FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR
FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE VELA PULSAR
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DOI：
10.1088/0004-637x/696/2/1084
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发表时间：
2008-12
期刊：
影响因子：
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通讯作者：
A. Abdo;et al.
中科院分区：
文献类型：
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作者：
A. Abdo;et al.
船帆座脉冲星是在GeV的天空中最明亮的持续源，因此是传统的第一个目标，新的伽马射线天文台。我们在这里报告的初步费米大天区望远镜观测验证阶段的指向曝光和早期的天空调查扫描。我们已经使用船帆座信号来验证费米定时和角分辨率。高质量的脉冲轮廓，在E>0.03 GeV时约有32，400个脉冲光子，显示出新的特征，包括精细至0.3ms的脉冲结构和明显的第三个峰，其相位随能量移动。我们研究了脉冲发射的高能行为，初始谱表明γ =1.51{+0.05/-0.04}的相位平均幂律指数，在E_c=2.9+/-0.1 GeV处有指数截止。用e^{-（E/E_c）^B}形式的广义截止值进行谱拟合要求B<1，这与磁对衰减不一致，因此有利于外磁层发射模型。最后，我们报告的上限，任何非脉冲成分，可能与周围的同步加速器风星云（PWN）。
The Vela pulsar is the brightest persistent source in the GeV sky and thus is the traditional first target for new gamma-ray observatories. We report here on initial Fermi Large Area Telescope observations during verification phase pointed exposure and early sky survey scanning. We have used the Vela signal to verify Fermi timing and angular resolution. The high quality pulse profile, with some 32,400 pulsed photons at E>0.03 GeV, shows new features, including pulse structure as fine as 0.3ms and a distinct third peak, which shifts in phase with energy. We examine the high energy behavior of the pulsed emission; initial spectra suggest a phase-averaged power law index of Gamma=1.51{+0.05/-0.04} with an exponential cut-off at E_c=2.9+/-0.1 GeV. Spectral fits with generalized cut-offs of the form e^{-(E/E_c)^b} require b<1, which is inconsistent with magnetic pair attenuation, and thus favor outer magnetosphere emission models. Finally, we report on upper limits to any unpulsed component, as might be associated with a surrounding synchrotron wind nebula (PWN).