How colossal can black holes get? – Stupendously large

Astrophysicists are spotting an entirely new class of giant black holes that dwarf even the supermassive ones located at the centre of galaxies. Could there be some even more gargantuan lurking out there in the darkness of space?

At the centre of our galaxy Milky Way lives a gigantic black hole. Though it is just as wide as our Sun, it is millions of times heavier than sun. Its extreme gravitational pull churns the interstellar dust and gas around it. This SMBH (supermassive black hole) is the beating heart of the Milky Way, driving the creation and evolution of our galaxy for its full 13 billion-year-history, helping to give rise to planetary systems like our own. Sporadically, a star wanders too close and is ripped apart, blinking out without a trace of past existence. It is a frightening beast, with the power to create and destroy on an epic scale.

Nearly every large galaxy has a SMBH at its centre, but in the grand scheme of the Cosmos, ours – called Sagittarius A* – is an absolute featherweight. Over the past decade, astrophysicists have discovered black holes much, much grander, known as ultramassive black holes. Some are 1,000 times more colossal than Sagittarius A* and large enough to span the entire width of our planetary system (solar system).

The incomparable view offered by JWST (the James Webb Space Telescope) is also giving us a new insight into how these colossuses grew at the dawn of time. But there are just as many question marks – where did they come from basically, and how big can they actually get? Measuring the size of such massive and faraway objects (which by their very definition cannot be directly observed) is complicated, but we are aware some of the largest are astoundingly big. One of the imposing candidates to be discovered to date, known as Ton 618, is found lurking at the middle of a quasar roughly 18 billion light years from Earth. It is estimated to be whopping 66 billion times the mass of our Sun and is up to mind-boggling 40 times wider than the distance between Neptune and our Sun. The black hole at the centre of a cluster galaxy termed Holm 15A was also recently estimated to be about 44 billion times heavier than the Sun, 30 time the Sun-Neptune distance. These are irrefutably huge. But some researchers think there could be even larger monsters skulking out there.