Limits on fast radio bursts at 145 MHz with artemis, a real-time software backend
Limits on fast radio bursts at 145 MHz with artemis, a real-time software backend
复制标题
使用实时软件后端 artemis 对 145 MHz 的快速无线电突发进行限制
DOI：
10.1093/mnras/stv1306
复制
发表时间：
2015
影响因子：
4.8
通讯作者：
Karastergiou A
中科院分区：
文献类型：
--
作者：
Karastergiou A
快速射电暴（FRB）是毫秒级的无线电信号，其色散大于银河系电子密度所能解释的。我们在145 MHz频率上对FRB进行了1446 h的观测，共覆盖了4193 deg 2的天空。我们使用低频阵列射电望远镜的英国站-罗林斯阵列-大部分时间都与位于南赛的低频阵列站一起，以相同的频率观测相同的场。我们的实时搜索后端，高级无线电瞬态事件监测和识别系统-artemis，利用图形处理单元搜索色散测量高达320 cm− 3 pc的脉冲。以前从1.4 GHz左右的调查中得出的FRB率，以及FRB的有利解释，激发了这次调查，尽管以前所有的检测都发生在更高的色散措施。我们没有检测到超过信噪比阈值10的新FRB，这导致了这些频率下FRB事件率的最严格上限：对于超过62 Jy的5 ms持续时间脉冲，29 sky−1d− 1。未检测到可能是由于散射增宽，体积和时间的限制搜索，或FRB通量密度谱的形状。假设FRB是标准烛光，如果它们的光谱遵循与频率（α να）的幂律，α ν α +0.1，表明与脉冲星光谱有显著差异，则未检测到FRB与已公布的FRB天空速率是一致的。我们的研究结果表明，在更高的频率，包括平方公里阵列的低频分量的调查，将有更好的机会来检测，估计率和了解FRB的起源和属性。
Fast radio bursts (FRBs) are millisecond radio signals that exhibit dispersion larger than what the Galactic electron density can account for. We have conducted a 1446 h survey for FRBs at 145 MHz, covering a total of 4193 deg2on the sky. We used the UK station of the low frequency array (LOFAR) radio telescope – the Rawlings Array – accompanied for a majority of the time by the LOFAR station at Nançay, observing the same fields at the same frequency. Our real-time search backend, Advanced Radio Transient Event Monitor and Identification System –artemis, utilizes graphics processing units to search for pulses with dispersion measures up to 320 cm−3pc. Previous derived FRB rates from surveys around 1.4 GHz, and favoured FRB interpretations, motivated this survey, despite all previous detections occurring at higher dispersion measures. We detected no new FRBs above a signal-to-noise threshold of 10, leading to the most stringent upper limit yet on the FRB event rate at these frequencies: 29 sky−1d−1for five ms-duration pulses above 62 Jy. The non-detection could be due to scatter-broadening, limitations on the volume and time searched, or the shape of FRB flux density spectra. Assuming the latter and that FRBs are standard candles, the non-detection is compatible with the published FRB sky rate, if their spectra follow a power law with frequency (∝ να), with α ≳ +0.1, demonstrating a marked difference from pulsar spectra. Our results suggest that surveys at higher frequencies, including the low frequency component of the Square Kilometre Array, will have better chances to detect, estimate rates and understand the origin and properties of FRBs.