of the clumps in 2011-2017 (two binary cycles) and discuss possible interpretations of this unique phenomenon.
A preliminary result from Markarian 421 observations in the energy region above 10 TeV with the CANGAROO-II 10 m telescope is presented. In January 2001, the HEGRA group reported that Markarian 421 had become very active, with flux levels up to 4 times that of the Crab Nebula. As a result, we observed Mkn 421 during six nights from January 24th to February 1st, and four nights from March 1st to 4th. Observations were carried out using the very large zenith angle technique ($sim$70 degree) and the energy threshold is estimated from Monte Carlo simulations to be around 10 TeV. We have detected gamma-ray emission in this energy range.
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