Pulsar scintillation studies with LOFAR. I. The census
Pulsar scintillation studies with LOFAR. I. The census
复制标题
使用 LOFAR 进行脉冲星闪烁研究。
DOI：
10.1051/0004-6361/202142980
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
C. Vocks
中科院分区：
文献类型：
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作者：
Ziwei Wu;J. Verbiest;R. Main;J. Grießmeier;Yulan Liu;S. Osłowski;K. M. Ambalappat;A. B. Nielsen;J. Kunsemoller;J. Y. Donner;C. Tiburzi;N. Porayko;M. Serylak;L. Kunkel;M. Bruggen;C. Vocks
语境。脉冲星发射的星际闪烁（ISS）既可以用作电离星际介质（IISM）的探针，也可以导致脉冲星计时实验的损坏。特别令人感兴趣的是所谓的闪烁弧，它可用于直接测量随时间变化的星际散射延迟，从而有可能实现计时精度的高精度改进。目标。本研究的主要目的是对低频下的衍射脉冲星闪烁和闪烁弧可探测性进行首次大规模且自洽的普查，作为大规模 IISM 研究和使用低频阵列 (LOFAR) 高频带天线 (HBA) 进行脉冲星授时相关传播研究的基础。方法。我们使用来自五个国际 LOFAR 站和荷兰 LOFAR 核心的观测数据。我们分析这些观测的动态光谱的二维自协方差函数，以确定国际空间站对样本中脉冲星的特征带宽和时间尺度，并研究动态光谱的二维功率谱，以确定闪烁弧的存在。结果。在最初的 31 个源中，有 15 个可以完全测定闪烁特性；其中九个在 120–180MHz 处显示出可检测到的闪烁弧。观察到的八个源显示出未解决的闪烁；最后八个不显示衍射闪烁。尽管无法确定明确的截止值，但闪烁可探测性和脉冲星亮度以及色散测量之间的某些相关性是显而易见的。我们在大分数带宽上的测量允许对闪烁参数的频率缩放进行有意义的测试，而不受折射闪烁变化的影响。结论。我们的结果表明了国际空间站低频研究的强大优势和巨大潜力，以及闪烁可探测性对脉冲星亮度和星际色散等参数的复杂依赖性。这项工作提供了第一次大规模普查和对国际空间站低频影响的长期监测。它们的脉冲间歇特性的亚积分使得闪烁时标的确定变得复杂，闪烁带宽仍然可以使用标准方法来确定。
Context. Interstellar scintillation (ISS) of pulsar emission can be used both as a probe of the ionized interstellar medium (IISM) and cause corruptions in pulsar timing experiments. Of particular interest are so-called scintillation arcs which can be used to measure time-variable interstellar scattering delays directly, potentially allowing high-precision improvements to timing precision. Aims. The primary aim of this study is to carry out the first sizeable and self-consistent census of diffractive pulsar scintillation and scintillation-arc detectability at low frequencies, as a primer for larger-scale IISM studies and pulsar-timing related propagation studies with the LOw-Frequency ARray (LOFAR) High Band Antennae (HBA). Methods. We use observations from five international LOFAR stations and the LOFAR core in the Netherlands. We analyze the 2D auto-covariance function of the dynamic spectra of these observations to determine the characteristic bandwidth and timescale of the ISS toward the pulsars in our sample and investigate the 2D power spectra of the dynamic spectra to determine the presence of scintillation arcs. Results. In this initial set of 31 sources, 15 allow for the full determination of the scintillation properties; nine of these show detectable scintillation arcs at 120–180MHz. Eight of the observed sources show unresolved scintillation; and the final eight do not display diffractive scintillation. Some correlation between scintillation detectability and pulsar brightness and a dispersion measure is apparent, although no clear cut-off values can be determined. Our measurements across a large fractional bandwidth allow a meaningful test of the frequency scaling of scintillation parameters, uncorrupted by influences from refractive scintillation variations. Conclusions. Our results indicate the powerful advantage and great potential of ISS studies at low frequencies and the complex dependence of scintillation detectability on parameters such as pulsar brightness and interstellar dispersion. This work provides the first installment of a larger-scale census and longer-term monitoring of ISS effects at low frequencies. subintegration of pulse intermittent character of their makes the determination of the scintillation timescale complicated, the scintillation bandwidth can still be determined using standard methods.