标题： 所有快速射电暴都会重复吗？ 来自CHIME/FRB远侧瓣快速射电暴的限制 显示英文标题

标题： Do All Fast Radio Bursts Repeat? Constraints from CHIME/FRB Far Side-Lobe FRBs

摘要： 我们报告了加拿大氢强度测绘实验（CHIME）在远侧瓣区域（即，$\geq 5^\circ$离轴）检测到的十个快速射电暴（FRB），时间范围从2018年8月28日至2021年8月31日。我们通过拟合这些射电暴的光谱与CHIME/FRB综合波束响应模型来定位它们。我们发现，远侧瓣事件的平均流量比在CHIME主瓣中检测到的事件大约高500倍。因此，我们表明侧瓣样本在统计上比主瓣样本近约20倍。我们在距离分别为38和16百万秒差距处找到了两个FRB（20190112B和20210310B）的可能宿主星系候选者（P$_{\rm cc}$ < 1%）。在总计35580小时的观测时间内，CHIME/FRB未观察到来自10个侧瓣FRB均匀样本中具有相似亮度的重复现象。假设爆发是泊松分布的，我们推断远侧瓣事件在高于检测阈值以上的平均重复间隔大于11880小时，这至少是已知CHIME/FRB检测到的重复源间隔的2380倍，但需要注意的是，可能存在一些窄带事件被遗漏的情况。这些远侧瓣事件的结果暗示了两种情况之一：要么（1）所有FRB都会重复，并且重复间隔范围很广，高重复率的子群体非常稀少；要么（2）非重复FRB是一个不同于已知重复源的独立群体。 显示英文摘要

摘要： We report ten fast radio bursts (FRBs) detected in the far side-lobe region (i.e., $\geq 5^\circ$ off-meridian) of the Canadian Hydrogen Intensity Mapping Experiment (CHIME) from 2018 August 28 to 2021 August 31. We localize the bursts by fitting their spectra with a model of the CHIME/FRB synthesized beam response. We find that the far side-lobe events have on average ~500 times greater fluxes than events detected in CHIME's main lobe. We show that the side-lobe sample is therefore statistically ~20 times closer than the main-lobe sample. We find promising host galaxy candidates (P$_{\rm cc}$ < 1%) for two of the FRBs, 20190112B and 20210310B, at distances of 38 and 16 Mpc, respectively. CHIME/FRB did not observe repetition of similar brightness from the uniform sample of 10 side-lobe FRBs in a total exposure time of 35580 hours. Under the assumption of Poisson-distributed bursts, we infer that the mean repetition interval above the detection threshold of the far side-lobe events is longer than 11880 hours, which is at least 2380 times larger than the interval from known CHIME/FRB detected repeating sources, with some caveats, notably that very narrow-band events could have been missed. Our results from these far side-lobe events suggest one of two scenarios: either (1) all FRBs repeat and the repetition intervals span a wide range, with high-rate repeaters being a rare subpopulation, or (2) non-repeating FRBs are a distinct population different from known repeaters.