The most massive black hole yet weighed lurks at the heart of the relatively nearby giant galaxy M87.
The supermassive black hole is two to three times heftier than previously thought, a new model showed, weighing in at a whopping 6.4 billion times the mass of the sun. The new measure suggests that other black holes in nearby large galaxies could also be much heftier than current measurements suggest, and it could help astronomers solve a longstanding puzzle about galaxy development.
"We did not expect it at all," said team member Karl Gebhardt of the University of Texas at Austin.
The discovery was announced Monday at the 214th meeting of the American Astronomical Society.
The finding "is important for how black holes relate to galaxies," said team member Jens Thomas of the Max Planck Institute for Extraterrestrial Physics in Germany. "If you change the mass of the black hole, you change how the black hole relates to the galaxy."
Because of this relationship, the revised mass could impact astronomers' theories of how galaxies grow and form.
Higher black hole masses could also solve a paradox of the masses of faraway, developing galaxies called quasars. These mysterious denizens of the early universe are very bright, developing galaxies with black holes surrounded by gas and dust, all rife with star formation. Quasars are colossal, around 10 billion solar masses, "but in local galaxies, we never saw black holes that massive, not nearly," Gebhardt said.
"The suspicion was before that the quasar masses were wrong," he said. But "if we increase the mass of M87 two or three times, the problem almost goes away."
Why M87 matters
M87 is 50 million light-years away. Nearly three decades ago, it was one of the first galaxies suggested to harbor a central black hole. Now astronomers think that most large galaxies, including our own Milky Way, have supermassive black holes at their centers.
M87 also has an active jet shooting light out of the galaxy's core, created where matter swirls closer to the black hole and approaches the speed of light, then combines with tremendous magnetic fields. The spat-out material helps astronomers understand how black holes attract and gobble up matter, a sloppy process in which all is not consumed.
These factors make M87 "the anchor for supermassive black hole studies," Gebhardt said.
While the new mass of M87 is based on a model, recent observations from the Gemini North Telescope in Hawaii and the European Southern Observatory's Very Large Telescope in Chile support the model findings.
The study of M87's mass will also be detailed later this summer in the journal Astrophysical Journal.
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