We search through $\gamma$-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope and find 24 blazars (or candidates) that have a single clear flare event in their 9.5 year long-term light curves. We define these events as loner flares since each flare stands out significantly above the relatively stable, low-flux light curve. We analyze the LAT data in detail for these 24 sources. The flares in ten of them are primarily due to a single sharp peak, for which we study by fitting with two different analytic functions. The time durations thus determined for the sharp peaks are in a range of 4-25 days. The $\gamma$-ray spectra of the 24 blazar sources can be described with a power-law or a log-parabola function. We obtain their spectral properties in the flaring and quiescent states, and find that in the flares 16 of the sources have harder emission and three have softer emission while the other five keep the same emission. We discuss a possible correlation between the differences in photon index in the quiescent and flaring states and photon indices in quiescence. In addition, the sharp peak flares seem to have a tendency of having long time durations and hard emission, possibly related to their physical origin in a blazar jet. Studies of more similar flares will help establish these possible features.

中文翻译：

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伽马射线耀变体“孤独”耀斑的特性研究

我们搜索了费米伽马射线太空望远镜上的大面积望远镜 (LAT) 获得的 $\gamma$ 射线数据，并找到了 24 个耀变体（或候选者），它们在其 9.5 年的长期光中具有单一的清晰耀斑事件曲线。我们将这些事件定义为孤独的耀斑，因为每个耀斑都显着高于相对稳定的低通量光曲线。我们详细分析了这 24 个来源的 LAT 数据。其中 10 个中的耀斑主要是由于单个尖峰造成的，我们通过拟合两个不同的分析函数来研究它。如此确定的尖峰持续时间在 4-25 天的范围内。24 个耀变体源的 $\gamma$ 射线光谱可以用幂律或对数抛物线函数来描述。我们获得了它们在燃烧和静止状态下的光谱特性，并发现在耀斑中，16个源的发射较硬，3个发射较软，其余5个保持相同的发射。我们讨论了静止和爆发状态下的光子指数差异与静止状态下的光子指数之间可能存在的相关性。此外，尖锐的峰值耀斑似乎具有持续时间长和发射强度大的趋势，这可能与它们在耀变体喷流中的物理起源有关。对更多类似耀斑的研究将有助于确定这些可能的特征。尖锐的峰值耀斑似乎具有持续时间长和发射强度高的趋势，这可能与它们在耀变体喷流中的物理起源有关。对更多类似耀斑的研究将有助于确定这些可能的特征。尖锐的峰值耀斑似乎具有持续时间长和发射强度高的趋势，这可能与它们在耀变体喷流中的物理起源有关。对更多类似耀斑的研究将有助于确定这些可能的特征。