Scattering Study of Pulsars below 100 MHz Using LWA1
Scattering Study of Pulsars below 100 MHz Using LWA1
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DOI：
10.3847/1538-4357/ab0d8f
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
K. Bansal;G. Taylor;K. Stovall;J. Dowell
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文献类型：
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作者：
K. Bansal;G. Taylor;K. Stovall;J. Dowell
星际散射导致脉冲星轮廓不对称地增长，从而影响脉冲星定时残差，并且在较低频率下最强。不同的星际介质模型预测散射时间尺度τsc的不同频率（ν）和色散测度（DM）依赖性。对于高斯不均匀性，预期的比例关系为，而对于不规则的柯尔莫哥洛夫分布，预期的关系为。以前的散射研究表明，在所有范围的DM的散射指数范围很广。低于4的散射指数被认为是由于薄屏模型的基本假设的限制或各向异性散射机制。我们提出了一个散射的研究7个附近的恒星（DM < 50 pc cm−3）在低频率（10-88 MHz），使用长波长阵列的第一站。我们研究的散射光谱指数和DM的变化在一个为期约三年。结果产生洞察星际介质的小尺度结构，以及低DM恒星的薄屏幕模型的适用性。
Interstellar scattering causes pulsar profiles to grow asymmetrically, thus affecting the pulsar timing residuals, and is strongest at lower frequencies. Different interstellar medium models predict different frequency (ν) and dispersion measure (DM) dependencies for the scattering timescale τsc. For Gaussian inhomogeneity the expected scaling relation is , while for a Kolmogorov distribution of irregularities, the expected relation is . Previous scattering studies showed a wide range of scattering index across all ranges of DM. A scattering index below 4 is believed to be either due to limitations of the underlying assumptions of the thin-screen model or an anisotropic scattering mechanism. We present a study of scattering for seven nearby pulsars (DM < 50 pc cm−3) observed at low frequencies (10–88 MHz), using the first station of the Long Wavelength Array. We examine the scattering spectral index and DM variation over a period of about three years. The results yield insights into the small-scale structure of the interstellar medium, as well as the applicability of the thin-screen model for low-DM pulsars.