A jet of material is blasted out of the supermassive black hole at the heart of the galaxy M87.
Credit: NASA, STScI, Hubble
SYDNEY: Supermassive black holes are two or three times more massive than astronomers thought, according to a new supercomputer simulation that adds a missing ingredient: dark matter.
Astronomers have long known that dark matter makes up much of a galaxy's mass. But until now they haven't had the computing power to add dark matter into models that trace the orbits of stars within galaxies.
Now astronomers Karl Gebhardt, from University of Texas at Austin and Jens Thomas, of the Max Planck Institute for Extraterrestrial Physics in Munich, Germany, have added in this missing component to a simulation of the galaxy M87, a giant galaxy about 55 million light-years away.
No dark matter
Previous computer simulations had run models with stars, black holes and globular clusters. Gebhardt and Thomas added the gravitational effect of the halo of dark matter around the galaxy.
"In the past, we have always considered the dark halo to be significant, but we did not have the computing resources to explore it as well," said Gebhardt. He and Thomas used the Lonestar system supercomputer at the University of Texas at Austin's Texas Advanced Computing Centre to simulate conditions in M87.
To their surprise, they found that the mass of the central black hole was 6.4 billion times the Sun's mass, two to three times bigger than astronomers had previously estimated it to be. "We did not expect it at all," Gebhardt said.
They presented their result this week at a meeting of the American Astronomical Society in Pasadena, California. The research will also be published in the Astrophysical Journal later this year.
Quasar query
Gebhardt says he has since checked the result with both recent observations of the galaxy and new observations he made himself. The new observations were carried out using the Gemini North Telescope and the European Southern Observatory's Very Large Telescope and haven't yet been submitted for publication.
The researchers say the discovery may also solve a mystery concerning the huge mass of quasars.
Quasars are extremely bright, distant objects that are thought to represent black holes as you look deep into the past. Their brilliant light shines from material giving off radiation as it spirals under huger pressure into a hidden black hole.
I think what this article is
I think what this article is saying is that we have not changed our estimate for the total mass of M87, but rather we now think that a higher proportion of that mass is in the central black hole, so a lower proportion than we previously thought is in the galaxy's stars, gas and dust etc. Did I read that right? If so, I guess the dark matter problem still stands, because we're still looking for missing mass? Bit confused, so any explanations gratefully received!