Discovery of biggest black holes ever may shed light on galaxy formation
Astronomers have discovered evidence for the most massive black holes yet identified, an observation that could help write the history of galaxy formation and evolution over the universe’s 13.7 billion-year history.
Black holes are objects whose gravity is so strong even light can’t escape. Individual stars can collapse into black holes at the end of their lives. And supermassive descendent black holes lurk in the centers of most galaxies.
Each of these newly discovered black holes sits at the center of a galaxy. Each tips the scales at about 10 billion times the sun’s mass, roughly 3 billion solar masses more than the previous record-holder.
One supermassive black hole lurks within a giant elliptical galaxy tagged as NGC 3842, located 320 million light-years from Earth in a cluster of galaxies in the constellation Leo. The other calls NGC 4889 home - another giant elliptical galaxy, 336 million light-years away in a cluster of galaxies in the constellation Coma Berenices.
The Milky Way hosts a much smaller version of these monsters. It tips the scales at roughly 4 million solar masses. If placed at the center of the solar system, its event horizon - the point of no return for matter falling into it - would reach the orbit of Mercury. The event horizons for these new-found behemoths would occupy a patch of space stretching five times father than Pluto’s orbit, with their gravity influencing objects some 4,000 light-years away.
Where the Milky Way’s supermassive black hole would fit inside the orbit of Mercury, each of these newly detected behemoths encompasses a patch of space five times larger than the orbit of Pluto, their gravity influencing objects up to another 4,000 light-years beyond.
“Black holes play some sort of role in shaping how their galaxies turn out,” says Nicholas McConnell, a student en route to a PhD at the University of California at Berkeley and the lead author of the formal paper reporting the results in the Dec. 8 issue of the journal Nature. But that role remains murky.