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Register a new userINTEGRAL observations of the PSR B1259-63 / SS2883 system after the 2004 periastron passage
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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.
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Aim. In this paper we present very high energy (VHE; E>100 GeV) data from the gamma-ray binary system PSR B1259-63/LS 2883 taken around its periastron passage (15th of December 2010) with the High Energy Stereoscopic System (H.E.S.S.) of Cherenkov Telescopes. We aim to search for a possible TeV counterpart of the GeV flare detected by the Fermi LAT. In addition, we aim to study the current periastron passage in the context of previous observations taken at similar orbital phases, testing the repetitive behavior of the source. Methods. Observations at VHE were conducted with H.E.S.S. from 9th to 16th of January 2011. The total dataset amounts to around 6 h of observing time. Results. The source is detected in the 2011 data at a significance level of 11.5sigma revealing an averaged integral flux above 1 TeV of (1.01 pm 0.18_{stat} pm 0.20_{sys}) times 10^{-12} cm^{-2}s^{-1}. The differential energy spectrum follows a power-law shape with a spectral index Gamma = 2.92 pm 0.30_{stat} pm 0.20_{sys} and a flux normalisation at 1 TeV of N_{0} = 1.95 pm 0.32_{stat} pm 0.39_{sys}) times 10^{-12} TeV^{-1} cm^{-2} s^{-1}. The measured lightcurve does not show any evidence for variability of the source on the daily scale. Conclusions. The measured integral flux and the spectral shape of the 2011 data are compatible with the results obtained around previous periastron passages. The absence of variability in the H.E.S.S. data indicates that the GeV flare observed by Fermi LAT in the time period covered also by H.E.S.S. observations originates in a different physical scenario than the TeV emission. Additionaly, new results compared to those obtained in the observations which were performed in 2004 at a similar orbital phase, further support the hypothesis of the repetitive behavior of the source.
We report on broad multi-wavelength observations of the 2010-2011 periastron passage of the gamma-ray loud binary system PSR B1259-63. High resolution interferometric radio observations establish extended radio emission trailing the position of the pulsar. Observations with the Fermi Gamma-ray Space Telescope reveal GeV gamma-ray flaring activity of the system, reaching the spin-down luminosity of the pulsar, around 30 days after periastron. There are no clear signatures of variability at radio, X-ray and TeV energies at the time of the GeV flare. Variability around periastron in the H$alpha$ emission line, can be interpreted as the gravitational interaction between the pulsar and the circumstellar disk. The equivalent width of the H$alpha$ grows from a few days before periastron until a few days later, and decreases again between 18 and 46 days after periastron. In near infrared we observe the similar decrease of the equivalent width of Br$gamma$ line between the 40th and 117th day after the periastron. For the idealized disk, the variability of the H$alpha$ line represents the variability of the mass and size of the disk. We discuss possible physical relations between the state of the disk and GeV emission under assumption that GeV flare is directly related to the decrease of the disk size.
PSR B1259-63 is a gamma-ray binary system hosting a radio pulsar orbiting around a O9.5Ve star, LS 2883, with a period of ~3.4 years. The interaction of the pulsar wind with the LS 2883 outflow leads to unpulsed broad band emission in the radio, X-rays, GeV and TeV domains. While the radio, X-ray and TeV light curves show rather similar behaviour, the GeV light curve appears very different with a huge outburst about a month after a periastron. The energy release during this outburst seems to significantly exceed the spin down luminosity of the pulsar and the GeV light curve and energy release varies from one orbit to the next. In this paper we present for the first time the results of optical observations of the system in 2017, and also reanalyze the available X-ray and GeV data. We present a new model in which the GeV data are explained as a combination of the bremsstrahlung and inverse Compton emission from the unshocked and weakly shocked electrons of the pulsar wind. The X-ray and TeV emission is produced by synchrotron and inverse Compton emission of energetic electrons accelerated on a strong shock arising due to stellar/pulsar winds collision. The brightness of the GeV flare is explained in our model as a beaming effect of the energy released in a cone oriented, during the time of flare, in the direction of the observer.
The binary system PSR B1259-63/LS 2883 is well sampled in radio, X-rays, and TeV gamma-rays, and shows orbital phase-dependent variability in these frequencies. The first detection of GeV gamma-rays from the system was made around the 2010 periastron passage. In this Letter, we present an analysis of X-ray and gamma-ray data obtained by the Swift/XRT, NuSTAR/FPM, and Fermi/LAT, through the recent periastron passage which occurred on 2014 May 4. While PSR B1259-63/LS 2883 was not detected by the LAT before and during this passage, we show that the GeV flares occurred at a similar orbital phase as in early 2011, thus establishing the repetitive nature of the post-periastron GeV flares. Multiple flares each lasting for a few days have been observed and short-term variability is seen as well. We also found X-ray flux variation contemporaneous with the GeV flare for the first time. A strong evidence of the keV-to-GeV connection came from the broadband high-energy spectra, which we interpret as synchrotron radiation from the shocked pulsar wind.
PSR B1259-63/LS 2883 is a gamma-ray binary system containing a radio pulsar in a highly elliptical ~3.4-year orbit around a Be star. In its 2010 periastron passage, multiwavelength emission from radio to TeV was observed, as well as an unexpected GeV flare measured by the Fermi Large Area Telescope (LAT). Here, we report the results of LAT monitoring of PSR B1259-63 during its most recent 2014 periastron passage. We compare the gamma-ray behavior in this periastron with the former in 2010 and find that PSR B1259-63 shows a recurrent GeV flare. The similarities and differences in the phenomenology of both periastron passages are discussed.
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