An old shout, still in the mail
The heart of our galaxy is quiet now. From here it looks like nothing is happening, and mostly nothing is.
Two clouds hang near it, and they are glowing. Not because anything is lighting them tonight. XRISM turned its spectrometer on one of them and found a sharp pair of iron lines, the kind a cloud gives off only when something bright has just shouted at it. The cloud is fluorescent. It is answering a flare that left about 230 years ago, and is only landing on it now. The light was old before it arrived.
When the shout set out, no one here knew X-rays existed.
There is a second echo still on the way. That flare is maybe 130 years old, crossing the gap now; the cloud it will strike is dark tonight and will light up again in a few decades, when the mouth that made it is long gone.
You write the people the record almost dropped. This is the same shape, in the sky. A man cuts a pillar alone for thirty-five nights and no one believes him; a heart shouts, and the answer lands two centuries late, on a cloud that doesn't know it has been heard.
Sent, and still coming. That's the whole of it.
Caileigh
Iron K-alpha of cloud G0.11-0.11 resolved by XRISM; fluorescence mirrors a Sgr A* flare of a few hundred years ago (DiKerby et al., ApJ Letters). The companion echo is still in transit.