Electromagnetism in astrophysics What is the most important electromagnetic phenomena involved in astrophysics?, I am working in a presentation of magnetars, pulsars and magnetic field of planets and I would like to know if there are more interesting phenomena that I should mention, I trying to find about electromagnetism in black holes but I only found about the no hair theorem and papers that do not say anything in concrete terms
 A: Probably the most direct example is synchrotron radiation. This is the case in which an electron is accelerating by moving in along a curved path (e.g., a helix). As it is accelerated, it emits photons in the radio spectrum:
 
(source)
Another big one would be bremsstrahlung in which an electron moving along a path is decelerated near the presence of a heavy nucleus. The emitted photon is typically in the X-ray regime.

(source)
A: 90% of Astrophysics is to do with electromagnetic phenomena. Bar neutrinos or directly grabbing stuff in our own solar system, there's not much else you can do but observe the electromagnetic radiation coming from out there.
Your question is therefore massively broad. But here are some examples you could research.
Rayleigh scattering observed in the atmospheres of exoplanets.
http://arxiv.org/abs/1006.3525
Thomson scattering observed from coronal mass ejections around the Sun.
http://solarphysics.livingreviews.org/Articles/lrsp-2012-3/articlesu6.html
Synchrotron radiation from active galactic nuclei.
http://asd.gsfc.nasa.gov/Volker.Beckmann/school/download/Longair_Radiation2.pdf
Thermal bremsstrahlung radiation generated in the hot gas that pervades the space in a cluster of galaxies.
http://ned.ipac.caltech.edu/level5/March02/Sarazin/Sarazin5_1_3.html
Faraday rotation to estimate magnetic field strengths.
http://en.wikipedia.org/wiki/Faraday_effect
Using polarimetry to investigate unified models for AGN.
http://www.physics.purdue.edu/~mlister/articles/antonucci1993_ann_rev.pdf
Relativistic beaming and apparent superluminal motion.
http://jila.colorado.edu/~ajsh/insidebh/4dperspective.html
