Relevance of axion-like particles for very-high-energy astrophysics
Relevance of axion-like particles for very-high-energy astrophysics
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DOI：
10.1103/physrevd.84.105030
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
A. Angelis;G. Galanti;M. Roncadelli
中科院分区：
文献类型：
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作者：
A. Angelis;G. Galanti;M. Roncadelli
标准模型的许多扩展预言了ALP的存在，这是一种具有双光子耦合的非常轻的自旋零玻色子。光子ALP振荡发生在存在外部磁场的情况下，并且ALP可以导致对天体物理源的测量光子谱的可观察影响。当用切伦科夫望远镜H.E.S.S.观测耀变体时，MAGIC、CANGAROO III和VERITAS。星系在宇宙演化过程中产生的河外背景光（EBL）引起了VHE波段的光源变暗。大尺度磁场中的光子ALP振荡可以大大减少这种调光，并且由此产生的耀变体光谱变得比预期的更难。我们发现，对于轻于5 x 10 ^{-10} eV的ALP，光子的存活概率大于传统物理学在几百GeV以上预测的。这是一个明确的预测，可以用计划中的切伦科夫望远镜阵列和HAWC进行测试。此外，我们提供了一个新的解释的VHE耀变体检测到目前为止，根据该观测光谱指数的值的大的传播主要是由于在源距离的广泛传播，而不是其内部的物理性质的大的变化。
Many extensions of the Standard Model predict the existence of ALPs, which are very light spin-zero bosons with a two-photon coupling. Photon-ALP oscillations occur in the presence of an external magnetic field, and ALPs can lead to observable effects on the measured photon spectrum of astrophysical sources. An intriguing situation arises when blazars are observed with the Cherenkov Telescopes H.E.S.S., MAGIC, CANGAROO III and VERITAS. The extragalactic background light (EBL) produced by galaxies during cosmic evolution gives rise to a source dimming which becomes important in the VHE band. This dimming can be considerably reduced by photon-ALP oscillations in the large-scale magnetic fields, and the resulting blazar spectra become harder than expected. We find that for ALPs lighter than 5 x 10^{-10} eV the photon survival probability is larger than predicted by conventional physics above a few hundred GeV. This is a clear-cut prediction which can be tested with the planned Cherenkov Telescope Array and HAWC. Moreover, we offer a new interpretation of the VHE blazars detected so far, according to which the large spread in the values of the observed spectral index is mainly due to the wide spread in the source distances rather than to large variations of their internal physical properties.