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arXiv 1502.06785astro-ph.HEastro-ph.SR
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PSR J1022 +1001的单脉冲和曲线变异性研究

Single pulse and profile variability study of PSR J1022+1001

K. Liu, R. Karuppusamy, K. J. Lee, B. W. Stappers, M. Kramer, R. Smits, M. B. Purver, G. H. Janssen, D. Perrodin

摘要:

毫秒钟是一种高稳定度的天体钟。然而,最近的研究表明,它们的综合脉冲轮廓的不稳定性,这可能会限制可实现的脉冲星定时精度。在本文中,我们提出了一个案例研究的脉冲轮廓变化的PSR J1022+1001。在35小时的观测中,我们已经探测到大约14,000个子脉冲(单脉冲的组成部分),大部分位于积分轮廓的拖尾部分。它们的通量密度和分数极化表明,它们代表了普通发射模式下能量分布的亮端,而不是巨脉冲。来自积分轮廓的前沿和尾部分量的子脉冲的出现被证明是相关的。对于后者的子脉冲,一个优选的脉冲宽度约为0.25 ms已被发现。使用同时观测从Effelsberg 100米望远镜和Westerbork综合射电望远镜,我们发现,综合的轮廓变化的时间尺度上的几十分钟。我们发现,不适当的偏振校准和衍射闪烁不能观察到的不稳定性的唯一原因。此外,我们证明,从检测到的子脉冲的平均值产生的定时残差占主导地位的相位抖动,并放置一个上限为~700 ns的抖动噪声的基础上连续1分钟的积分。

英文摘要:

Millisecond pulsars (MSPs) are known as highly stable celestial clocks. Nevertheless, recent studies have revealed the unstable nature of their integrated pulse profiles, which may limit the achievable pulsar timing precision. In this paper, we present a case study on the pulse profile variability of PSR J1022+1001. We have detected approximately 14,000 sub-pulses (components of single pulses) in 35-hr long observations, mostly located at the trailing component of the integrated profile. Their flux densities and fractional polarisation suggest that they represent the bright end of the energy distribution in ordinary emission mode and are not giant pulses. The occurrence of sub-pulses from the leading and trailing components of the integrated profile is shown to be correlated. For sub-pulses from the latter, a preferred pulse width of approximately 0.25 ms has been found. Using simultaneous observations from the Effelsberg 100-m telescope and the Westerbork Synthesis Radio Telescope, we have found that the integrated profile varies on a timescale of a few tens of minutes. We show that improper polarisation calibration and diffractive scintillation cannot be the sole reason for the observed instability. In addition, we demonstrate that timing residuals generated from averages of the detected sub-pulses are dominated by phase jitter, and place an upper limit of ~700 ns for jitter noise based on continuous 1-min integrations.

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