PSR J2032+4127 is a gamma-ray and radio-emitting pulsar which has been regarded as a young luminous isolated neutron star. However, its recent spin-down rate has extraordinarily increased by a factor of two. We present evidence that this is due to its motion as a member of a highly-eccentric binary system with a 15-solar-mass Be star, MT91~213. Timing observations show that, not only are the positions of the two stars coincident within 0.4 arcsec, but timing models of binary motion of the pulsar fit the data much better than a model of a young isolated pulsar. MT91~213, and hence the pulsar, lie in the Cyg~OB2 stellar association, which is at a distance of only 1.4-1.7 kpc. The pulsar is currently on the near side of, and accelerating towards, the Be star, with an orbital period of 20-30 years. The next periastron is well-constrained to occur in early 2018, providing an opportunity to observe enhanced high-energy emission as seen in other Be-star binary systems.
LS 2883/PSR B1259-63 is a high mass, eccentric gamma-ray binary that has previously been observed to eject X-ray emitting material. We report the results of recent Chandra observations near binary apastron in which a new X-ray emitting clump of matter was detected. The clump has a high projected velocity of $v_{\perp}\approx 0.07c$ and hard X-ray spectrum, which fits an absorbed power-law model with $Γ=1.1\pm0.3$. Although clumps with similar velocities and spectra were detected in some of the previous binary cycles, no resolved clumps were seen near apastron in the preceding cycle of 2017-202…
We report on high-energy properties of the black widow pulsar PSR J2241$-$5236 in the X-ray and the Fermi-LAT (GeV gamma-ray) bands. In the LAT band, the phase-averaged gamma-ray light curve shows orbital modulation below $\sim$1 GeV with a chance probability ($p$) monotonically decreasing with time to $p\sim 10^{-5}$. The peak of the light curve is near the superior conjunction of the pulsar (binary phase $ϕ_{\rm B}\approx 0.25$). We attribute the modulation to the intra-binary shock (IBS) emission and search for IBS signatures in the archival X-ray data. We find that the X-ray spectral fit r…
We examine changes of the $γ$-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 significanc…
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 ph…
GeV Gamma-ray Emission from the Binary PSR B1259-63/SS2883 During the 2010 Periastron Passage
PSR B1259-63/SS 2883是一个双星系统，由一颗48-ms射电脉冲星和一颗大质量恒星组成，在一个高偏心轨道上运行，周期约为3.4年。据报道，这颗双星的非脉冲和非热辐射在射电、X射线和TeV伽马射线能量范围内。射电和X射线波段的光变曲线显示出典型的双峰特征，这可能是脉冲星穿越过程中脉冲星风和Be盘相互作用的结果。在2004年和2007年的观测中，近星点附近的TeV光变曲线有所不同，这一特征并不确定。我们报告了2010年12月费米-LAT探测到的GeV伽马射线辐射。
Long expected transition states between the rotation powered and accretion powered non-thermal emission in the millisecond pulsar binary systems have been recently observed in the case of three objects PSR J1023+0038, PSR J1824-2452, and PSR J1227-4859. Surprisingly, the transition is related to the significant change in the $γ$-ray flux being a factor of a few higher with the presence of an accretion disk. The origin of this enhanced emission seems to be related to the penetration of the inner pulsar magnetosphere by the accretion disk. We propose that the radiation processes, characteristic …
We present the analysis of the Chandra X-ray Observatory observations of the eccentric gamma-ray binary PSR B1259-63/LS 2883. The analysis shows that the extended X-ray feature seen in previous observations is still moving away from the binary with an average projected velocity of about 0.07c and shows a hint of acceleration. The spectrum of the feature appears to be hard (photon index of 0.8) with no sign of softening compared to previously measured values. We interpret it as a clump of plasma ejected from the binary through the interaction of the pulsar with the decretion disk of the O-star …
We have presented the first joint {\it XMM-Newton} and {\it NuSTAR} analysis of the millisecond pulsar (MSP) binary PSR J1653$-$0158. The 75-minute orbital period inferred from optical and gamma-ray observations together with the 1.97-ms pulsation in the gamma-rays indicate that this system is the most compact Black Widow MSP system known to date. The orbital period was not detected in the {\it XMM-Newton} and {\it NuSTAR} data, probably due to insufficient photon counts obtained in the observations. Fitting the joint X-ray spectrum of PSR J1653$-$0158 with a power law gives a photon index $Γ=…
The energetic pulsar, PSR J2032+4127, has been recently discovered in the direction of the unidentified HEGRA TeV gamma-ray source (TeV J2032+4130). It is proposed that this pulsar forms a binary system with the Be type star, MT91 213, expected to reach the periastron late in 2017. We performed detailed calculations of the gamma-ray emission produced close to the binary system's periastron passage by applying a simple geometrical model. Electrons accelerated at the collision region of pulsar and stellar winds initiate anisotropic Inverse Compton electron-positron pair cascades by scattering so…
We report on X-ray and TeV gamma-ray observations of the pulsar/Be star binary PSR J2032+4127/MT91 213. PSR J2032+4127 is a 143-ms gamma-ray pulsar which shares a long period (45-50 year) and highly eccentric orbit with the massive Be star MT91 213. TeV gamma-ray emission was detected from the binary following a coordinated observing campaign over the fall 2017 periastron with VERITAS, MAGIC, and X-ray monitoring with Swift-XRT. The discovery of this gamma-ray binary makes it just the second such source known to contain a pulsar as the compact object. We report on over 100 hours of extensive T…
PSR J2032+4127 is a young and rapidly rotating pulsar on a highly eccentric orbit around the high-mass Be star MT91 213. X-ray monitoring of the binary system over a $\sim$4000 day period with Swift has revealed an increase of the X-ray luminosity which we attribute to the synchrotron emission of the shocked pulsar wind. We use Swift X-ray observations to infer a clumpy stellar wind with $r^{-2}$ density profile and constrain the Lorentz factor of the pulsar wind to $10^5<γ_w<10^6$. We investigate the effects of an axisymmetric stellar wind with polar gradient on the X-ray emission. Comparison…
XSS J12270-4859 is an X-ray binary associated with the Fermi LAT gamma-ray source 1FGL J1227.9-4852. In 2012 December, this source underwent a transition where the X-ray and optical luminosity dropped and the spectral signatures of an accretion disc disappeared. We report the discovery of a 1.69 millisecond pulsar (MSP), PSR J1227-4853, at a dispersion measure of 43.4 pc cm$^{-3}$ associated with this source, using the GMRT at 607 MHz. This demonstrates that, post-transition, the system hosts an active radio MSP. This is the third system after PSR J1023+0038 and PSR J1824-2452I showing evidenc…
We have performed a series of Chandra X-ray Observatory observations of the gamma-ray binary LS 2883, which is comprised of a young pulsar (PSR B1259-63) orbiting a massive Be star with a period of 1236.7 days. The system was observed in 5 epochs, spanning a range from 352 to 1175 days after the periastron passage on 2014 May 4. The observations confirmed the recurrent nature of the high-speed ejecta that appear as an extended X-ray structure (clump) moving away from the binary. Compared to the results of the previous monitoring campaign (between the 2010 and 2014 periastron passages), this ti…
We report the results from our detailed analysis of the Fermi Large Area Telescope (LAT) data for the pulsar binary PSR B1259-63/LS 2883. During the GeV flares that occurred when the pulsar was in the periastron passages, we have detected a 5--300 GeV component at $\simeq 5σ$ in emission from the binary. The detection verifies the presence of the component that has been marginally found in the previous studies of the binary. Furthermore, we have discovered that this component was present even in the quiescent state of the binary, specifically the mean anomaly phase 0.7--0.9. The component can …
X-ray studies of the Black Widow Pulsar PSR B1957+20
我们报告的黑寡妇脉冲星，PSR B1957+20的钱德拉观测。通过对该脉冲星的深空观测，发现了脉冲星X射线辐射具有二元相位依赖性的证据。二元相分辨光谱分析揭示了PSR B 1957 +20的非热X射线发射，证实了以前的研究结果。这表明X射线主要是由于双星内的冲击发射造成的，当脉冲星风与伴星的烧蚀物质相互作用时，这种冲击发射最强。在我们的研究中确定的几何形状的峰值发射。非热X射线尾谱的边缘软化可能表明在终止激波处注入的粒子主要由同步辐射冷却控制。
We report on the results of the extensive multi-wavelength campaign from optical to GeV gamma-rays of the 2014 periastron passage of PSR B1259-63, which is a unique high-mass gamma-ray emitting binary system with a young pulsar companion. Observations demonstrate the stable nature of the post-periastron GeV flare and prove the coincidence of the flare with the start of rapid decay of the H$α$ equivalent width, usually interpreted as a disruption of the Be stellar disk. Intensive X-ray observations reveal changes in the X-ray spectral behaviour happening at the moment of the GeV flare. We demon…
PSR J2032+4127 has recently been identified as being in a long period (45-50 years) binary in a highly eccentric orbit with the Be star MT91 213. Periastron is due to occur in November 2017 and this rare occurrence has prompted a multiwavelength monitoring campaign to determine if the system is a gamma-ray binary, and, if so, to study what would be only the second gamma-ray binary with a known compact object. In the same direction as TeV J2032+4130, gamma-ray emission from this binary system could be related to the extended very high energy gamma-ray emission from that region. As part of this …
A New Accretion Disk Around the Missing Link Binary System PSR J1023+0038
PSR J1023+0038是一个特殊的系统，用于了解缓慢旋转的中子星如何通过伴星的吸积旋转到毫秒旋转周期。从2007年到2013年作为射电脉冲星观测，光学数据显示该系统在2000/2001年有一个吸积盘。从2013年6月底开始，射电脉冲星已经无法被探测到，这表明它回到了以前的吸积盘状态，在那里系统更像是一个X射线双星。在这封信中，我们报告了有史以来第一次对活跃阶段进行的有针对性的X射线观测，并补充了2013年10月收集的紫外/光学和射电观测。我们找到了强有力的证据，确实是一个吸积盘最近形成的系统中，我们报告的快速X射线变化的检测跨越约两个数量级的光度。在X射线光变曲线的低通量状态或任何其他时间，都没有看到射电脉动。
PSR J0636+5128 is a millisecond pulsar in one of the most compact pulsar binaries known, with a 96\,min orbital period. The pulsar mass function suggests a very low-mass companion, similar to that seen in so-called "black widow" binaries. Unlike in most of those, however, no radio eclipses by material driven off from the companion were seen leading to the possibility that the companion was a degenerate remnant of a carbon-oxygen white dwarf. We report the discovery of the optical counterpart of its companion in images taken with the Gemini North and Keck~I telescopes. The companion varies betw…
The binary of the pulsar PSRB1259$-$63 and the Be star LS 2883 has been observed at the 2010 and 2014 periastron passages in the near-infrared (NIR) bands using the IRSF/SIRIUS and SIRPOL. The light curves in the J-,H-, and Ks-bands are almost identical in these periastron passages. A flare starts no later than 10 days before periastron and the maximum brightening of about 0.1 magnitude is observed 12--17 days after periastron. The rising part of the light curve is steeper and reaches a peak slightly earlier in the Ks-band than in the other bands, thus a characteristic track appears on the NIR…
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 Comp…
PSR J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25-50years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises with a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR~B1259-63/LS2883. It is expected therefore that PSR J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux fr…
We present the discovery of the variable optical and X-ray counterparts to the radio millisecond pulsar (MSP) PSR J1306-40, recently discovered by Keane et al. We find that both the optical and X-ray fluxes are modulated with the same period, which allows us to measure for the first time the orbital period P$_{\rm orb}$=1.09716[6] d. The optical properties are consistent with a main sequence companion with spectral type G to mid K and, together with the X-ray luminosity (8.8$\times$10$^{31}$ erg s$^{-1}$ in the 0.5-10 keV band, for a distance of 1.2 kpc), confirm the redback classification of …
We provide an update on the ongoing monitoring and study of the highly-relativistic double neutron star binary system PSR J1757-1854, a 21.5-ms pulsar in a highly eccentric, 4.4-hour orbit. The extreme nature of this pulsar's orbit allows it to probe a parameter space largely unexplored by other relativistic binary pulsars. For example, it displays one of the highest gravitational wave (GW) luminosities of any known binary pulsar, as well as the highest rate or orbital decay due to GW damping. PSR J1757-1854 is also notable in that it is an excellent candidate for exploring new tests of Genera…
The observed TeV light curve from the $γ$-ray binary PSR B1259-63/LS 2883 shows a decrease in the flux at periastron which has not been fully explained by emission mechanisms alone. This observed decrease can, however, be explained by gamma-gamma absorption due to the stellar and disk photons. We calculate the gamma-gamma absorption in PSR B1259-63/LS 2883 taking into account photons from both the circumstellar disk and star, assuming the $γ$ rays originate at the position of the pulsar. The gamma-gamma absorption due to the circumstellar disk photons produces a $\approx14\%$ decrease in the f…
In recent years, the Fermi-LAT gamma-ray telescope has detected a population of over 160 gamma-ray pulsars, which has enabled the detailed study of electromagnetic radiation from pulsars at energies above 100 MeV. Further, since the surprising detection of the Crab pulsar in very high-energy (VHE; E > 100 GeV) gamma rays by the MAGIC and VERITAS collaborations, there has been an ongoing effort in the astrophysics community to detect new pulsars in the VHE band. However, the Crab remains the only pulsar so far detected in VHE gamma rays, raising the question of whether or not the Crab is unique…
The PSR J1023+0038 binary system hosts a neutron star and a low-mass, main-sequence-like star. It switches on year timescales between states as an eclipsing radio millisecond pulsar and a low-mass X-ray binary. We present a multi-wavelength observational campaign of PSR J1023+0038 in its most recent low-mass X-ray binary state. Two long XMM-Newton observations reveal that the system spends ~70% of the time in a $\approx$$3\times10^{33}$ erg/s X-ray luminosity mode, which, as shown in Archibald et al. (2014), exhibits coherent X-ray pulsations. This emission is interspersed with frequent lower …
The orbital parameters of gamma-ray binary PSR~J2032+4127
Nanjing Normal University（南京师范大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；China West Normal University（西华师范大学）；Nanjing University（南京大学）
We report the first hard X-ray (3-79 keV) observations of the millisecond pulsar (MSP) binary PSR J1023+0038 using NuSTAR. This system has been shown transiting between a low-mass X-ray binary (LMXB) state and a rotation-powered MSP state. The NuSTAR observations were taken in both LMXB state and rotation-powered state. The source is clearly seen in both states up to ~79 keV. During the LMXB state, the 3-79 keV flux is about a factor of 10 higher that in the rotation-powered state. The hard X-rays show clear orbital modulation during the X-ray faint rotation-powered state but the X-ray orbital…
PSR B1259-63/LS 2883 is a very high energy (VHE; $E > 100$ GeV) γ-ray emitting binary consisting of a 48 ms pulsar orbiting around a Be star with a period of $\sim3.4$ 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 γγ-absorption, leaving a characteristic imprint in the observed spectrum of the high energy emission. At GeV energies, the source was detected for the fir…
The radio and gamma-ray pulsar PSR J2032+4127 was recently found to be in a decades-long orbit with the Be star MT91 213, with the pulsar moving rapidly towards periastron. This binary shares many similar characteristics with the previously unique binary system PSR B1259-63/LS 2883. Here, we describe radio, X-ray, and optical monitoring of PSR J2032+4127/MT91 213. Our extended orbital phase coverage in radio, supplemented with Fermi gamma-ray data, allows us to update and refine the orbital period to 45-50 yr and time of periastron passage to 2017 November. We analyse archival and recent Chand…
The pulsar/massive star binary system PSR B1259-63 / LS 2883 is one of the best-studied gamma-ray binaries, a class of systems whose bright gamma-ray flaring can provide important insights into high-energy physics. Using the Australian Long Baseline Array we have conducted very long baseline interferometric observations of PSR B1259-63 over 4.4 years, fully sampling the 3.4-year orbital period. From our measured parallax of $0.38\pm0.05$ mas we use a Bayesian approach to infer a distance of $2.6^{+0.4}_{-0.3}$ kpc. We find that the binary orbit is viewed at an angle of $154\pm3$ degrees to the…
We report on the first NuSTAR observation of the gamma-ray emitting millisecond pulsar binary PSR J1723-2837. X-ray radiation up to 79 keV is clearly detected and the simultaneous NuSTAR and Swift spectrum is well described by an absorbed power-law with a photon index of ~1.3. We also find X-ray modulations in the 3-10 keV, 10-20 keV, 20-79 keV, and 3-79 keV bands at the 14.8-hr binary orbital period. All these are entirely consistent with previous X-ray observations below 10 keV. This new hard X-ray observation of PSR J1723-2837 provides strong evidence that the X-rays are from the intrabinar…
We analyze photometry and spectra of the "redback" millisecond pulsar binary J2339$-$0533. These observations include new measurements from Keck and GROND, as well as archival measurements from the OISTER, WIYN, SOAR, and HET telescopes. The parameters derived from GROND, our primary photometric data, describe well the rest of the datasets, raising our confidence in our fitted binary properties. Our fit requires hot-spots (likely magnetic poles) on the surface of the companion star, and we see evidence that these spots move over the 8 yr span of our photometry. The derived binary inclination $…
