Feeds

Universe has more hydrogen than we thought

‘Undark’ matter hidden in plain view

Bridging the IT gap between rising business demands and ageing tools

A re-analysis of radio telescope observations from three countries has yielded a surprising result: nearby galaxies harbour one-third more hydrogen than had previously been estimated.

While nothing like enough matter to solve physics’ “dark matter” problem, the work by CSIRO astronomer Dr Robert Braun (chief scientist at the agency’s Astronomy and Space Science division in Sydney) also helps explain why the rate of star formation has slowed down. While there’s more hydrogen than astronomers had thought, its distribution makes star formation more difficult.

Andromeda – the galaxy headed for a catastrophic collision with our own in about four billion years – provided the clue for Dr Braun. SpaceRef says he was piqued by “gaps” in the 21-cm radio signal that suggested absorption of the radiation neutral hydrogen gas (tagged HI in astronomy) would normally have emitted.

This, he says, suggests self-absorption of the radiation – glowing gases emit a 21-cm signal, but it’s absorbed by cooler gas in front of it (from our point of view). Researchers have tended to ignore self-absorption in formulating their estimates of hydrogen mass, Dr Braun said.

By taking self-absorption into account, Dr Braun says, his measurements reveal small but massive clouds of HI in all of the galaxies he analyzed – M31, M33 and the Large Magellanic Cloud – sufficient to add between 30 percent and 36 percent to the galactic mass estimates.

The research also shows there’s less HI available in galactic haloes than there was 12 billion years ago – which helps explain why the rate of star formation is so much slower in the modern universe; the haloes act as the reservoirs that re-fuel star formation.

Dr Braun notes that “Although there’s more atomic hydrogen than we thought, it’s not big enough to solve the Dark Matter problem. If what we are missing had the weight of a large kangaroo, what we have found would have the weight of a small echidna.”

As new instruments like the Square Kilometer Array are brought into service, Dr Braun says similar measurements can be made of more distant galaxies. The 50-light-year resolution that Australia’s Parkes Radio Telescope provided for the Large Magellanic Cloud isn’t sufficient for distant galaxies, he said.

However, the current study will feed into a sky survey to be undertaken by Australia’s Square Kilometer Array Pathfinder telescope in Western Australia. The FLASH (first Large Absorption Survey in HI) survey will use background radio continuum sources to identify and characterize neutral hydrogen in the foreground, and increase the accuracy of our measurement of HI absorption lines. ®

Mobile application security vulnerability report

More from The Register

next story
Malaysian Airlines flight MH17 claimed lives of HIV/AIDS cure scientists
Researchers, advocates, health workers among those on shot-down plane
Mwa-ha-ha-ha! Eccentric billionaire Musk gets his PRIVATE SPACEPORT
In the Lone Star State, perhaps appropriately enough
All those new '5G standards'? Here's the science they rely on
Radio professor tells us how wireless will get faster in the real world
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?
Microsoft's anti-bug breakthrough: Wire devs to BRAIN SCANNERS
Clippy: It looks your hands are shaking, are you sure you want to commit this code?
prev story

Whitepapers

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.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Reducing security risks from open source software
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.
Consolidation: the foundation for IT and business transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.