Literature

Crucial features

The deflection of electron/positron pairs in the intergalactic magnetic field can lead to observable effects, including

  • a time dispersion
  • spectral signatures
  • as well as an apparent extension.

Important

What we observe is not nature in itself but nature exposed to our method of questioning.

Literature

1. Lower Limit on the Strength and Filling Factor of Extragalactic Magnetic Fields. arXiv:1009.1782

2. Time Delay of Cascade Radiation for TeV Blazers and the Measurement of the Intergalactic Magnetic Field. arXiv:1011.6660

../_images/basicprocess.png
\[c\Delta t = \lambda_{\gamma \gamma} + x - d\]

You can tell from law of sines that \(x = \frac{d\sin \theta_1}{\sin \theta_{dfl}}\) and \(\lambda_{\gamma \gamma} = \frac{d\sin \theta}{\sin \theta_{dfl}}\)

\[\begin{split}c\Delta t &= &\lambda_{\gamma \gamma} + \frac{d\sin (\theta_{dfl} -\theta)}{\sin \theta_{dfl}} -d\\ &= &\lambda_{\gamma \gamma}( 1 - \cos \theta_{dfl}) + d(\cos \theta - 1)\end{split}\]

3. Gamma rays as probes of the Universe. arXiv:1602.06825

Why do we study VHE gamma ray? - Lorentz invariant violation predicted by theory beyound standard modle.

  • Very high energy photons travel a very very long distance provide a window to infer the properties of intergalactic medium.

    It can be understand intuitively. Since the existence of intergalactic medium affects the track VHE photons. In what kind of way did it affects is still a question to me.

How much have we achieved?

4. Measuring the correlation length of intergalactic magnetic fields from observations of gamma-ray induced cascades. arXiv:13072753