The mass of black holes increases

The black hole in the heart of the giant galaxy M87 is two to three times more massive than previously thought - the same could also apply to other galaxies

The galaxy M87

Austin (USA) / Garching - Almost every galaxy contains a supermassive black hole in its center with a mass million or even billion times the mass of our sun. But the astronomers may have significantly underestimated the masses of these gravity monsters so far. This is the conclusion drawn by an American-German research duo from the best modeling of the star movements to date in the nearby giant galaxy M87. The calculations of the two scientists provide a mass of 6.4 billion solar masses for the black hole in M87 - two to three times as much as previous estimates. This could also explain the riddle of the high quasar masses, according to the astronomers in their report, which will soon be published in the "Astrophysical Journal".

"The black holes in quasars are very large - around ten billion solar masses," explains Karl Gebhardt from the University of Texas at Austin. Quasars are brightly radiating nuclei from distant galaxies in the early universe. "But we have never found such massive black holes in galaxies in our local area. We therefore thought the quasar masses might be wrong. But if we increase the mass of the black hole of M87 by two to three times, it disappears Discrepancy almost. "

In order to determine the masses of galaxies and their black holes, astronomers have to measure the movement of stars in these systems and compare them with model calculations. Gebhardt and his colleague Jens Thomas from the Max Planck Institute for Extraterrestrial Physics in Garching have now for the first time also included the halo made of dark matter that surrounds the galaxy in these model calculations. "In the past we lacked the computing power to take the dark halo into account," says Gebhardt. The two researchers were now able to fall back on a supercomputer from the University of Texas, which can perform 62 trillion floating point operations per second.

The researchers unexpectedly found that taking dark matter into account requires significantly larger masses for the central black hole in M87 in order to explain the star movements measured. Gebhardt and Thomas assume that this also applies to the determination of the mass of black holes in other galaxies. Since the supermassive black holes also influence the evolution of galaxies, the researchers believe that this may also mean that the theory of the cosmic evolution of galaxies must be revised.