MeerKAT脉冲星计时阵列中的时间相关轮廓变异性
Time-Correlated Profile Variability in the MeerKAT Pulsar Timing Array
- The University of Manchester（曼彻斯特大学）
- Swinburne University of Technology（斯威本科技大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用二维高斯过程框架分析MeerKAT六年数据，在84颗毫秒脉冲星中探测到18颗的轮廓变异性，推断至少40%的毫秒脉冲星存在内在变异性，并建议在未来计时实验中显式建模。
AI中文摘要：
长期脉冲轮廓变异性已成为高精度脉冲星计时潜在的重要不确定性来源，因为积分脉冲形状的变化可能偏置脉冲到达时间，并影响脉冲星计时阵列对纳赫兹引力波的灵敏度。我们对六年期MeerKAT脉冲星计时阵列数据进行了系统性搜索，以寻找长期脉冲轮廓变异性，使用二维高斯过程框架分析了84颗毫秒脉冲星的观测数据，以识别相干的时间和相位相关的轮廓演化。我们在18颗脉冲星中探测到了脉冲轮廓变异性。利用观测到的轮廓演化的频率依赖性以及散射模拟，我们将六颗脉冲星分类为表现出与星际散射一致的色散变异性，而其余十二颗则表现出主要为频率无关的行为，暗示脉冲星发射过程的内在变化。在修正了信噪比依赖的探测偏差后，我们推断内在轮廓变异性比探测样本所暗示的要普遍得多，至少有40%的毫秒脉冲星在95%可信水平上表现出内在轮廓变异性。受典型脉冲星中脉冲轮廓变异性与自转减慢率（$\dot{\nu}$）切换之间关联的启发，我们搜索了相应的$\dot{\nu}$变化，但未发现统计学上显著的探测。模拟表明，预期的变化仍低于当前数据集的灵敏度，尽管未解决的变化可能有助于产生微弱的消色散计时噪声。这些结果表明，长期脉冲轮廓变异性在毫秒脉冲星中可能很常见，应在未来的高精度脉冲星计时实验中明确建模。
英文摘要：
Long-term pulse-profile variability has emerged as a potentially important source of uncertainty for high-precision pulsar timing, as changes in the integrated pulse shape can bias pulse times of arrival and affect the sensitivity of pulsar timing arrays to nanohertz gravitational waves. We present a systematic search for long-term pulse-profile variability in the six-year MeerKAT Pulsar Timing Array data, analysing observations of 84 millisecond pulsars using a two-dimensional Gaussian-process framework to identify coherent temporal and phase-dependent profile evolution. We detect pulse-profile variability in 18 pulsars. Using the frequency dependence of the observed profile evolution together with scattering simulations, we classify six pulsars as exhibiting chromatic variability consistent with interstellar scattering, while the remaining twelve display predominantly frequency-independent behaviour suggestive of intrinsic changes in the pulsar emission process. Correcting for the S/N-dependent detection bias, we infer that intrinsic profile variability is substantially more common than implied by the detected sample, with at least 40 per cent of millisecond pulsars exhibiting intrinsic profile variability at the 95 per cent credible level. Motivated by the association between pulse-profile variability and spin-down-rate ($\dotν$) switching in canonical pulsars, we search for corresponding $\dotν$ variations but find no statistically significant detections. Simulations indicate that the expected variations remain below the sensitivity of current datasets, although unresolved changes may contribute to weak achromatic timing noise. These results suggest that long-term pulse-profile variability may be common among millisecond pulsars and should be explicitly modelled in future high-precision pulsar-timing experiments.
