`No link between dark matter, black holes’

A new study has found that there is no direct connection between black holes and dark matter.

London: A new study has found that there is no direct connection between black holes and dark matter.

The theory first took root when massive black holes were found at the centres of almost all galaxies, where the largest galaxies - which are also the ones embedded in the largest halos of dark matter - harbour the most massive black holes.

Scientists at the Max Planck Institute of Extraterrestrial Physics, the University Observatory Munich, and the University of Texas in Austin, have found otherwise.

All galaxies are embedded in halos of so-called dark matter, which cannot be observed directly, but can be measured through its effect on the motion of stars, gas, and dust.

Scientists don’t know what this dark matter really is. The other invisible component in a galaxy is the supermassive black hole at its center, which also cannot be observed directly. The mass of the black hole can only be inferred from the motion of stars around it.

In 2002, it was speculated that the unknown physics of exotic dark matter somehow controls the growth of black holes.

To test this idea, the astronomers John Kormendy from the University of Texas and Ralf Bender from the Max Planck Institute for Extraterrestrial Physics and the University Observatory Munich carried out high-quality spectral observations of many disk, bulge, and pseudobulge galaxies.

Results showed increased accuracy of the resulting galaxy dynamics parameters, which led them to the conclusion that there is almost no correlation between dark matter and black holes.

Kormendy and Bender found that galaxies without a bulge - even if they are embedded in massive dark matter halos - can at best contain very low mass black holes.

“It is hard to conceive how the low-density, widely distributed non-baryonic dark matter could influence the growth of a black hole in a very tiny volume deep inside a galaxy,” said Bender.

“It seems much more plausible that black holes grow from the gas in their vicinity, primarily when the galaxies were forming.”

Their findings are published in a Letter to the journal Nature on 20th January.


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