Heavy 'Seeds' and Mergers: The Recipe for Black Hole Growth express
The James Webb telescope discovered black holes — so named by John Wheeler, and Karl Schwarzschild described them as a light trap — which, just 500 million years after the Big Bang, already weighed more than a million Suns. It all began with heavy 'seeds' — future black holes with masses of tens of thousands of Suns, born in dense clumps of primordial gas within dark matter scaffolds. These embryos merged like voices in a choir, rapidly building up power. Later, gas absorption provided the main growth. Simulations showed that nearly half of the mass comes from mergers; otherwise, giants like the galaxy GN-z11 wouldn't have had time to grow.
Interestingly, the seeds probably collapsed directly from gas, skipping the star stage. Calculations promise up to four mergers per year for the LISA observatory — hundreds of times more than previous forecasts.
If space had sound, a black hole merger would sound like a low hum quickly soaring upward — a cosmic 'chirp'.