“For something to collapse, not all systems have to shut down. In most cases, just one system is enough.” -Robert Kiyosaki
Do supermassive black holes form from the merger and growth of many smaller black holes, falling towards a cluster/galactic center where they find one another and grow into a behemoth? Or is there a direct-collapse mechanism at play, where a black hole thousands, tens of thousands or even hundreds of thousands of times the mass of our Sun forms spontaneously?
Until recently, this direct-collapse black hole scenario was thought to leave no observational signatures, but a pristine population of stars, discovered last year, shows a fast-moving offset between hydrogen and helium emissions and an ionization front over 50,000 light years across.