We report the detection of pulsed gamma-rays from the young, spin-powered radio pulsar PSR J2021+3651 using data acquired with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST). The light curve consists of two narrow peaks of similar amplitude separated by 0.468 +/- 0.002 in phase. The first peak lags the maximum of the 2 GHz radio pulse by 0.162 +/- 0.004 +/- 0.01 in phase. The integral gamma-ray photon flux above 100 MeV is (56 +/- 3 +/- 11) x 10^{-8} /cm2/s. The photon spectrum is well-described by an exponentially cut-off power law of the form dF/dE = kE^{-Γ} e^(-E/E_c) where the energy E is expressed in GeV. The photon index is Γ= 1.5 +/- 0.1 +/- 0.1 and the exponential cut-off is E_c = 2.4 +/- 0.3 +/- 0.5 GeV. The first uncertainty is statistical and the second is systematic. The integral photon flux of the bridge is approximately 10% of the pulsed emission, and the upper limit on off-pulse gamma-ray emission from a putative pulsar wind nebula is <10% of the pulsed emission at the 95% confidence level. Radio polarization measurements yield a rotation measure of RM = 524 +/- 4 rad/m^2 but a poorly constrained magnetic geometry. Re-analysis of Chandra data enhanced the significance of the weak X-ray pulsations, and the first peak is roughly phase-aligned with the first gamma-ray peak. We discuss the emission region and beaming geometry based on the shape and spectrum of the gamma-ray light curve combined with radio and X-ray measurements, and the implications for the pulsar distance. Gamma-ray emission from the polar cap region seems unlikely for this pulsar.
On the mechanism of the pulsed high energy emission from the pulsar PSR B1509-58
研究了脉冲星PSR B 1509 -58的高能（$<1$ GeV）辐射及其与1.4GHz射电辐射的关系。准线性扩散在产生脉冲HE辐射的作用进行了研究。我们表明，通过回旋不稳定性的相对较低的频率波激发，这是由于扩散过程的影响粒子分布函数和开关的同步辐射机制。我们认为，HE主峰和射电脉冲的重合是脉冲星磁层局部区域同时产生高频和低频辐射的直接结果。在本文中，我们还考虑了无线电计数器脉冲的情况下，并解释了这一事实。
The radio-quiet pulsar PSR J2021+4026 is mostly known because it is the only rotation-powered pulsar that shows variability in its γ-ray emission. Using XMM-Newton archival data, we first confirmed that its flux is steady in the X-ray band, and then we showed that both the spectral and timing X-ray properties, i.e. the narrow pulse profile, the high pulsed fraction of 80-90% and its dependence on the energy, can be better reproduced using a magnetized atmosphere model instead of a simply blackbody. With a maximum likelihood analysis in the energy-phase space, we inferred that the pulsar has, i…
We report the detection of the pulsed signal of the radio-quiet magnetar-like pulsar PSR J1846-0258 in the high-energy \gr-ray data of the Fermi Large Area Telescope (Fermi LAT). We produced phase-coherent timing models exploiting RXTE PCA and Swift XRT monitoring data for the post- (magnetar-like) outburst period from 2007 August 28 to 2016 September 4, with independent verification using INTEGRAL ISGRI and Fermi GBM data. Phase-folding barycentric arrival times of selected Fermi LAT events from PSR J1846-0258, resulted in a 4.2 sigma detection (30--100 MeV) of a broad pulse consistent in sha…
Discovery of Short-Term γ-Ray Pulsed Radiation Variations Following a Glitch in PSR J0205+6449
State Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所粒子天体物理国家重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics and Institute of Theoretical Physics, Nanjing Normal University（南京师范大学物理科学与技术学院理论物理研究所）
We report on simultaneous X-ray and radio observations of the radio-mode-switching pulsar PSR B1822-09 with ESA's XMM-Newton and the WSRT, GMRT and Lovell radio telescopes. PSR B1822-09 switches between a radio-bright and radio-quiet mode, and we discovered a relationship between the durations of its modes and a known underlying radio-modulation timescale within the modes. We discovered X-ray (energies 0.2-1.4 keV) pulsations with a broad sinusoidal pulse, slightly lagging the radio main pulse in phase by 0.094 +/- 0.017, with an energy-dependent pulsed fraction varying from ~0.15 at 0.3 keV t…
We investigate the supernova remnant (SNR) 3C 397 and its neighboring pulsar PSR J1906+0722 in high energy gamma rays by using nearly six years of archival data of {\it Large Area Telescope} on board {\it Fermi Gamma Ray Space Telescope} (Fermi-LAT). The off-pulse analysis of gamma-ray flux from the location of PSR J1906+0722 reveals an excess emission which is found to be very close to the radio location of 3C 397. Here, we present the preliminary results of this gamma-ray analysis of 3C 397 and PSR J1906+0722.
The transitional millisecond pulsar PSR\,J1023+0038 is the first millisecond pulsar discovered to emit UV and optical pulses. Here we present the results of the UV and X-ray phase-resolved timing analysis of observations performed with the Hubble Space Telescope, \textit{XMM-Newton} and NuSTAR satellites between 2014 and 2021. Ultraviolet pulsations are detected in the high luminosity mode and disappear during low and flaring modes, similar to what is observed in the X-ray band. In the high mode, we find variability in both the UV and X-ray pulse amplitudes. The root mean square pulsed amplitu…
We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf (WD) companions. PSR J0636+5129 is a MSP in a very tight 96-min orbit with a low-mass, 8 $M_J$ companion. PSR J0645+5158 is a nearby, isolated MSP with a very small duty cycle (1-2%), which has led to its inclusion in high-precision pulsar timing programs. Using data from XMM-Newton, we have analyze…
We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray timing and spectroscopy of the three exceptionally energetic rotation-powered millisecond pulsars PSRs B1821-24, B1937+21, and J0218+4232. By correcting the NuSTAR onboard clock for phase and frequency drifts between observation intervals, we are able to recover the intrinsic hard X-ray pulse profiles of all three pulsars with a resolution down to < 15 microsec. The substantial reduction of background emission relative to previous broadband X-ray observations allows us to detect for the first time pulsed emission up to ~50 ke…
The TRAPUM collaboration has used the MeerKAT telescope to conduct a search for pulsed radio emission from the young Small Magellanic Cloud pulsar J0058-7218 located in the supernova remnant IKT 16, following its discovery in X-rays with XMM-Newton. We report no significant detection of dispersed, pulsed radio emission from this source in three 2-hour L-band observations using the core dishes of MeerKAT, setting an upper limit of 7.0 μJy on its mean flux density at 1284 MHz. This is nearly 7 times deeper than previous radio searches for this pulsar in Parkes L-band observations. This suggests …
古老的脉冲星PSR B 0943 +10（P=1.1 s，特征年龄τ = 500万年）是模式转换射电脉冲星的最佳例子。它的无线电发射在具有规则漂移子脉冲的高度组织状态（B模式）和混沌发射模式（Q模式）之间交替。我们提出了XMM-牛顿观测的结果，表明PSR B 0943 +10的X射线特性取决于其射电状态（Hermsen等人，2013）。在无线电微弱状态（Q模式）期间，X射线通量比B模式期间大两倍以上，并且检测到具有约50%脉冲分数的X射线脉冲。PSR B 0943 +10的B模X射线发射可以用热发射来描述，黑体温度kT=0.26 keV，来自一个亮度为7 × 10^28 erg/s的小热点，与部分屏蔽能隙模型的预测相一致，这也解释了该模的射电发射特性。我们推导出B模式下X射线脉冲分数的上限为46%，与从无线电数据推断的PSR B 0943 +10的几何形状和视角一致。在Q模式期间观察到的较高通量与具有光子指数为2.2的幂律谱的附加分量的出现一致。我们将其解释为恒星磁层中产生的脉冲非热X射线。负责非热发射的粒子的波束模式或加速效率的微小变化可以解释无线电B模式期间该分量的通量减少。
Aims. We provide new insights into the nature of HESS J1857+026, a very-high-energy γ-ray source whose complex morphology in the TeV band was attributed to the superposition of two distinct sources. Methods. We performed radio continuum observations to look for the pulsar wind nebula and the supernova remnant associated with the pulsar PSR J1856+0245, which might be powering part of the γ-ray emission. We observed HESS J1857+026 with the Karl G. Jansky Very Large Array (VLA) at 1.5 GHz in the C configuration. In addition, using the same array configuration, we observed a region of $0.4^\circ \…
High-energy observations of PSR B1259-63/LS 2883 through the 2014 periastron passage: connecting X-rays to the GeV flare
PSR B1259-63/LS 2883双星系统在射电、X射线和TeV伽马射线中都有很好的采样，并且在这些频率上显示出轨道相位相关的变化。第一次探测到来自该系统的GeV伽马射线是在2010年的近星点附近。在这封信中，我们提出了对Swift/XRT，NuSTAR/FPM和Fermi/LAT获得的X射线和伽马射线数据的分析，通过最近发生在2014年5月4日的近星点通过。虽然PSR B1259-63/LS 2883在此之前和期间没有被LAT检测到，但我们表明GeV耀斑发生在与2011年初相似的轨道相位，从而确定了近星点后GeV耀斑的重复性。观测到多次耀斑，每次耀斑持续数天，也观察到短期变化。我们还发现X射线通量的变化与GeV耀斑同期的第一次。宽频带的高能光谱是keV到GeV之间联系的有力证据，我们将其解释为来自冲击脉冲星风的同步辐射。
We report on orbital modulation of the 100-600 MeV gamma-ray emission of the $P_{\rm B}=4.6$ hr millisecond pulsar binary PSR J2339$-$0533 using 11 yr of Fermi Large Area Telescope data. The modulation has high significance (chance probability $p\approx 10^{-7}$), is approximately sinusoidal, peaks near pulsar superior conjunction, and is detected only in the low-energy 100-600 MeV band. The modulation is confined to the on-pulse interval, suggesting that the variation is in the 2.9-ms pulsed signal itself. This contrasts with the few other known systems exhibiting GeV orbital modulations, as …
Simultaneous observations of PSR B0823+26 with ESA's XMM-Newton, the Giant Metrewave Radio Telescope and international stations of the Low Frequency Array revealed synchronous X-ray/radio switching between a radio-bright (B) mode and a radio-quiet (Q) mode. During the B mode we detected PSR B0823+26 in 0.2$-$2 keV X-rays and discovered pulsed emission with a broad sinusoidal pulse, lagging the radio main pulse by 0.208 $\pm$ 0.012 in phase, with high pulsed fraction of 70$-$80%. During the Q mode PSR B0823+26 was not detected in X-rays (2 $σ$ upper limit a factor ~9 below the B-mode flux). The…
Flux Evolution of PSR B0540--69 and the Spectral Energy Distribution of its Pulsar Wind Nebula
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Central China Normal University（华中师范大学）；Nanjing Normal University（南京师范大学）；TIANFU Cosmic Ray Research Center（天府宇宙线研究中心）
We report the discovery of soft X-ray pulsations from the nearby millisecond pulsar PSR J1231$-$1411 using NICER. The pulsed emission is characterized by a broad and asymmetric main pulse and a much fainter secondary interpulse, with a total pulsed count rate of 0.055 c s$^{-1}$ in the 0.35-1.5 keV band. We analyzed Fermi LAT data to update the pulse timing model covering 10 years of data and used that model to coherently combine NICER data over a year of observations. Spectral modeling suggests that the flux is dominated by thermal emission from a hot spot (or spots) on the neutron star surfa…
We report on simultaneous X-ray and radio observations of the mode-switching pulsar PSR B0943+10 obtained with the XMM-Newton satellite and the LOFAR, LWA and Arecibo radio telescopes in November 2014. We confirm the synchronous X-ray/radio switching between a radio-bright (B) and a radio-quiet (Q) mode, in which the X-ray flux is a factor ~2.4 higher than in the B-mode. We discovered X-ray pulsations, with pulsed fraction of 38+/-5% (0.5-2 keV), during the B-mode, and confirm their presence in Q-mode, where the pulsed fraction increases with energy from ~20% up to ~65% at 2 keV. We found marg…
We report our analysis of the Fermi Large Area Telescope data for 39 millisecond pulsars (MSPs) listed in the second $γ$-ray pulsar catalog. Spectra of the pulsars are obtained. We fit the spectra with a function of a power law with exponential cutoff, and find the best-fit parameters of photon index $Γ= 1.54^{+0.10}_{-0.11}$ and cutoff energy $E_{c} = 3.70^{+0.95}_{-0.70}$ GeV. This spectral shape, which includes the intrinsic differences in the spectra of the MSPs, can be used for finding candidate MSPs and unidentified types of sources detected by Fermi at high Galactic latitudes. In one of…
New simultaneous X-ray and radio observations of the archetypal mode-switching pulsar PSR B0943+10 have been carried out with XMM-Newton and the LOFAR, LWA and Arecibo radio telescopes in November 2014. They allowed us to better constrain the X-ray spectral and variability properties of this pulsar and to detect, for the first time, the X-ray pulsations also during the X-ray-fainter mode. The combined timing and spectral analysis indicates that unpulsed non-thermal emission, likely of magnetospheric origin, and pulsed thermal emission from a small polar cap are present during both radio modes …
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…
More than 100 rotating radio transients (RRATs) have been discovered since 2006. However, it is unclear whether RRATs radiate in the nulling states. PSR J0628+0909 has been classified as an RRAT. In this paper, we study the single pulses and integrated pulse profile of PSR J0628+0909 to check whether we can detect pulsed radio emission in the nulling states. We also aim to study the polarization of the RRAT and its relationship to the general pulsar population. We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to observe PSR J0628+0909 in the frequency range from 1.0 to …
Temporal and spectral evolution in X- and gamma-rays of magnetar 1E 1547.0-5408 since its October 2008 outburst: the discovery of a transient hard pulsed component after its January 2009 outburst
磁星1 E 1547.0-5408在2008年10月和2009年1月爆发。在本文中，我们详细介绍了从2008年10月3日开始到2011年1月结束的1 E 1547.0-5408在~1和300 keV之间持续总发射和脉冲发射的时间和光谱特征的演变。我们分析了罗西X射线计时探测器，国际伽马射线天体物理实验室和斯威夫特卫星收集的数据。
The emission from PSR J1107-5907 is erratic. Sometimes the radio pulse is undetectable, at other times the pulsed emission is weak, and for short durations the emission can be very bright. In order to improve our understanding of these state changes, we have identified archival data sets from the Parkes radio telescope in which the bright emission is present, and find that the emission never switches from the bright state to the weak state, but instead always transitions to the off state. Previous work had suggested the identification of the off state as an extreme manifestation of the weak st…
We have carried out high frequency radio observations of the high magnetic field pulsar PSR J1119-6127 following its recent X-ray outburst. While initial observations showed no evidence of significant radio emission, subsequent observations detected pulsed emission across a large frequency band. In this letter, we report on the initial disappearance of the pulsed emission and its prompt reactivation and dramatic evolution over several months of observation. The periodic pulse profile at S-band (2.3 GHz) after reactivation exhibits a multi-component emission structure, while the simultaneous X-…
We report on Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of the young rotation-powered radio pulsar PSR B1509$-$58 in the supernova remnant MSH 15$-$52. We confirm the previously reported curvature in the hard X-ray spectrum, showing that a log parabolic model provides a statistically superior fit to the spectrum compared with the standard power law. The log parabolic model describes the NuSTAR data, as well as previously published gamma-ray data obtained with COMPTEL and AGILE, all together spanning 3 keV through 500 MeV. Our spectral modelling allows us to constrai…
We discuss X-ray and gamma-ray emissions from Crab-like pulsars, PSRs~J0537-6910 and~J0540-6919, in Large Magellanic Cloud. Fermi-LAT observations have resolved the gamma-ray emissions from these two pulsars and found the pulsed emissions from PSR~J0540-6919. The total pulsed radiation in the X-ray/gamma-ray energy bands of PSR~J0540-6919 is observed with the efficiency $η_{J0540}\sim 0.06$ (in 4$π$ sr), which is about a factor of ten larger than $η_{Crab}\sim 0.006$ of the Crab pulsar. Although PSR~J0537-6910 has the highest spin-down power among currently known pulsars, the efficiency of the…
PSR J1023+0038 is the first millisecond pulsar discovered to pulsate in the visible band; such a detection took place when the pulsar was surrounded by an accretion disk and also showed X-ray pulsations. We report on the first high time resolution observational campaign of this transitional pulsar in the disk state, using simultaneous observations in the optical (TNG, NOT, TJO), X-ray (XMM-Newton, NuSTAR, NICER), infrared (GTC) and UV (Swift) bands. Optical and X-ray pulsations were detected simultaneously in the X-ray high intensity mode in which the source spends $\sim$ 70% of the time, and …
We performed deep observations to search for radio pulsations in the directions of 375 unassociated Fermi Large Area Telescope (LAT) gamma-ray sources using the Giant Metrewave Radio Telescope (GMRT) at 322 and 607 MHz. In this paper we report the discovery of three millisecond pulsars (MSPs), PSR J0248+4230, PSR J1207$-$5050 and PSR J1536$-$4948. We conducted follow up timing observations for around 5 years with the GMRT and derived phase coherent timing models for these MSPs. PSR J0248$+$4230 and J1207$-$5050 are isolated MSPs having periodicities of 2.60 ms and 4.84 ms. PSR J1536-4948 is a …
PSR B0943+10 is a mode-switching radio pulsar characterized by two emission modes with different radio and X-ray properties. Previous studies, based on simple combinations of blackbody and power law models, showed that its X-ray flux can be decomposed in a pulsed thermal plus an unpulsed non-thermal components. However, if PSR B0943+10 is a nearly aligned rotator seen pole-on, as suggested by the radio data, it is difficult to reproduce the high observed pulsed fraction unless magnetic beaming is included. In this work we reanalyze all the available X-ray observations of PSR B0943+10 with simu…
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。
The rotational properties and X-ray luminosity of PSR J0726-2612 are close to those of dim isolated neutron stars (XDINs). It was proposed that the source could be the first XDIN with observable pulsed radio emission. We have investigated the long-term evolution of the source to test this possibility in the fallback disc model. Reasonable model curves that can account for the evolution of PSR J0726-2612 consistently with its radio pulsar property are similar to those of high-B radio pulsars with dipole field strength $B_0 \sim$ a few $\times 10^{12}~$G at the pole of the star. In the same mode…
