论文标题
从同期的宽波段观测值中检测到频率依赖性分散量测度
Detection of frequency-dependent dispersion measure toward the millisecond pulsar PSR J2241-5236 from contemporaneous wide-band observations
论文作者
论文摘要
对脉冲星分散措施（DMS）进行精确测量并为其应用合适的校正是高精度时序程序（例如脉冲星定时阵列（PTA））的主要挑战之一。虽然宽波 - 脉冲星的出现可以实现更精确的DM测量结果，并提高了时序精度，但它还需要对Cordes等人理论上仔细评估频率依赖性（色度）DMS。 （2016）。在这里，我们报告了对毫秒Pulsar PSR PSR J2241-5236的宽带观测的检测，这是当前和未来PTA的高优先级目标。这些观察是使用宽带接收器和现在在Murchison Widefield阵列（MWA），已升级的巨型巨人射线望远镜（UGMRT）和Parkes望远镜的宽带接收器和功能时期进行的，因此提供了前所未有的较大频率覆盖率，从80 MHz到4 GHz。我们的分析显示，观察频率（$ν$）的DM的可测量变化为$ \rmΔdm\simν^{2.5 \ pm 0.1} $。我们讨论了这种频率依赖性在测得的DM中的潜在含义，以及可能对定时噪声预算的可能影响，并评论低频观察在推进PTA努力中的有用性。
Making precise measurements of pulsar dispersion measures (DMs) and applying suitable corrections for them is amongst the major challenges in high-precision timing programmes such as pulsar timing arrays (PTAs). While the advent of wide-band pulsar instrumentation can enable more precise DM measurements and thence improved timing precision, it also necessitates doing careful assessments of frequency-dependent (chromatic) DMs that was theorised by Cordes et al. (2016). Here we report the detection of such an effect in broadband observations of the millisecond pulsar PSR J2241-5236, a high-priority target for current and future PTAs. The observations were made contemporaneously using the wide-band receivers and capabilities now available at the Murchison Widefield Array (MWA), the upgraded Giant Metrewave Radio Telescope (uGMRT) and the Parkes telescopes, thus providing an unprecedentedly large frequency coverage from 80 MHz to 4 GHz. Our analysis shows the measurable changes in DM that scale with the observing frequency ($ν$) as $\rm δDM \sim ν^{2.5 \pm 0.1}$. We discuss the potential implications of such a frequency dependence in the measured DMs, and the likely impact on the timing noise budget, and comment on the usefulness of low-frequency observations in advancing PTA efforts.
