High-energy cosmic rays are caused by black holes consuming stars.

ECONOMIST: Cosmic rays: They came from outer space | The

Interestingly, an April 18 paper in the journal Nature reported that upper limits for neutrinos measured from IceCube are low enough that gamma-ray bursts are unlikely to be the sole source of ultra-high energy cosmic rays.

CNN: Why gamma-ray burst shocked scientists

It has been detecting a rise in the number of high-energy particles, or cosmic rays, coming towards it from interstellar space, while at the same time recording a decline in the intensity of energetic particles coming from behind, from our Sun.

BBC: Voyager Solar System 'exit' debated

In 1966 Kenneth Greisen, Vadim Kuzmin and Georgiy Zatsepin showed that high-energy charged particles (cosmic rays are mostly atomic nuclei, and thus positively charged) should be slowed by collisions with the photons of the cosmic microwave background (radiation left over from the Big Bang that permeates all space).

ECONOMIST: Cosmic rays: They came from outer space | The

And when the solar wind is stronger, it is better at shielding the earth from high-energy charged particles from outer space known as cosmic rays.

ECONOMIST: Global warming: In flux | The