logo

Massive neutrinos solve a cosmological conundrum

   
   
Galaxy2
10 Feb 2014 09:01:00.000

Scientists have solved a major problem with the current standard model of cosmology by combining results from the Planck spacecraft and measurements of gravitational lensing to deduce the mass of ghostly sub-atomic particles called neutrinos.

The team, from the universities of Nottingham and Manchester, used observations of the Big Bang and the curvature of space-time to accurately measure the mass of these elementary particles for the first time.

The recent Planck spacecraft observations of the Cosmic Microwave Background (CMB) – the fading glow of the Big Bang – highlighted a discrepancy between these cosmological results and the predictions from other types of observations.

Click here for full story

Massive or massless?

The CMB is the oldest light in the Universe, and its study has allowed scientists to accurately measure cosmological parameters, such as the amount of matter in the Universe and its age. But an inconsistency arises when large-scale structures of the Universe, such as the distribution of galaxies, are observed.

Dr Adam Moss, from The University of Nottingham’s School of Physics and Astronomy said: “We observe fewer galaxy clusters than we would expect from the Planck results and there is a weaker signal from gravitational lensing of galaxies than the CMB would suggest.

“A possible way of resolving this discrepancy is for neutrinos to have mass. The effect of these massive neutrinos would be to suppress the growth of dense structures that lead to the formation of clusters of galaxies.”

Neutrinos interact very weakly with matter and so are extremely hard to study. They were originally thought to be massless but particle physics experiments have shown that neutrinos do indeed have mass and that there are several types, known as flavours by particle physicists. The sum of the masses of these different types has previously been suggested to lie above 0.06 eV (much less than a billionth of the mass of a proton).

'Flavours' of neutrinos

Dr Moss and Professor Richard Battye from The University of Manchester have combined the data from Planck with gravitational lensing observations in which images of galaxies are warped by the curvature of space-time. They conclude that the current discrepancies can be resolved if massive neutrinos are included in the standard cosmological model. They estimate that the sum of masses of neutrinos is 0.320 +/- 0.081 eV (assuming active neutrinos with three flavours).

Professor Battye added: “If this result is borne out by further analysis, it not only adds significantly to our understanding of the sub-atomic world studied by particle physicists, but it would also be an important extension to the standard model of cosmology which has been developed over the last decade.”

The paper is published in Physical Review Letters and has been selected as an Editor’s choice. 

A copy of the paper is available from http://arxiv.org/abs/1308.5870or http://prl.aps.org/abstract/PRL/v112/i5/e051303

— Ends —

Our academics can now be interviewed for broadcast via our new Globelynx fixed camera facility at the University. For further information please contact a member of the Communications team on +44 (0)115 951 5798, email mediahub@nottingham.ac.uk or see the Globelynx website for how to register for this service.

For up to the minute media alerts follow us on Twitter

Notes to editors: The University of Nottinghamhas 43,000 students and is ‘the nearest Britain has to a truly global university, with campuses in China and Malaysia modelled on a headquarters that is among the most attractive in Britain’ (Times Good University Guide 2014). It is also the most popular university among graduate employers, the world’s greenest university, and winner of the Times Higher Education Award for ‘Outstanding Contribution to Sustainable Development’. It is ranked in the World's Top 75 universities by the QS World University Rankings.

Impact: The Nottingham Campaign, its biggest-ever fundraising campaign, is delivering the University’s vision to change lives, tackle global issues and shape the future. More news…

Story credits

More information from Dr Adam Moss, School of Physics & Astronomy, The University of Nottingham adam.moss@nottingham.ac.uk 

Emma Rayner

Emma Rayner - Media Relations Manager

Email: emma.rayner@nottingham.ac.uk Phone: +44 (0)115 951 5793 Location: University Park
 

Additional resources

No additional resources for this article

Related articles

Nottingham physicists are winning the fight for equality

Published Date
Wednesday 22nd January 2014

Powerful supercomputer to offer a glimpse of the early universe

Published Date
Wednesday 19th February 2014

Major European grant for exploration of quantum matter

Published Date
Monday 1st July 2013

Navigating our way through solar threats

Published Date
Tuesday 23rd July 2013

Top physics medals for University scientists

Published Date
Monday 1st July 2013

News and Media - Marketing, Communications and Recruitment

The University of Nottingham
C Floor, Pope Building (Room C4)
University Park
Nottingham, NG7 2RD

telephone: +44 (0) 115 951 5765
email: communications@nottingham.ac.uk