They cannot. In fact, X-rays are EM just at a higher frequency than visible EM (light).
So why are they waiting for a light show to start (if it does). I was going to ask the same question. If X and Gamma rays have already hit the instruments, wouldn't the explosion already be showing in the visible wavelengths?
Is this possibly one of those sterilizing explosions that wipe out life throughout the galaxy ?
I don't see how X-rays could propagate faster than visible light.
They cannot. In fact, X-rays are EM just at a higher frequency than visible EM (light).
Right, starting about 10 nm wavelength and getting shorter. So whatever produced them isn't also producing visible light.