利用高斯分量建模减轻PSR J1713+0747中异常脉冲轮廓形状变化的定时影响
Mitigating the Timing Impact of Anomalous Pulse Profile Shape Variability in PSR J1713+0747 with Gaussian Component Modeling
AI总结：
研究针对PSR J1713+0747脉冲形状异常变化影响计时稳定性问题，应用频率相关高斯分量模型分解脉冲轮廓，追踪分量演化，实现相位连接计时，恢复的TOAs不确定性与传统匹配相当，为相关计时方法发展迈出初步步伐。
AI中文摘要：
北美纳赫兹引力波天文台（NANOGrav）在其脉冲星计时阵列（PTA）中，对几颗毫秒脉冲星实现了亚微秒级的计时精度，目标是探测和表征纳赫兹引力波。PSR J1713+0747是该阵列中计时最精确脉冲星之一。然而在2021年4月，其脉冲形状突然异常变化，破坏了计时稳定性。由于它对PTA灵敏度有重要贡献，脉冲轮廓变化显著影响阵列对纳赫兹引力波的灵敏度。我们应用频率相关的高斯分量模型分解脉冲轮廓，并追踪各分量在事件中的演化。这种分量级方法在形状变化事件中保持相位连接计时。在L波段，恢复的到达时间（TOAs）中值不确定性约为0.47微秒，而标准模板匹配为0.69微秒。在820MHz处，轮廓演化更强，恢复的TOAs中值不确定性约为1.63微秒，标准模板匹配为0.67微秒。恢复的TOAs实现的计时不确定性与传统模板匹配相当，同时允许受轮廓变化影响的数据保留在PTA引力波分析中。这些结果是迈向能够考虑脉冲轮廓演化同时减少对额外计时模型参数需求的轮廓域计时方法的初步步骤。
英文摘要：
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) achieves sub-microsecond timing precision for several millisecond pulsars in its pulsar timing array (PTA) with the objective of detecting and characterizing nanohertz gravitational waves. PSR J1713+0747 is one of the most precisely timed pulsars in the array, achieving sub-microsecond timing precision. However, in April 2021, PSR J1713+0747 underwent a sudden and unusual change in pulse shape that disrupted its timing stability. As PSR J1713+0747 is a key contributor to PTA sensitivity, variations in its pulse profile significantly affect the array's sensitivity to nanohertz gravitational waves. We apply frequency-dependent Gaussian component models to decompose the pulse profile and track the evolution of individual components through the event. This component-level method maintains phase-connected timing across the shape-change event. At L-band, the recovered TOAs have a median uncertainty of ~0.47 microseconds compared to ~0.69 microseconds for standard template matching. At 820 MHz, where profile evolution is stronger, the recovered TOAs have a median uncertainty of ~1.63 microseconds compared to ~0.67 microseconds for standard template matching. The recovered TOAs achieve timing uncertainties comparable to conventional template matching while allowing data affected by profile variability to be retained in PTA gravitational-wave analyses. These results represent an initial step toward profile-domain timing methods capable of accounting for pulse-profile evolution while reducing the need for additional timing model parameters.
