Gamma-ray observations of blazars and the intergalactic magnetic field spectrum
Gamma-ray observations of blazars and the intergalactic magnetic field spectrum
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耀变体的伽马射线观测和星系间磁场谱
DOI：
10.1103/physrevd.91.123514
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发表时间：
2015
影响因子：
5
通讯作者：
S. Gabici
中科院分区：
文献类型：
--
作者：
C. Caprini;S. Gabici
对blazar的超高能量观测可以用来限制星系间磁场的强度。通常作的一个简化假设是由随机取向的相同单元组成的恒定强度的磁场。在这篇文章中，我们论证了星系间磁场的结构确实需要更真实的描述。如果采用这样的描述，在短场关联长度的限制下，场强的观测界限将受到显著影响：尤其是，它们获得了对磁场功率谱的依赖。在星系际磁场是因果源产生的情况下，磁场大尺度谱指数为$n_B\geq_2$甚至偶数时，观测下界变得更受约3倍的限制。如果取而代之的是$-3<；n_B<；-2$，则观测下界明显松弛。这种具有非常红光谱的磁场原则上可以在膨胀过程中产生，但到目前为止仍是一种推测。
Very-high energy observations of blazars can be used to constrain the strength of the intergalactic magnetic field. A simplifying assumption which is often made is that of a magnetic field of constant strength composed by randomly oriented and identical cells. In this paper, we demonstrate that a more realistic description of the structure of the intergalactic magnetic field is indeed needed. If such a description is adopted, the observational bounds on the field strength are significantly affected in the limit of short field correlation lengths: in particular, they acquire a dependence on the magnetic field power spectrum. In the case of intergalactic magnetic fields which are generated causally, for which the magnetic field large scale spectral index is $n_B\geq 2$ and even, the observational lower bound becomes more constraining by about a factor 3. If instead $-3<n_B<-2$, the lower bound is significantly relaxed. Such magnetic fields with very red spectra can in principle be produced during inflation, but remain up to now speculative.