Feeds

Black holes bigger than first thought

Boffins ready to ditch linear galaxy size = black hole size assumption

The smart choice: opportunity from uncertainty

A bit of “astronomical shorthand” applied to make galactic mathematics easier to deal with might have to be abandoned, according to researchers from Swinburne University.

According to Professor Alister Graham from Swinburne’s Centre for Astrophysics and Supercomputing, the decade-old assumption that black holes account for a fixed fraction of galactic mass is incorrect.

The usual assumption was that black holes grew bigger in step with the growth of the galaxy. Instead, the Swinburne research suggests that the assumed linear relationship between galaxy size and black hole size is much more complex.

“We now know that each ten-fold increase of a galaxy's stellar mass is associated with a much larger 100-fold increase in its black hole mass,” Professor Graham states in this university announcement. “This has widespread implications for our understanding of galaxy and black hole coevolution.”

The bigger the black hole, the hungrier. Image: Gabriel Perez Diaz

In smaller galaxies, he notes, “the star clusters, which can contain up to millions of stars, really dominate over the black holes.”

The analysis also suggests that there should be a large number of intermediate-mass black holes out there, waiting to be discovered. With a mass between that of a single star and a million stars, intermediate black holes have been hard to find.

Professor Graham says they may lie within galaxies already known to harbor one black hole, and should be detectable by the new generation of extremely large telescopes.

His group combined observations from Hubble, Europe’s Very Large Telescope in Chile, and the Keck Telescope in Hawaii. They analysed 77 galaxies and their central black holes, calculating the mass of the black hole based on the orbital speed of nearby stars. ®

The Power of One Infographic

More from The Register

next story
World Solar Challenge contender claims new speed record
One charge sees Sunswift travel 500kms at over 100 km/h
SMELL YOU LATER, LOSERS – Dumbo tells rats, dogs... humans
Junk in the trunk? That's what people have
The Sun took a day off last week and made NO sunspots
Someone needs to get that lazy star cooking again before things get cold around here
Boffins discuss AI space program at hush-hush IARPA confab
IBM, MIT, plenty of others invited to fill Uncle Sam's spy toolchest, but where's Google?
Beancounters tell NASA it's too poor to fly planned mega-rocket
Space Launch System would need another $400m and a lot of time
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
prev story

Whitepapers

Top three mobile application threats
Prevent sensitive data leakage over insecure channels or stolen mobile devices.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Build a business case: developing custom apps
Learn how to maximize the value of custom applications by accelerating and simplifying their development.