It would have that effect if the energy was in the form of photons, but it is gravity waves.
If you release 5 solar masses of energy in one second, electromagnetically and with the same spectrum as the sun, half way between the Milky Way and Andromeda, every star in both galaxies would see it only a little dimmer as Sol appears on Mars.
What determines whether the merger is non-radiative in the EM? Why was the collision of two neutron stars radiative?
It seems like the universe would be immeasurably more dangerous than it already is, if all of these events were primarily EM radiative in nature.
As a non-physicist, I'm also curious how gravity is simultaneously so much weaker than the other forces, but yet spacetime seems to be able to stably survive these immense releases of energy.
If you release 5 solar masses of energy in one second, electromagnetically and with the same spectrum as the sun, half way between the Milky Way and Andromeda, every star in both galaxies would see it only a little dimmer as Sol appears on Mars.
https://www.wolframalpha.com/input/?i=%28%28%285+solar+mass%...