FERMI/LAT OBSERVATIONS OF LS 5039
FERMI/LAT OBSERVATIONS OF LS 5039
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DOI：
10.1088/0004-637x/706/1/l56
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发表时间：
2009-10
期刊：
影响因子：
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通讯作者：
A. Abdo;M. Ackermann;M. Ajello;W. Atwood;M. Axelsson;L. Baldini;J. Ballet;G. Barbiellini;
中科院分区：
文献类型：
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作者：
A. Abdo;M. Ackermann;M. Ajello;W. Atwood;M. Axelsson;L. Baldini;J. Ballet;G. Barbiellini;
提出了使用费米伽马射线太空望远镜数据在 2008 年 8 月至 2009 年 6 月期间对高质量 X 射线双星 LS 5039 进行观测的第一个结果。我们的结果表明变异性与二元周期一致，发射周期为 3.903 ± 0.005 天；首次在 GeV 能量下检测到这种调制。光变曲线的特征是上合点附近有一个宽峰，与逆康普顿散射模型一致。光谱由指数截止的幂律表示，产生 4.9 ± 0.5(stat) ± 1.8(syst) ×10−7 photon cm−2 s−1 的总通量 (100 MeV–300 GeV)，截止值为 2.1 ± 0.3(stat) ± 1.1(syst) GeV 和光子指数 Γ = 1.9 ± 0.1(stat) ± 0.3（系统）。观察到光谱随轨道相位变化，特别是在下合和上合之间。我们认为光谱中截止的存在可能表明磁层发射类似于费米在许多脉冲星中看到的发射。
The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 ± 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV–300 GeV) of 4.9 ± 0.5(stat) ± 1.8(syst) ×10−7 photon cm−2 s−1, with a cutoff at 2.1 ± 0.3(stat) ± 1.1(syst) GeV and photon index Γ = 1.9 ± 0.1(stat) ± 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.