Three monster black holes have turned up in Earth's cosmic neighborhood, astronomers reported Thursday, prompting questions about whether black holes are born before the galaxies that contain them.
The new trio of so-called supermassive black holes are in the constellations Virgo and Aries, between 50 million and 100 million light years from Earth. Even though a light year -- the distance light travels in a year -- is about six trillion miles, these distances are just around the corner by celestial standards.
Their proximity is not unusual, but their mass is: Each weighs between 50 million and 100 million times the mass of our sun. That puts them in a comparatively small club of giant black holes. Only 20 are known to exist; most black holes weigh just a few times the sun's mass.
Less than a decade ago, even the notion of black holes was a matter for debate. Now most astronomers accept their existence but question their role in the universe, especially when it comes to the formation of galaxies.
The massive black holes are relics of quasars, Douglas Richstone of the University of Michigan said at a briefing at a meeting of the American Astronomical Society in Atlanta. Quasars are immensely powerful bright objects that shine as bright as a trillion suns within an area the size of Mars.
Quasars developed long before most stars formed in galaxies, Richstone said. If these big black holes developed from quasars, as Richstone and his colleagues believe, they must have been present at the height of the quasar era -- when the universe was about a billion years old.
This raises the question, Richstone said, of "Which comes first, the massive black hole or the galaxy that is its host?"
These astronomers believe that galaxies form and evolve in close relation to the massive black holes at their centers, and the mass of black holes is related to the mass of the central part of the galaxy.
"Radiation and high-energy particles released by the formation and growth of black holes are the dominant sources of heat and kinetic energy for star-forming" in embryonic galaxies, Richstone said.
Black holes are mysterious matter-sucking drains in space, taking in everything that comes within their gravitational pull, not letting even light escape.
But while black holes themselves cannot be seen, they can often be identified by the heat generated by matter as it swirls into them.
Stars speed up as they come relatively close to black holes, and their mass can be estimated by clocking the pattern of the stars' velocity as they go by.
