利用MWA VCS数据对银河系平面进行成像脉冲星普查
Imaging pulsar census of the Galactic Plane using MWA VCS data
AI总结：
本文利用MWA高时间分辨率数据生成1秒全Stokes图像，对银河系平面开展低频图像域脉冲星普查，探测到83颗已知脉冲星，其中14颗为首次低频探测，证明了图像搜索方法在低频散射和色散致模糊条件下的独特优势。
摘要：
传统脉冲星巡天主要采用时域周期性搜索。然而，这些方法容易受到散射、掩食和轨道运动等效应的影响。在较低射电频率（≤300 MHz）下，色散量和脉冲展宽等因素变得更加显著，从而降低了探测灵敏度。另一方面，图像域脉冲星搜索不受这些效应限制，可以将参数空间扩展到传统搜索技术无法触及的区域。因此，我们开发了一条流水线，利用默奇森宽场阵列（Murchison Widefield Array，MWA）离线相关的高时间分辨率数据生成1秒全Stokes图像。这推动了基于图像的方法学发展，以识别新的脉冲星候选体。在本文中，我们应用这些方法学对银河系平面进行了低频基于图像的脉冲星普查（12次MWA观测，覆盖约6000平方度天区）。本工作重点是利用基于图像和波束形成两种方法，探测位于观测天区内已知脉冲星种群。结果共探测到83颗已知脉冲星，其中16颗脉冲星仅在Stokes I图像中被发现，而在波束形成数据的周期性搜索中未被发现。值得注意的是，其中14颗脉冲星是首次报道的低频探测结果。这强调了基于图像的搜索对于可能因低频散射和/或色散致模糊而在时间序列数据中无法探测到的脉冲星的重要性。这也突显了低频流量密度测量在完善脉冲星谱模型和研究脉冲星低频谱翻转方面的重要意义。
英文摘要：
Traditional pulsar surveys have primarily employed time-domain periodicity searches. However, these methods are susceptible to effects like scattering, eclipses and orbital motion. At lower radio frequencies (<= 300 MHz), factors such as dispersion measure and pulse broadening become more prominent, reducing the detection sensitivity. On the other hand, image domain searches for pulsars are not limited by these effects and can extend the parameter space to regions inaccessible to traditional search techniques. Therefore, we have developed a pipeline to form 1-second full Stokes images from offline correlated high time-resolution data from the Murchison Widefield Array (MWA). This led to the development of image-based methodologies to identify new pulsar candidates. In this paper, we applied these methodologies to perform a low-frequency image-based pulsar census of the Galactic Plane ( 12 MWA observations, covering ~6000 deg^2 sky ). This work focuses on the detection of the known pulsar population which were present in the observed region of the sky using both image-based and beamformed methods. This resulted in the detection of 83 known pulsars, with 16 pulsars found only in Stokes I images but not in periodicity searches applied in beamformed data. Notably, for 14 pulsars these are the first reported low-frequency detections. This underscores the importance of image-based searches for pulsars that may be undetectable in time-series data, due to scattering and/or dispersive smearing at low frequencies. This highlights the importance of low-frequency flux density measurements in refining pulsar spectral models and investigating the spectral turnover of pulsars at low frequencies.
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