The Fast Radio Burst Luminosity Function and Death Line in the Low-twist Magnetar Model
The Fast Radio Burst Luminosity Function and Death Line in the Low-twist Magnetar Model
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DOI：
10.3847/1538-4357/ab6d69
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
Z. Wadiasingh;P. Beniamini;A. Timokhin;M. Baring;A. J. van der Horst;A. Harding;D. Kazanas
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文献类型：
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作者：
Z. Wadiasingh;P. Beniamini;A. Timokhin;M. Baring;A. J. van der Horst;A. Harding;D. Kazanas
在WT19低扭磁星模型中，研究了快速射电暴（frb）的能量分布。基于FRB 121102的幂律影响分布，我们提出了单个中继器FRB亮度函数的基本模型，该模型采用反演协议，将磁星短暴影响的幂律分布指数与FRB的幂律分布指数直接联系起来。该方案表明，如果磁星短爆发在磁弹性体系中占上风，那么快速射电暴能量几乎与地壳/场位错幅度成线性关系。单个中继器在爆发期间磁层中的电荷饥饿（WT19要求）意味着预测的爆发通量分布很窄，在屈服应变和磁星地壳中可行的振荡频率上小于30年。需要磁约束和电荷饥饿，我们获得了快速射电暴的死亡线，它将磁星与正常脉冲星群分开，表明只有前者会经常发生快速射电暴。我们对单个磁星的爆发能量分布进行卷积，以确定演化磁星群中光度的分布。破幂律光度函数的低能特征取决于种群模型，而高能指数则跟踪单个中继器的低能特征。与进化种群无关，破缺的幂律各向同性等效能量/光度函数在~ 1037 - 1040 erg处达到峰值，在~ 1037 erg处达到低能量截止。最后，我们考虑了快速射电暴的局部通量分布，并发现它可以约束产生快速射电暴的磁星祖星子集。我们的模型表明，灵敏度的提高可能揭示出全球快速射电暴影响分布的平坦化和快速射电暴率的饱和。
We explore the burst energy distribution of fast radio bursts (FRBs) in the low-twist magnetar model of Wadiasingh & Timokhin (WT19). Motivated by the power-law fluence distributions of FRB 121102, we propose an elementary model for the FRB luminosity function of individual repeaters with an inversion protocol that directly relates the power-law distribution index of magnetar short burst fluences to that for FRBs. The protocol indicates that the FRB energy scales virtually linearly with crust/field dislocation amplitude, if magnetar short bursts prevail in the magnetoelastic regime. Charge starvation in the magnetosphere during bursts (required in WT19) for individual repeaters implies the predicted burst fluence distribution is narrow, ≲3 decades for yielding strains and oscillation frequencies feasible in magnetar crusts. Requiring magnetic confinement and charge starvation, we obtain a death line for FRBs, which segregates magnetars from the normal pulsar population, suggesting only the former will host recurrent FRBs. We convolve the burst energy distribution for individual magnetars to define the distribution of luminosities in evolved magnetar populations. The broken power-law luminosity function’s low-energy character depends on the population model, while the high-energy index traces that of individual repeaters. Independent of the evolved population, the broken power-law isotropic-equivalent energy/luminosity function peaks at ∼1037–1040 erg with a low-energy cutoff at ∼1037 erg. Lastly, we consider the local fluence distribution of FRBs and find that it can constrain the subset of FRB-producing magnetar progenitors. Our model suggests that improvements in sensitivity may reveal a flattening of the global FRB fluence distribution and saturation in FRB rates.