In this work, we investigated the presence of strictly periodic, as well as quasi-periodic signals, in the timing of the 25 millisecond pulsars from the EPTA DR2 dataset. This is especially interesting in the context of the recent hints of a gravitational wave background in these data, and the necessary further study of red-noise timing processes, which are known to behave quasi-periodically in some normal pulsars. We used Bayesian timing models developed through the run_enterprise pipeline: a strict periodicity was modelled as the influence of a planetary companion on the pulsar, while a quasi-periodicity was represented as a Fourier-domain Gaussian process. We found that neither model would clearly improve the timing models of the 25 millisecond pulsars in this dataset. This implies that noise and parameter estimates are unlikely to be biased by the presence of a (quasi-)periodicity in the timing data. Nevertheless, the results for PSRs J1744--1134 and J1012+5307 suggest that the standard noise models for these pulsars may not be sufficient. We also measure upper limits for the projected masses of planetary companions around each of the 25 pulsars. The data of PSR J1909--3744 yielded the best mass limits, such that we constrained the 95-percentile to 2*10^{-4} Earth-masses (roughly the mass of the dwarf planet Ceres) for orbital periods between 5 d--17 yr. These are the best pulsar planet mass limits to date.
Detection of a Millisecond Periodicity in BATSE Short Gamma-Ray Bursts
School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, China（教育部现代天文学与天体物理重点实验室（南京大学））；Institute for Astrophysics, School of Physics, Zhengzhou University（郑州大学物理学院天体物理研究所）；Department of Physics, The University of Hong Kong（香港大学物理系）；The Hong Kong Institute for Astronomy and Astrophysics, The University of Hong Kong（香港大学香港天文学与天体物理研究所）
We report on the detection of quasi-periodic micro-structure in three millisecond pulsars (MSPs), PSRs J1022+1001, J2145-0750 and J1744-1134, using high time resolution data acquired with the Large European Array for Pulsars at a radio frequency of 1.4 GHz. The occurrence rate of quasi-periodic micro-structure is consistent among pulses with different peak flux densities. Using an auto-correlation analysis, we measure the periodicity and width of the micro-structure in these three pulsars. The detected micro-structure from PSRs J1022+1001 and J1744-1134 is often highly linearly polarised. In P…
We report optical modulation of the companion to the X-ray source U18 in the globular cluster NGC 6397. U18, with combined evidence from radio and X-ray measurements, is a strong candidate as the second redback in this cluster, initially missed in pulsar searches. This object is a bright variable star with an anomalous red color and optical variability (\sim 0.2 mag in amplitude) with a periodicity \sim 1.96 days that can be interpreted as the orbital period. This value corresponds to the longest orbital period for known redback candidates and confirmed systems in Galactic globular clusters an…
Searching for links between energetic millisecond pulsars and repeating fast radio bursts
Anton Pannekoek Institute for Astronomy, University of Amsterdam（阿姆斯特丹大学安东·潘内科克天文学研究所）；ASTRON, Netherlands Institute for Radio Astronomy（荷兰射电天文研究所 ASTRON）；Department of Physics, McGill University（麦吉尔大学物理系）；Trottier Space Institute, McGill University（麦吉尔大学特罗蒂尔太空研究所）；Joint institute for VLBI ERIC（甚长基线干涉测量联合研究所 ERIC）；CSIRO Space and Astronomy, Australia Telescope National Facility（澳大利亚联邦科学与工业研究组织空间与天文部，澳大利亚望远镜国家设施）
Pulsar science with data from the Large European Array for Pulsars
大型欧洲脉冲星阵列（英语：Large European Array for Pulsars，LEAP）是欧洲的一个脉冲星定时阵列计划，它将洛弗尔、埃弗尔斯贝格、南赛、撒丁岛和韦斯特博克的射电望远镜组合成一个单一的捆绑阵列，并每月对一组毫秒脉冲星（英语：milliseconds pulsar，MSP）进行观测。我们的实验概述见Bassa et al.（2016）。基带数据以1396 MHz的中心频率和每个望远镜128 MHz的带宽记录，并使用专用相关器在Jodrell Bank天文台的集群上进行离线相关，详细信息见Smits et al.（2017）。LEAP提供了比单个望远镜更高的灵敏度，并且可以在定时和成像模式下运行（特别是在银河系中心射电磁星的观测中; Wucknitz 2015）。到目前为止，已经减少了4年的观察。在这里，我们报告了利用LEAP数据的科学项目。
Fast radio bursts (FRBs) are millisecond-duration flashes of radio waves that are visible at distances of billions of light-years. The nature of their progenitors and their emission mechanism remain open astrophysical questions. Here we report the detection of the multi-component FRB 20191221A and the identification of a periodic separation of 216.8(1) ms between its components with a significance of 6.5 sigmas. The long (~3 s) duration and nine or more components forming the pulse profile make this source an outlier in the FRB population. Such short periodicity provides strong evidence for a …
Fast radio bursts (FRBs) are bright, millisecond-duration radio transients originating from extragalactic distances. Their origin is unknown. Some FRB sources emit repeat bursts, ruling out cataclysmic origins for those events. Despite searches for periodicity in repeat burst arrival times on time scales from milliseconds to many days, these bursts have hitherto been observed to appear sporadically, and though clustered, without a regular pattern. Here we report the detection of a $16.35\pm0.15$ day periodicity (or possibly a higher-frequency alias of that periodicity) from a repeating FRB 180…
Using data from the Large European Array for Pulsars (LEAP), and the Effelsberg telescope, we study the scintillation parameters of the millisecond pulsar J0613-0200 over a 7 year timespan. The "secondary spectrum" -- the 2D power spectrum of scintillation -- presents the scattered power as a function of time delay, and contains the relative velocities of the pulsar, observer, and scattering material. We detect a persistent parabolic scintillation arc, suggesting scattering is dominated by a thin, anisotropic region. The scattering is poorly described by a simple exponential tail, with excess …
Time-domain analysis of an archival XMM-Newton observation unveiled a very unusual variability pattern in the soft X-ray emission of PSR J1311-3430, a black widow millisecond pulsar in a tight binary (P_B=93.8 min) with a very low-mass (M~0.01 Msun) He companion star, known to show flaring emission in the optical and in the X-rays. A series of six pulses with a regular recurrence time of ~124 min is apparent in the 0.2-10 keV light curve of the system, also featuring an initial, bright flare and a quiescent phase lasting several hours. The X-ray spectrum does not change when the pulses are see…
Long-period thermal oscillations in superfluid millisecond pulsars
在以前的论文中，我们已经证明，当中子星的旋转速度减慢时，由于粒子混合物的逐渐变化，它的内部会被加热（旋转化学加热）。在以前研究的情况下（非超流中子星或只有修改Urca反应的超流星），这导致了一个准稳态，其中恒星辐射热光子很长一段时间，可能解释了从毫秒脉冲星J 0437 -4715观察到的紫外线辐射。第一次，我们探讨了旋转化学加热与直接Urca反应和均匀和各向同性的超流能隙的不同大小的现象。我们首先做探索性的工作，通过整合的热和化学演化方程数值不同的能隙，揭示了丰富的现象学的稳定和不稳定的解决方案。为了理解这些，我们围绕准稳态进行稳定性分析，确定增长，衰减和振荡解决方案的特征时间。对于小的差距，现象是类似于以前研究的情况下，在这个意义上说，解决方案迅速收敛到一个准稳态。对于大的能隙（$\gtrsim 0.05$ MeV），这些解变得不稳定，导致周期性的极限环行为（$\sim 10^{6-7} yr, in which the star is hot ($ T_s \gtrsim 10^5 $ K) for a small fraction of the cycle ($ \sim 5- 20%$），并且冷的时间更长。
On the Deepest Search for Galactic Center Pulsars and an Examination of an Intriguing Millisecond Pulsar Candidate
Columbia University（哥伦比亚大学）；SETI Institute（SETI研究所）；University of California, Berkeley（加州大学伯克利分校）；National Radio Astronomy Observatory（美国国家射电天文台）；University of Oxford（牛津大学）
Recently, repeating fast radio bursts (FRBs) with a period of $P_{\rm FRB}=16.35\pm0.18$ days from FRB 180916.J0158+65 had been reported. It still remains controversial how to give rise to such a periodicity of this FRB. In this Letter, based on an assumption of a young pulsar surrounding by a debris disk, we attempt to diagnose whether the Lense-Thirring precession of the disk on the emitter can produce the observed periodicity. Our calculations indicate that the Lense-Thirring effect of a tilted disk can result in a precession period of 16 days for a mass inflow rate of $0.5-1.5\times10^{18}…
We report on a discovery of a promising candidate as a black widow millisecond pulsar binary, 4FGL J0336.0+7502, which shows many pulsar-like properties in the 4FGL-DR2 catalog. Within the 95% error region of the LAT source, we identified an optical counterpart with a clear periodicity at P(orb) = 3.718178(9) hours using the Bohyunsan 1.8-m Telescope, Lulin One-meter Telescope, Canada-France-Hawaii Telescope, and Gemini-North. At the optical position, an X-ray source was marginally detected in the Swift/XRT archival data, and the detection was confirmed by our Chandra/ACIS DDT observation. The…
In this work we study variations in the parabolic scintillation arcs of the binary millisecond pulsar PSR J1643-1224 over five years using the Large European Array for Pulsars (LEAP). The 2D power spectrum of scintillation, called the secondary spectrum, often shows a parabolic distribution of power, where the arc curvature encodes the relative velocities and distances of the pulsar, ionised interstellar medium (IISM), and Earth. We observe a clear parabolic scintillation arc which varies in curvature throughout the year. The distribution of power in the secondary spectra are inconsistent with…
We report the properties of more than 800 bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio telescope (FAST) during an extremely active episode on UTC September 25th-28th, 2021 in a series of four papers. In this fourth paper of the series, we present a systematic search of the spin period and linear acceleration of the source object from both 996 individual pulse peaks and the dedispersed time series. No credible spin period was found from this data set. We rule out the presence of significant periodicity in the…
We present results from the search for a stochastic gravitational-wave background (GWB) as predicted by the theory of General Relativity using six radio millisecond pulsars from the Data Release 2 (DR2) of the European Pulsar Timing Array (EPTA) covering a timespan up to 24 years. A GWB manifests itself as a long-term low-frequency stochastic signal common to all pulsars, a common red signal (CRS), with the characteristic Hellings-Downs (HD) spatial correlation. Our analysis is performed with two independent pipelines, \eprise{} and \tn{}+\ftwo{}, which produce consistent results. A search for…
Xiangtan University（湘潭大学）；Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；Nanjing Normal University（南京师范大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
The fast Fourier transform (FFT) based periodicity search methods provide an efficient way to search for millisecond and binary pulsars but encounter significant sensitivity degradation while searching for long period and short duty cycle pulsars. An alternative to FFT-based search methods called the Fast Folding Algorithm (FFA) search, provides superior sensitivity to search for signals with long periods and short duty cycles. In the GMRT High Resolution Southern Sky (GHRSS) survey, we are using an FFA-based pipeline to search for isolated pulsars in a period range of 100 ms to 100 s. We have…
Discovery of 51 pulsars in a reanalysis of the Green Bank North Celestial Cap Survey and a revised pulsar census
Max Planck Institute for Gravitational Physics (Albert Einstein Institute)（马克斯·普朗克引力物理研究所（爱因斯坦研究所））；Leibniz Universität Hannover（汉诺威莱布尼茨大学）；Center for Gravitation, Cosmology, and Astrophysics, Department of Physics and Astronomy, University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校物理与天文学系引力、宇宙学与天体物理中心）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理学与超级计算中心）；Department of Physics and Astronomy, University of British Columbia（不列颠哥伦比亚大学物理与天文学系）；Department of Physics and Astronomy, Vanderbilt University（范德堡大学物理与天文学系）；Department of Physics and Astronomy, George Mason University（乔治梅森大学物理与天文学系）
Improving timing sensitivity in the microhertz frequency regime: limits from PSR J1713$+$0747 on gravitational waves produced by super-massive black-hole binaries
We report on Bayesian estimation of the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740$+$6620, conditional on pulse-profile modeling of Neutron Star Interior Composition Explorer X-ray Timing Instrument (NICER XTI) event data. We condition on informative pulsar mass, distance, and orbital inclination priors derived from the joint NANOGrav and CHIME/Pulsar wideband radio timing measurements of arXiv:2104.00880. We use XMM European Photon Imaging Camera spectroscopic event data to inform our X-ray likelihood function. The prior support of the pulsar radius is t…
