论文标题
检测重复FRB 180916.J0158+65降低到300 MHz的频率
Detection of Repeating FRB 180916.J0158+65 Down to Frequencies of 300 MHz
论文作者
论文摘要
我们报告了从定期活跃的，重复快速无线电爆发（FRB）FRB 180916.J0158+65中检测到的七次突发，在300-400-MHz频率范围内，绿色银行望远镜（GBT）。可见到GBT频段底部的多个爆发中的发射，这表明FRB发射的截止频率（如果存在）低于300 MHz。观察在预测的源活动期间进行了观测，并在加拿大氢强度映射实验（Chime）望远镜上同时覆盖了低频阵列（Lofar）和FRB后端。我们发现，GBT检测的爆发之一具有潜在的相关发射（400-800 MHz），但我们发现Lofar频段（110-190 MHz）中没有爆发，在宽带发射频谱上的光谱上的限制限制为$α> -1.0 $。我们还发现，来自源的发射是严格的带宽，低至$ \ sim $ 40 MHz。此外，我们对源可观察到的散射（$ 1.7毫秒，350 MHz）放置了最严格的限制，这表明Circumburst环境没有强大的散射特性。此外，知道Circumburst环境在300 MHz时在光学上是光学薄到免费的吸收，我们发现了反对超紧凑型HII区域或年轻的超新星残留物（年龄$ <$ 50的年龄）与来源的相关性的证据。
We report on the detection of seven bursts from the periodically active, repeating fast radio burst (FRB) source FRB 180916.J0158+65 in the 300-400-MHz frequency range with the Green Bank Telescope (GBT). Emission in multiple bursts is visible down to the bottom of the GBT band, suggesting that the cutoff frequency (if it exists) for FRB emission is lower than 300 MHz. Observations were conducted during predicted periods of activity of the source, and had simultaneous coverage with the Low Frequency Array (LOFAR) and the FRB backend on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope. We find that one of the GBT-detected bursts has potentially associated emission in the CHIME band (400-800 MHz) but we detect no bursts in the LOFAR band (110-190 MHz), placing a limit of $α> -1.0$ on the spectral index of broadband emission from the source. We also find that emission from the source is severely band-limited with burst bandwidths as low as $\sim$40 MHz. In addition, we place the strictest constraint on observable scattering of the source, $<$ 1.7 ms, at 350 MHz, suggesting that the circumburst environment does not have strong scattering properties. Additionally, knowing that the circumburst environment is optically thin to free-free absorption at 300 MHz, we find evidence against the association of a hyper-compact HII region or a young supernova remnant (age $<$ 50 yr) with the source.
