Usually they reach us as photons with energy above 100 keV. In the electromagnetic spectrum, they are located in the high frequencies region and therefore have a small wavelength. Radioactive materials can emit gamma rays. They penetrate deep into living tissues and can cause cancer. Similar to light, gamma rays are composed of photons, but in gamma rays, these photons have extremely high energy.
Imagine that you can get the energy from every star in a radius of 100 million light-years. Of thousands of galaxies, each of which has billions of stars. Try to imagine that you are capable of taking this kind of energy and using it in the greatest super weapon in the universe. The ruin you will cause is unimaginable.
In fact, you do not have to imagine it, because all of this already exists in the form of gamma rays. What are these “space snipers” that shoot the Universe at random intervals. What happens if they hit us?
Another interesting video on the popular YouTube channel Kurzgesagt – In a Nutshell will try to answer this question.