Fermi Large Area Telescope observations of the fast-dimming Crab Nebula in 60–600 MeV
Fermi Large Area Telescope observations of the fast-dimming Crab Nebula in 60–600 MeV
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费米大面积望远镜对 60â600 MeV 快速变暗的蟹状星云的观测
DOI：
10.1051/0004-6361/201936740
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发表时间：
2020
影响因子：
6.5
通讯作者：
Paul K.H.
中科院分区：
文献类型：
--
作者：
Paul K.H.
蟹状脉冲星及其星云是相对论性电子的起源，通过同步加速器和逆康普顿发射可以观测到相对论性电子。同步加速器主导和逆康普顿主导之间的转变发生在≈109eV。目的利用费米大面积望远镜在60兆电子伏特至600兆电子伏特的10年观测数据，研究高能电子同步辐射的短期（持续一周至数月）通量变化。方法利用相位分辨数据重建非脉冲光曲线。使用相应的通量测量直方图来识别通量状态的分布，并通过模拟光曲线的专门模拟来估计低通量分量的统计显著性。重建了不同通量状态下的能谱。结果证实了燃烧态的存在，燃烧态遵循对数正态通量分布。此外，我们还发现了一个低通量状态，其中通量降至中间状态平均通量的18.4%，并持续数周。据观察，过渡时间短至两天。在低通量状态下的能谱类似于在超过几个GeV能量的能量下测量的逆康普顿能谱的外推，这意味着同步加速器发射的高能部分被显著抑制。结论低通量态和最多10天的跃迁时间表明，108eV以上同步辐射的大部分（>75%）来自视角尺寸为θ≈0″的致密体。4 tvar / (5 d)。我们初步推断，所谓的内结特征是大部分γ射线发射的来源。
ContextThe Crab pulsar and its nebula are the origin of relativistic electrons which can be observed through their synchrotron and inverse Compton emission. The transition between synchrotron-dominated and inverse-Compton-dominated emissions takes place at ≈109eV.AimsThe short-term (lasting for one week to months) flux variability of the synchrotron emission from the most energetic electrons is investigated with data from ten years of observations with theFermiLarge Area Telescope in the energy range from 60 MeV to 600 MeV.MethodsWe reconstructed the off-pulse light curve reconstructed from phase-resolved data. The corresponding histogram of flux measurements was used to identify distributions of flux-states and the statistical significance of a lower-flux component was estimated with dedicated simulations of mock light curves. The energy spectra for different flux states were also reconstructed.ResultsWe confirm the presence of flaring-states which follow a log-normal flux distribution. Additionally, we discovered a low-flux state where the flux drops to as low as 18.4% of the intermediate-state average flux and remains there for several weeks. The transition time is observed to be as short as two days. The energy spectrum during the low-flux state resembles the extrapolation of the inverse-Compton spectrum measured at energies beyond several GeV energy, implying that the high-energy part of the synchrotron emission is dramatically depressed.ConclusionsThe low-flux state found here and the transition time of at most ten days indicate that the bulk (>75%) of the synchrotron emission above 108eV originates in a compact volume with apparent angular size ofθ≈ 0″.4tvar/(5 d). We tentatively infer that the so-called inner knot feature is the origin of the bulk of theγ-ray emission.
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螃蟹内结的特征：伽马射线耀斑的位置？
DOI：
10.1088/0004-637x/811/1/24
发表时间：
2015
期刊：
The Astrophysical Journal
影响因子：
--
作者：
A. Rudy;D. Horns;A. deLuca;J. Kolodziejczak;A. Tennant;Yajie Yuan;Rolf Buehler;Jonathon Arons;R. Blandford;P. Caraveo;E. Costa;S. Funk;E. Hays;A. Lobanov;C. Max;M. Mayer;R. Mignani;S. O’Dell;R. Romani;M. Tavani;M. Weisskopf
通讯作者：
M. Weisskopf
2013 年 3 月蟹状星云耀斑期间伽马射线通量的快速变化
DOI：
10.1088/2041-8205/775/2/l37
发表时间：
2013
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
M. Mayer;R. Buehler;E. Hays;C. C. Cheung;M. Dutka;J. Grove;M. Kerr;R. Ojha;R. Ojha
通讯作者：
R. Ojha
影响因子：
4.8
作者：
M. Lyutikov;S. Komissarov;O. Porth
通讯作者：
O. Porth
BATSE 观测到的蟹状星云发射的伽马射线光谱和变化
DOI：
10.1086/378700
发表时间：
2003
期刊：
The Astrophysical Journal
影响因子：
--
作者：
J. Ling;W. Wheaton
通讯作者：
W. Wheaton
影响因子：
6.5
作者：
Kuiper, L;Hermsen, W;McConnell, ML
通讯作者：
McConnell, ML