Feeds

Missing matter found by squinting through gravitational lens

Fancy new particles not needed as Planck team weighs galaxies anew

Build a business case: developing custom apps

Some of the universe's “missing matter” might have been found in an unexpected place: exactly where it ought to be, sitting in galaxies.

The missing matter question arose when the ESA's Planck mission team published this paper on Arxiv, in which they pointed out an apparent discrepancy between the “wrinkles” in the cosmic background radiation, and the amount of matter that seemed to exist in galactic clusters.

Planck's result is based on a phenomenon dubbed the Sunyaev–Zel’dovich effect: the microwave-wavelength photons of the cosmic background radiation are given extra energy by collisions with the hot gases of galactic clusters. Measurement of the difference between “unboosted” and “boosted” photons should predict the mass of the clusters.

The problem was that Planck's Sunyaev–Zel’dovich predictions suggested that about 40 per cent of the mass in the clusters was missing.

That kind of a mismatch was always going to send astrophysicists on a mission to work out an explanation, and according to Nature, proposed explanations went so far as to include suggestions of new and previously-unimagined types of neutrino that are heavier than the ones we know about.

Two new studies, Nature reports, suggest that the discrepancy isn't because there's missing mass: rather, the new analyses suggest that the “missing matter” results can be explained by the phenomenon of gravitational lensing.

Gravitational lensing, discussed by early 20th-century physicists including Einstein, is a phenomenon in which the huge gravitation of objects like galactic clusters will bend light passing by them.

The amount of lensing provides a way to estimate galactic mass, and that's what the new studies focus on. Only one of the studies, from the Weighing the Giants (WtG) project, has been published – here – and its authors say that with a robust calibration of “weak lensing”, the discrepancies in the Planck estimates can be resolved.

The WtG project sampled 22 of the galactic clusters also measured by Planck, and comes up with a mass estimate that's 43 per cent higher than the mass predicted by Planck's use of the Sunyaev–Zel’dovich effect.

“Adopting the WtG weak-lensing-based mass calibration would substantially reduce the tension found between the Planck cluster count cosmology results and those from CMB temperature anisotropies,” the group writes.

As Nature notes, the study of galactic mass is one of the more difficult challenges in cosmology, with lots of uncertainty. The Planck group is now conducting its own re-analysis with a more finely tuned mass calibration, which should be released later this year. ®

Securing Web Applications Made Simple and Scalable

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?
Bad back? Show some spine and stop popping paracetamol
Study finds common pain-killer doesn't reduce pain or shorten recovery
BEST BATTERY EVER: All lithium, all the time, plus a dash of carbon nano-stuff
We have found the Holy Grail (of batteries) - boffins
Forty-five years ago: FOOTPRINTS FOUND ON MOON
NASA won't be back any time soon, sadly
Jurassic squawk: Dinos were Earth's early FEATHERED friends
Boffins research: Ancient dinos may all have had 'potential' fluff
MARS NEEDS OCEANS to support life - and so do exoplanets
Just being in the Goldilocks zone doesn't mean there'll be anyone to eat the porridge
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.
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.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.