THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS
THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS
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DOI：
10.1088/0004-637x/713/1/154
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
A. Abdo;et al.
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文献类型：
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作者：
A. Abdo;et al.
我们报告的时间和光谱的船帆座脉冲星使用11个月的观测与大面积望远镜（LAT）的费米伽马射线太空望远镜的分析。船帆座在GeV的能量结合角分辨率和灵敏度的LAT的固有亮度，使我们能够进行最详细的研究，迄今为止的能量依赖的光变曲线和相位分辨光谱，使用LAT衍生的定时模型。光变曲线由两个峰（P1和P2）组成，这两个峰通过包含第三峰（P3）的桥发射连接。我们已经证实了强烈的P1/P2的比例与EGRET和以前的费米LAT数据看到的能量增加，并观察到P1消失超过20 GeV。P3分量的平均相位随能量的增加可以被更详细地跟踪，表明P3和P2存在直到脉动的最高能量。我们发现显着的脉冲发射的主要轮廓以外的阶段，表明磁层发射存在超过80%的脉冲星周期。随着高能量计数的增加，相位平均谱被认为偏离具有简单指数截止的幂律，并且更好地适合于更渐进的截止。固定计数相位仓中的光谱与指数截止的幂律很好地拟合，揭示了截止能量的强而复杂的相位依赖性，特别是在峰值处。通过将这些结果与将发射特性映射到相位的外磁层模型的预测相结合，将有可能以前所未有的细节探测粒子加速度和脉冲星磁层的结构。
We report on analysis of timing and spectroscopy of the Vela pulsar using 11 months of observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. The intrinsic brightness of Vela at GeV energies combined with the angular resolution and sensitivity of the LAT allows us to make the most detailed study to date of the energy-dependent light curves and phase-resolved spectra, using a LAT-derived timing model. The light curve consists of two peaks (P1 and P2) connected by bridge emission containing a third peak (P3). We have confirmed the strong decrease of the P1/P2 ratio with increasing energy seen with EGRET and previous Fermi LAT data, and observe that P1 disappears above 20 GeV. The increase with energy of the mean phase of the P3 component can be followed with much greater detail, showing that P3 and P2 are present up to the highest energies of pulsation. We find significant pulsed emission at phases outside the main profile, indicating that magnetospheric emission exists over 80% of the pulsar period. With increased high-energy counts the phase-averaged spectrum is seen to depart from a power law with simple exponential cutoff, and is better fit with a more gradual cutoff. The spectra in fixed-count phase bins are well fit with power laws with exponential cutoffs, revealing a strong and complex phase dependence of the cutoff energy, especially in the peaks. By combining these results with predictions of the outer magnetosphere models that map emission characteristics to phase, it will be possible to probe the particle acceleration and the structure of the pulsar magnetosphere with unprecedented detail.