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arXiv 0810.1668astro-ph
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用费米LAT和H.E.S.S探测船帆座X PWN的无线电到X射线的联系

Probing the radio to X-ray connection of the Vela X PWN with Fermi LAT and H.E.S.S

O. C. de Jager, P. O. Slane, S. LaMassa

摘要:

从形态学上看,船帆座X PWN似乎由两个发射区域组成:而X射线(1 keV)和甚高能量(VHE)H.E.S.S.伽玛射线观测似乎定义了一个茧型形状的脉冲星南部,无线电观测揭示了一个大小为2度3度的扩展区域(包括茧区),也是船帆座脉冲星的南部。由于无线电和X射线之间的同步辐射没有宽视场(FoV)观测,我们不知道这两种成分的轻子(e+/-)光谱如何连接以及形态如何随能量变化。目前,我们发现,两个不同的轻子谱描述了各自的无线电和X射线/VHE伽马射线谱,与5 μ G的场强自洽地描述了多TeV域中的辐射谱断裂(或能量最大值),如H.E.S.S. (if解释为IC辐射),同时预测20 keV以上的总硬X射线通量(由宽FoV INTEGRAL仪器测量)在2倍内。如果同样的场强也代表了射电结构(包括灯丝),那么对应于最高射频的隐含IC分量应该揭示出一个相对明亮的高能伽马射线结构,费米LAT应该能够分辨它。然而,灯丝中更高的场强意味着船帆座X中的轻子更少,因此费米LAT信号更弱。

英文摘要:

Morphologically it appears as if the Vela X PWN consists of two emission regions: whereas X-ray (1 keV) and very high energy (VHE) H.E.S.S. gamma-ray observations appear to define a cocoon type shape south of the pulsar, radio observations reveal an extended area of size 2 deg by 3 deg (including the cocoon area), also south of the Vela pulsar. Since no wide field of view (FoV) observations of the synchrotron emission between radio and X-rays are available, we do not know how the lepton (e+/-) spectra of these two components connect and how the morphology changes with energy. Currently we find that two distinct lepton spectra describe the respective radio and X-ray/VHE gamma-ray spectra, with a field strength of 5 muG self-consistently describing a radiation spectral break (or energy maximum) in the multi-TeV domain as observed by H.E.S.S. (if interpreted as IC radiation), while predicting the total hard X-ray flux above 20 keV (measured by the wide FoV INTEGRAL instrument) within a factor of two. If this same field strength is also representative of the radio structure (including filaments), the implied IC component corresponding to the highest radio frequencies should reveal a relatively bright high energy gamma-ray structure and Fermi LAT should be able to resolve it. A higher field strength in the filaments would however imply fewer leptons in Vela X and hence a fainter Fermi LAT signal.

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