A5019134962- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Gamma-ray bursts and supernovae
- Advanced Frequency and Time Standards
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- High-pressure geophysics and materials
- GNSS positioning and interference
- Ionosphere and magnetosphere dynamics
- Superconducting Materials and Applications
- Astronomical Observations and Instrumentation
- Particle accelerators and beam dynamics
- Atomic and Subatomic Physics Research
- Mechanics and Biomechanics Studies
- Geophysics and Sensor Technology
- Particle Accelerators and Free-Electron Lasers
- Gyrotron and Vacuum Electronics Research
- Computer Graphics and Visualization Techniques
- Superconducting and THz Device Technology
- Geological and Geophysical Studies
- 3D Shape Modeling and Analysis
Guangxi University
2020-2025
Max Planck Institute for Radio Astronomy
2011-2024
University of Manchester
2011-2021
Observatoire de Paris
2014-2021
Centre National de la Recherche Scientifique
2014-2020
National Institute of Metrology
2016
Université d'Orléans
2014
Laboratoire de Physique et Chimie de l’Environnement et de l’Espace
2014
We report on the high-precision timing of 42 radio millisecond pulsars (MSPs) observed by European Pulsar Timing Array (EPTA). This EPTA Data Release 1.0 extends up to mid-2014 and baselines range from 7-18 years. It forms basis for stochastic gravitational-wave background, anisotropic continuous-wave limits recently presented elsewhere. The Bayesian analysis performed with TempoNest yields detection several new parameters: seven parallaxes, nine proper motions and, in case six binary...
We present results from the search for a stochastic gravitational-wave background (GWB) as predicted by theory of General Relativity using six radio millisecond pulsars Data Release 2 (DR2) European Pulsar Timing Array (EPTA) covering timespan up to 24 years. A GWB manifests itself long-term low-frequency signal common all pulsars, red (CRS), with characteristic Hellings-Downs (HD) spatial correlation. Our analysis is performed two independent pipelines, \eprise{} and \tn{}+\ftwo{}, which...
In this paper, we describe the International Pulsar Timing Array second data release, which includes recent pulsar timing obtained by three regional consortia: European Array, North American Nanohertz Observatory for Gravitational Waves, and Parkes Array. We analyse where possible combine high-precision 65 millisecond pulsars are regularly observed these groups. A basic noise analysis, including processes both correlated uncorrelated in time, provides models ephemerides pulsars. find that...
The discovery of radio pulsars in compact orbits around Sgr A* would allow an unprecedented and detailed investigation the spacetime this supermassive black hole. This paper shows that pulsar timing, including a single pulsar, has potential to provide novel tests general relativity, particular its cosmic censorship conjecture no-hair theorem for rotating holes. These experiments can be performed by timing observations with 100 μs precision, achievable Square Kilometre Array normal at...
Symmetries play an important role in modern theories of gravity. The strong equivalence principle (SEP) constitutes a collection gravitational symmetries which are all implemented by general relativity. Alternative theories, however, generally expected to violate some aspects SEP. We test three SEP using observed change rates the orbital period and eccentricity binary pulsar J1713+0747: 1. constant's constancy as part locational invariance gravitation; 2. post-Newtonian parameter...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this has frequency 4-5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favor presence CGW over common uncorrelated noise process, while estimates p-value to...
Abstract The Imaging X-ray Polarimetry Explorer measured with high significance the polarization of brightest Z-source, Sco X-1, resulting in nominal 2–8 keV energy band a degree 1.0% ± 0.2% and angle 8° 6° at 90% confidence level. This observation was strictly simultaneous observations performed by NICER, NuSTAR, Insight-HXMT, which allowed for precise characterization its broadband spectrum from soft to hard X-rays. source has been observed mainly state, short periods flaring. We also...
ABSTRACT We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from International Pulsar Timing Array (IPTA). used two analysis techniques with independent estimates noise models for pulsar and different algorithms obtaining time-scale. The analyses agree within estimated uncertainties both TT(BIPM17), post-corrected time-scale produced by Bureau des Poids et Mesures (BIPM). show that methods could detect significant...
Abstract This paper reports the first detection of polarization in X-rays for atoll-source 4U 1820−303, obtained with Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed radio Australia Telescope Compact Array. The IXPE observations 1820−303 coordinated Swift Telescope, Neutron Star Interior Composition Explorer, and Nuclear Spectroscopic Array aiming to obtain an accurate spectral model covering a broad...
The sensitivity of Pulsar Timing Arrays to gravitational waves depends on the noise present in individual pulsar timing data. Noise may be either intrinsic or extrinsic pulsar. Intrinsic sources will include rotational instabilities, for example. Extrinsic contributions from physical processes which are not sufficiently well modelled, example, dispersion and scattering effects, analysis errors instrumental instabilities. We results a 42 millisecond pulsars (MSPs) observed with European...
ABSTRACT The European Pulsar Timing Array (EPTA) collaboration has recently released an extended data set for six pulsars (DR2) and reported evidence a common red noise signal. Here we present analysis each of the pulsars. We consider several types noise: (i) radio frequency independent, ‘achromatic’, time-correlated noise; (ii) variations dispersion measure scattering; (iii) system band (iv) deterministic signals (other than gravitational waves) that could be in PTA data. perform Bayesian...
ABSTRACT In this work, we study variations in the parabolic scintillation arcs of binary millisecond pulsar PSR J1643−1224 over five years using Large European Array for Pulsars (LEAP). The two-dimensional (2D) power spectrum scintillation, called secondary spectrum, often shows a distribution power, where arc curvature encodes relative velocities and distances pulsar, ionized interstellar medium, Earth. We observe clear arc, which varies throughout year. spectra is inconsistent with single...
In order to reach the sensitivity required detect gravitational waves, pulsar timing array experiments need mitigate as much noise possible in data. A dominant amount of is likely due variations dispersion measure. To correct for such variations, we develop a statistical method inspired by maximum likelihood estimator and optimal filtering. Our consists two major steps. First, spectral index amplitude measure are measured via time-domain analysis. Second, linear filter constructed based on...
ABSTRACT We report on a high-precision timing analysis and an astrophysical study of the binary millisecond pulsar, PSR J1909−3744, motivated by accumulation data with well improved quality over past decade. Using 15 yr observations Nançay Radio Telescope, we achieve precision approximately 100 ns. verify our results using both broad-band sub-band template matching methods to create pulse time-of-arrivals. Compared previous studies, improve measurement secular changes in orbital period...
We report on the coordinated observations of neutron star low-mass X-ray binary (NS-LMXB) GX 5−1 in X-rays (IXPE, NICER, NuSTAR , and INTEGRAL), optical (REM LCO), near-infrared (REM), mid-infrared (VLT VISIR), radio (ATCA). This Z-source was observed by IXPE twice March–April 2023 (Obs. 1 2). In band source detected, but only upper limits to linear polarization were obtained at a 3 σ level 6.1% 5.5 GHz 5.9% 9 Obs. 12.5% 20% 2. The mid-IR, near-IR, suggest presence compact jet that peaks...
Abstract We report on X-ray polarization measurements of the extragalactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in Large Magellanic Cloud, using a ∼850 ks Imaging Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant detected for image-averaged data, giving 99% confidence upper limit (MDP 99 ) 5.3% 2–8 keV energy range. However, phase-resolved analysis detects both nebula pulsar 4–6 For defined as off-pulse phases, degree (PD)...
Millisecond pulsars (MSPs) have been studied in detail since their discovery 1982. The integrated pulse profiles of MSPs appear to be stable, which enables precision monitoring the times arrival (TOAs). However, for individual pulses shape and phase can vary dramatically; this is known as jitter. In paper, we investigate stability five estimate amount jitter PSR J0437−4715. We do not detect intrinsic profile-shape variation based on integration from ∼10–100 s with provided instrumental...
Using data from the Large European Array for Pulsars (LEAP), and Effelsberg telescope, we study scintillation parameters of millisecond pulsar J0613-0200 over a 7 year timespan. The "secondary spectrum" -- 2D power spectrum presents scattered as function time delay, contains relative velocities pulsar, observer, scattering material. We detect persistent parabolic arc, suggesting is dominated by thin, anisotropic region. poorly described simple exponential tail, with excess at high delays;...
The conversion from 2D X-ray to 3D shape holds significant potential for improving diagnostic efficiency and safety. However, existing reconstruction methods often rely on hand-crafted features, manual intervention, prior knowledge, resulting in unstable errors additional processing costs. In this paper, we introduce Swin-X2S, an end-to-end deep learning method directly reconstructing segmentation labeling biplanar orthogonal images. Swin-X2S employs encoder-decoder architecture: the encoder...
Abstract We examined the spatially resolved polarization variations in Crab Nebula over 2 yr, using observational data from Imaging X-ray Polarimetry Explorer, and offer key insights into its magnetic field structures evolution. The results show significant temporal changes degree (PD) across three regions of interest 2–8 keV energy band. Regions (a) (b), located northern southwestern parts study area, exhibit PD with significance levels greater than 4 σ 3 , respectively. Region (c),...
Abstract This work presents a new detailed study on the energy-dependent variation in X-ray polarisation of Crab Pulsar Wind Nebula (PWN), obtained using data from Imaging Polarimetry Explorer (IXPE). For entire PWN, we observed linear degree (PD), and detected rotation angle (PA) with energy at higher than 99.9999 % confidence level. is line indication found Vela PWN by IXPE, it can be interpreted as emitting region polarised photons shrinks increasing energy, leading to PD because they are...
We have studied 4265 giant pulses (GPs) from the millisecond pulsar B1937+21; largest-ever sample gathered for this pulsar, in observations made with Large European Array Pulsars. The pulse energy distribution of GPs associated interpulse are well-described by a power law, index α = −3.99 ± 0.04, while those main best-described broken break occurring at ∼7 Jy |$\mu$|s, power-law indices αlow −3.48 0.04 and αhigh −2.10 0.09. modulation GP emission measured, which found to vary ∼0.5 phases...
Abstract We present Crab X-ray polarization measurements using Imaging X-Ray Polarimetry Explorer (IXPE) data with a total exposure of 300 ks, three times more than the initial 2022 discovery paper. Polarization is detected in pulsar phase bins, revealing an S-shaped +40° angle sweep main pulse and >1 σ departures from OPTIMA optical both pulses, suggesting different radiation mechanisms or sites for polarized emission at two wavebands. Our map inner nebula reveals toroidal magnetic...