The youngest epoch of the universe we can observe so far is the CMB. It is theorized that systematic and accurate measurement of gravitational waves could allow us to "see" events from even earlier cosmic epochs. If we go to even earlier cosmic epochs we have what must have been a very singular cosmic event, the huge annihilation of matter and antimatter which happened after the end of Inflation and which presumably left over a "small" excess of matter which went on to form our familiar matter universe. My question is, such a cosmic scale matter-antimatter annihilation must have had produced a truly immense amount of energy. I don't really know which kind of energy and which properties, I assume it must have been electromagnetic radiation of huge intensity. Is it conceivable that we will ever be able to detect any remnants of that immense energy burst in the very early universe, and if so which form would it have, gravitational waves or any other form? Would that immensely energetic event have left any observable clues in our currently observable universe? Thanks!