A pr 2 00 9 SEARCH FOR LORENTZ INVARIANCE VIOLATION EFFECTS WITH PKS 2155-304 FLARING PERIOD IN 2006 BY
A pr 2 00 9 SEARCH FOR LORENTZ INVARIANCE VIOLATION EFFECTS WITH PKS 2155-304 FLARING PERIOD IN 2006 BY
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A pr 2 00 9 搜索 2006 年 PKS 2155-304 燃烧期的洛伦兹不变性破坏效应
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通讯作者：
S. Wagner
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作者：
J. Bolmont;R. Bühler;A. Jacholkowska;S. Wagner
高能量，可变和遥远的来源，如活动星系核提供了一个很好的机会，以评估由于发射和传播的高能光子的影响。特别是，依赖于能量的时间滞后可能标志着洛伦兹对称性的破坏，正如一些量子引力模型所预测的那样。假设光速随E/EP线性变化，其中E是光子的能量，EP = 1.22 × 10 GeV是普朗克能量。飞行时间研究的目标是比较具有不同能量的光子的到达时间，假设它们同时发射。为此，通常使用两种遥远且可变的源：伽马射线暴（GRB）和活动星系核（AGN）。这张海报描述了对blazar PKS 2155-304的耀斑的分析，该耀斑是由H.E.S.S.探测到的。2006年7月，为了寻找依赖能源的时间滞后。耀斑期间的高通量（1.5小时内记录了10，000个光子）和高变异性（上升和下降时间为0.200秒）为寻找传播效应提供了一个很好的机会。两种方法被用来测量在不同的能量带的光子之间的时间滞后：互相关函数（CCF）和连续小波变换（CWT）。此外，还开发了玩具蒙特-卡罗模拟来校准误差和评估系统不确定度。量子引力能量标度的最终结果是CCF的EQG > 7.2 × 10 GeV，CWT的EQG> 5.2×10 GeV。这些结果之间的差异来自于CCF和CWT的能带选择不同的事实。这些结果比使用Mkn 421和Mkn 501进行的其他实验所获得的结果更具限制性，因为PKS 2155-304的距离几乎是其四倍，统计数据高出十倍。对大量活动星系核耀斑的进一步观测将是必要的，以便对可能的传播效应得出可靠的结论。目前和未来的实验，如CTA或AGIS，将大大提高我们在这一领域的能力。
Highly energetic, variable and distant sources such as Active Galactic Nuclei provide a good opportunity to evaluate effects due to the emission and the propagation of high energy photons. In particular, energy-dependant time-lags could sign a Lorentz Symmetry breaking as predicted in some Quantum Gravity models. It is assumed that the velocity of light could vary linearly with E/EP, where E is the energy of the photons and EP = 1.22 × 10 GeV is the Planck energy. The goal of time of flight studies is then to compare arrival times of photons with different energies, assuming they are emitted at the same time. For this, two kind of distant and variable sources are commonly used: Gamma-Ray Bursts (GRBs) and Active Galactic Nuclei (AGNs). This poster describes an analysis of a flare of the blazar PKS 2155-304 that was detected by H.E.S.S. in July 2006, in order to look for energy-dependant time-lags. The high flux (10 000 photons recorded in 1.5 hours) and the high variability (rise and fall times of ∼200 s) during the flare gave a good opportunity to search for propagation effects. Two methods were used to measure the time-lags between photons in different energy bands: a Cross-Correlation Function (CCF) and a Continuous Wavelet Transform (CWT). A toy Monte-Carlo simulation was developped in addition to calibrate the errors and evaluate systematic uncertainties. The final results on the quantum gravity energy scale were EQG > 7.2 × 10 GeV with the CCF and 5.2×10 GeV with the CWT. The difference between these results come from the fact that the energy bands were chosen differently for the CCF and the CWT. These results are more constraining than those obtained by other experiments with Mkn 421 and Mkn 501, due to the fact that PKS 2155-304 is almost four times more distant and the statistics are higher by a factor of ten. Further observations of a high number of AGN flares will be necessary to give robust conclusions on possible propagation effects. Present and future experiments such as CTA or AGIS will greatly improve our capabilities in this area.