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arXiv 1309.1982astro-ph.SRastro-ph.HE
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非回收费米脉冲星群的建模gamma-ray

Modeling the non-recycled Fermi gamma-ray pulsar population

B. B. P. Perera, M. A. McLaughlin, J. M. Cordes, M. Kerr, T. H. Burnett, A. K. Harding

备注：
26 pages, 10 figures, Accepted by ApJ on 8 September 2013
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摘要：

我们使用费米伽玛射线空间望远镜的探测和上限的非回收的大面积望远镜（LAT）获得的恒星约束伽玛射线光度L如何依赖于周期P和周期导数\dot{P}。我们使用贝叶斯分析来计算最佳拟合光度定律，或L对P和\dot{P}的依赖性，包括用于建模聚束因子的不同方法。外间隙（OG）磁层几何形状提供了最佳拟合模型，它是L \propto P^{-a} \dot{P}^{b}，其中a=1.36 \pm 0.03，b=0.44 \pm 0.02，与通常假设的L \propto \sqrt{\dot{E}} \propto P^{-1.5} \dot{P}^{0.5}相似但不完全相同。鉴于目前已知的射电望远镜的伽马射线通量的上限，并使用OG模型，我们发现，大约92%的无线电探测到的射电望远镜有伽马射线束，我们的视线相交。通过模拟这些恒星的射电和伽马射线束的不对准，我们发现OG模型的平均伽马射线束射立体角约为3.7π，假设光束均匀。使用LAT测量的扩散通量，我们将脉冲星群体的平均制动指数和平均表面磁场强度分别设为2σ上限和2σ下限，分别为3.8和3.2 X 10^{10} G。然后，我们根据我们的人口模型预测LAT可检测到的非回收垃圾的数量。使用两年的灵敏度，我们发现，LAT是能够检测到约380个非回收的辐射源，包括150个目前确定的无线电辐射源。使用预期的五年灵敏度，大约620个非回收的卫星是可检测的，包括大约220个目前确定的无线电卫星。我们注意到，这些预测在很大程度上取决于我们的模型假设。

英文摘要：

We use Fermi Gamma-ray Space Telescope detections and upper limits on non-recycled pulsars obtained from the Large Area Telescope (LAT) to constrain how the gamma-ray luminosity L depends on the period P and the period derivative \dot{P}. We use a Bayesian analysis to calculate a best-fit luminosity law, or dependence of L on P and \dot{P}, including different methods for modeling the beaming factor. An outer gap (OG) magnetosphere geometry provides the best-fit model, which is L \propto P^{-a} \dot{P}^{b} where a=1.36\pm0.03 and b=0.44\pm0.02, similar to but not identical to the commonly assumed L \propto \sqrt{\dot{E}} \propto P^{-1.5} \dot{P}^{0.5}. Given upper limits on gamma-ray fluxes of currently known radio pulsars and using the OG model, we find that about 92% of the radio-detected pulsars have gamma-ray beams that intersect our line of sight. By modeling the misalignment of radio and gamma-ray beams of these pulsars, we find an average gamma-ray beaming solid angle of about 3.7π for the OG model, assuming a uniform beam. Using LAT-measured diffuse fluxes, we place a 2σ upper limit on the average braking index and a 2σ lower limit on the average surface magnetic field strength of the pulsar population of 3.8 and 3.2 X 10^{10} G, respectively. We then predict the number of non-recycled pulsars detectable by the LAT based on our population model. Using the two-year sensitivity, we find that the LAT is capable of detecting emission from about 380 non-recycled pulsars, including 150 currently identified radio pulsars. Using the expected five-year sensitivity, about 620 non-recycled pulsars are detectable, including about 220 currently identified radio pulsars. We note that these predictions significantly depend on our model assumptions.

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