[RadioAstronomer]

It seems to me that if some process occurs once every 10 million years, then a byproduct travelling at the speed of light will be 10 million light years away at the next occurence.

Indeed if the sound waves were traveling at c, they would be. The waves heat up the gas, which then emit X-rays.

[KayEyeDoubleDee]

Indeed if the sound waves were traveling at c, they would be. The waves heat up the gas, which then emit X-rays.

But it is the concentric rings of X-rays which is actually observed, right? Wouldn't these rings grow to be 10 million light years in diameter between cycles?

[KayEyeDoubleDee]

I think I get it. The sound waves are producing an "image", which is seen via the Xray emissions.