̽��ֱ�� of Cambridge - George Efstathiou

Cambridge scientists receive Royal Society awards

Anonymous — Mon, 20 Jul 2015 13:44:01 +0000

̽��ֱ��Royal Society, the UK’s independent academy for science, has announced the recipients of its 2015 Awards, Medals and Prize Lectures. ̽��ֱ��scientists receive the awards in recognition of their achievements in a wide variety of fields of research. ̽��ֱ��recipients from the ̽��ֱ�� of Cambridge are:

Professor George Efstathiou FRS (Institute of Astronomy) receives the Hughes Medal for many outstanding contributions to our understanding of the early Universe, in particular his pioneering computer simulations, observations of galaxy clustering and studies of the fluctuations in the cosmic microwave background.

Professor Benjamin Simons (Wellcome Trust/Cancer Research UK Gurdon Institute, Cavendish Laboratory) receives the Gabor Medal for his work analysing stem cell lineages in development, tissue homeostasis and cancer, revolutionising our understanding of stem cell behaviour in vivo.

Professor Russell Cowburn FRS (Department of Physics) receives the Clifford Paterson Medal and Lecture for his remarkable academic, technical and commercial achievements in nano-magnetics.

Dr Madan Babu Mohan (MRC Laboratory of Molecular Biology) receives the Francis Crick Medal and Lecture for his major and widespread contributions to computational biology.

View the full list of recipients.

Four Cambridge scientists have been recognised by the Royal Society for their achievements in research.

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Planck reveals first stars were born late

sc604 — Thu, 05 Feb 2015 16:13:31 +0000

New maps of ‘polarised’ light in the young Universe have revealed that the first stars formed 100 million years later than earlier estimates. ̽��ֱ��new images of cosmic background radiation, based on data released today from the European Space Agency’s Planck satellite, have shown that the process of reionisation, which ended the ‘Dark Ages’ as the earliest stars formed, started 550 million years after the Big Bang.

̽��ֱ��history of our Universe is a 13.8 billion-year tale that scientists endeavour to read by studying the planets, asteroids, comets and other objects in our Solar System, and gathering light emitted by distant stars, galaxies and the matter spread between them.

A major source of information used to piece together this story is the Cosmic Microwave Background, or CMB, the fossil light resulting from a time when the Universe was hot and dense, only 380,000 years after the Big Bang.

Thanks to the expansion of the Universe, we see this light today covering the whole sky at microwave wavelengths.

Between 2009 and 2013, the Planck satellite surveyed the sky to study this ancient light in unprecedented detail. Tiny differences in the background’s temperature trace regions of slightly different density in the early cosmos, representing the seeds of all future structure, the stars and galaxies of today.

Scientists from the Planck collaboration have published the results from the analysis of these data in a large number of scientific papers over the past two years, confirming the standard cosmological picture of our Universe with ever greater accuracy.

̽��ֱ��imaging is based on data from the Planck satellite, and was developed by the Planck collaboration, which includes the Cambridge Planck Analysis Centre at the ̽��ֱ��'s Kavli Institute for Cosmology, Imperial College London and the ̽��ֱ�� of Oxford at the London Planck Analysis Centre.

“ ̽��ֱ��CMB carries additional clues about our cosmic history that are encoded in its ‘polarisation’,” explains Jan Tauber, ESA’s Planck project scientist. “Planck has measured this signal for the first time at high resolution over the entire sky, producing the unique maps released today.”

Light is polarised when it vibrates in a preferred direction, something that may arise as a result of photons – the particles of light – bouncing off other particles. This is exactly what happened when the CMB originated in the early Universe.

Initially, photons were trapped in a hot, dense soup of particles that, by the time the Universe was a few seconds old, consisted mainly of electrons, protons and neutrinos. Owing to the high density, electrons and photons collided with one another so frequently that light could not travel any significant distant before bumping into another electron, making the early Universe extremely ‘foggy’.

Slowly but surely, as the cosmos expanded and cooled, photons and the other particles grew farther apart, and collisions became less frequent. This had two consequences: electrons and protons could finally combine and form neutral atoms without them being torn apart again by an incoming photon, and photons had enough room to travel, being no longer trapped in the cosmic fog.

̽��ֱ��new Planck data fixes the date of the end of these ‘Dark Ages’ to roughly 550 million years after the Big Bang, more than 100 million years later than previously determined by earlier polarisation observations from the NASA WMAP satellite (Planck’s predecessor), and has helped resolve a problem for observers of the early Universe.

̽��ֱ��Dark Ages lasted until the formation of the first stars and galaxies, specifically the formation of very large stars with extremely hot surfaces, which resulted in the energetic UV-radiation that began the process of reionisation of the neutral hydrogen throughout the Universe.

Very deep images of the sky from the NASA/ESA Hubble Space Telescope have provided a census of the earliest known galaxies, which started forming perhaps 300–400 million years after the Big Bang.

̽��ֱ��problem is that with a date for the end of the Dark Ages set at 450 million years after the Big Bang, astronomers can estimate that UV-radiation from such a source would have proved insufficient. “In that case, we would have needed additional, more exotic sources of energy to explain the history of reionisation,” said Professor George Efstathiou, Director of the Kavli Institute of Cosmology.

̽��ֱ��additional margin of 100 million years provided by Planck removes this need as stars and galaxies would have had the time to supply the energetic radiation required to bring the Dark Ages to a close and begin the Epoch of reionisation that would last for a further 400 million years.

Although the joint investigation between Planck and BICEP2, searching for the imprinted signature on the polarisation of the CMB of gravitational waves triggered by inflation, found no direct detection of this signal, it crucially placed strong upper-limits on the amount of primordial gravitational waves.

Searching for this signal remains a major focus of ongoing and planned CMB experiments. “ ̽��ֱ��results of the joint analysis demonstrate the power of combining CMB B-mode polarisation observations with measurements at higher frequency from Planck to clean Galactic dust,” said Dr Anthony Challinor of the Kavli Institute for Cosmology.

Inset image: Polarised emission from Milky Way dust Credit: ESA and the Planck Collaboration

New maps from the Planck satellite uncover the ‘polarised’ light from the early Universe across the entire sky, revealing that the first stars formed much later than previously thought.

We would have needed additional, more exotic sources of energy to explain the history of reionisation

George Efstathiou

ESA and the Planck Collaboration

Polarisation of the Cosmic Microwave Background

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Planck captures portrait of the young Universe, revealing earliest light

fpjl2 — Thu, 21 Mar 2013 09:44:17 +0000

After years of work, scientists have removed bright foreground emissions from the Planck satellite’s first all-sky image to reveal the Universe’s earliest light – imprinted on the sky when the Universe was just 380,000 years old – and seen today as the Cosmic Microwave Background (CMB), the relic radiation from the Big Bang.

̽��ֱ��results, released today, amount to the most detailed map of the CMB ever created, dating the Universe at 13.82 billion years old. Scientists say that Planck’s findings refine our knowledge of the Universe’s composition and evolution, and provide excellent evidence for the standard model of cosmology.

Findings also show there is nearly a fifth more dark matter in the Universe than previously thought, but less dark energy. A series of scientific papers describing the new results have been published online.

View Planck's history of the Universe here.

̽��ֱ��imaging is based on the initial 15.5 months of data from the European Space Agency’s Planck satellite, and was developed by researchers from the Cambridge Planck Analysis Centre at the ̽��ֱ��’s Kavli Institute for Cosmology, in collaboration with groups from Imperial College London and the ̽��ֱ�� of Oxford at the London Planck Analysis Centre.

̽��ֱ��Planck map of the CMB shows tiny temperature fluctuations that correspond to regions of slightly different densities at very early times, representing the seeds of all future structure - the stars and galaxies of today.

“ ̽��ֱ��CMB temperature fluctuations detected by Planck confirm once more that the relatively simple picture provided by the standard model of cosmology is an amazingly good description of the Universe,” said George Efstathiou, Professor of Astrophysics and Director of the Kavli Institute for Cosmology at the ̽��ֱ�� of Cambridge.

Efstathiou will be giving a public talk on the findings this Saturday as part of the Cambridge Science Festival, where some of the first results from the Planck satellite will be on display.

Planck gives us the most accurate values yet for ingredients that make up the Universe. Normal matter - stars and galaxies - contributes just 4.9% of the mass/energy density of the Universe.

Dark matter, which has thus far only been detected indirectly by its gravitational influence, makes up 26.8%, nearly a fifth more than previously estimated.

Conversely, dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe, accounts for slightly less than previously thought, at around 69%.

Planck data also set a new value for the rate at which the Universe is expanding today. At 67.3 km/s/Mpc, it is significantly different from relatively nearby galaxies, with the slower expansion implying the Universe is a little older than thought – 13.82 billion years.

̽��ֱ��researchers’ analysis also supports theories of ‘inflation’ – a brief but crucial early phase during the first tiny fraction of a second of the Universe’s existence. This initial expansion caused the ripples in the CMB that we see today, and explains many properties of the Universe as a whole.

While predominantly reinforcing our standard model of cosmology, the unprecedented precision of Planck’s map reveals some unexplained features that scientists say might require a new physics to be understood.

Fluctuations in the CMB over large scales do not match the standard model, an anomaly that adds to those from previous experiments such as an asymmetry in the average temperatures on opposite hemispheres of the sky.

One possible explanation might be that the Universe is in fact not the same in all directions on a larger scale than we can observe, so the light rays from the CMB may have taken a more complicated route through the Universe – resulting in some of the unusual patterns observed today.

“Our ultimate goal would be to construct a new model that predicts the anomalies and links them together. But these are early days; so far, we don’t know whether this is possible and what type of new physics might be needed. And that’s exciting,” said Efstathiou.

“By analysing these extraordinary data collected by Planck, we have been able to set the most precise constraints so far on the small number of parameters that we need to characterise the standard model,” he added.

“These range from the density of dark matter and dark energy to the speed at which the Universe is currently expanding and the relative amount of primordial fluctuations – the seeds of cosmic structures to be – on different scales.”

̽��ֱ��Cambridge Planck research team will be exhibiting and talking about their results at the Royal Society Summer Science Exhibition, 2-7 July 2013. Colleagues from the Kavli Institute for Cosmology presented work at last year’s exhibition exploring the large ground-based telescope ALMA, in the Atacama Desert of Chile.

Both the ALMA and Planck displays will be at the Kavli Institute for Cosmology as part of the Cambridge Science Festival this weekend. Dozens of free activities include talks, demonstrations and hands-on experiments for everyone to learn more about Astronomy and research at Cambridge.

Planck research scientist Professor George Efstathiou’s talk, entitled ̽��ֱ��birth of the Universe - the first results from the Planck satellite, will take place at 4pm on Saturday 23 March in the Sackler Lecture Theatre at Cambridge’s Institute of Astronomy.

Photograph of George Efstathiou courtesy of the Development Office, Credit: Nick Turpin

Satellite’s first all-sky image is the most detailed picture to date of the early Universe, giving us a better understanding of its birth.

̽��ֱ��CMB temperature fluctuations detected by Planck confirm once more that the relatively simple picture provided by the standard model of cosmology is an amazingly good description of the Universe

George Efstathiou

ESA/Planck Collaboration

Map of the cosmic microwave background

What is the Cosmic Microwave Background?

̽��ֱ��Cosmic Microwave Background (CMB) is leftover radiation from the Big Bang that fills the entire Universe - the furthest back in time we can explore using light. When the Universe was born, nearly 14 billion years ago, it was filled with hot plasma of particles (mostly protons, neutrons, and electrons) and photons (light). For roughly the first 380,000 years, the photons were constantly interacting with free electrons, meaning that they could not travel long distances - rendering the early Universe opaque, like being in fog.

As the Universe expanded, it cooled, and the fixed amount of energy within it was able to spread out over larger volumes. After about 380,000 years, it had cooled to around 3000 Kelvin (approximately 2700 ºC). At this point, electrons were able to combine with protons to form hydrogen atoms, and the temperature was too low to separate them again. In the absence of free electrons, the photons were able to move unhindered through the Universe: it became transparent.

Over the intervening billions of years, the Universe has expanded and cooled greatly. Due to the expansion of space, the wavelengths of the photons have grown - or ‘redshifted’ - to roughly 1 millimetre and their effective temperature has decreased to just 2.7 Kelvin, or around -270ºC, just above absolute zero. These photons fill the Universe today (there are roughly 400 in every cubic centimetre of space) and create a background glow that can be detected by far-infrared and radio telescopes.

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Yes

Probing the Universe: Kavli Institute for Cosmology

bjb42 — Sat, 01 May 2010 14:16:42 +0000

It may be one of Cambridge’s newest buildings but its historic roots lie in one of the ̽��ֱ��’s oldest scientific research departments. ̽��ֱ��£4 million Kavli Institute for Cosmology Cambridge (KICC), opened in 2009, is built just yards from the ̽��ֱ�� Observatory, where astronomical research has been carried out since the early 19th century. In the intervening years, Cambridge has developed an international reputation for ground-breaking discoveries about the origin, evolution and structure of the Universe, thanks to research in the Institute of Astronomy, the Department of Physics’ Cavendish Laboratory and the Department of Applied Maths and Theoretical Physics (DAMTP).

̽��ֱ��driving force for the new Institute was to bring together some of the groups from these departments, as Professor George Efstathiou, Director of KICC, explained: ‘ ̽��ֱ��spread of research across departments owes much to the natural divisions that resulted from the diverse ‘tool boxes’ used to study different areas of cosmology, such as the events following the Big Bang, the birth of stars, the structure of the Universe and so on. Today, though, there are increasing overlaps and it makes sense to integrate research programmes where there is common ground.’

KICC is now home to 55 scientists, including many graduate students from each department, and is also recruiting a new generation of research scientists: Drs George Becker, Ian McCarthy and Carrie MacTavish are the first Kavli Institute Fellows to be appointed, funded by an endowment from ̽��ֱ��Kavli Foundation to pursue independent research in Cambridge.

‘Fossil record’ of the early Universe

Where did our Universe come from? What is it made of? How is it evolving? To help answer some of the most fundamental questions about the Universe, researchers at KICC are members of international collaborations that are making use of some the most advanced scientific instruments ever constructed – satellites such as the £1.7 billion Planck and Herschel Observatories launched by the European Space Agency last year. Such instruments will provide insight into events that happened billions of years ago – the Universe’s unique ‘fossil record’ – by analysing the light emitted in the distant past but which is only reaching us now.

‘ ̽��ֱ��furthest back we can currently detect corresponds to light that was emitted 300,000 years after the Big Bang, just under 13.7 billion years ago, when the Universe was as hot as the surface of the Sun,’ explained Professor Anthony Lasenby, Deputy Director of KICC. ‘When it was emitted, it was visible light, but because the Universe has expanded by a factor of over a thousand, it has stretched out and become cosmic microwave background radiation.’ ̽��ֱ��Planck satellite will measure tiny fluctuations in the radiation with the highest accuracy ever achieved.

Working in partnership with over 40 institutes as part of the pan-European Planck collaboration, Cambridge scientists have been part of the satellite’s scientific programme since its inception in 1993, and are now involved in analysing and interpreting the vast amounts of data delivered back to Earth. ̽��ֱ��satellite will complete a full scan of the whole sky every six months until the end of 2011, providing information to test theories of the early Universe and the origin of cosmic structure.

Shifting into the red

After the Big Bang, the first stars are thought to have formed out of a network of matter that grew from the tiny fluctuations seen in the cosmic microwave background. Dr Martin Haehnelt, Dr George Becker and others at KICC are studying the composition of this network, which is known as the intergalactic medium. ‘ ̽��ֱ��energy released from the first stars would have had a dramatic impact on the medium around them, changing the way future stars and galaxies would form,’ Dr Becker explained. ‘We can study the intergalactic medium from when the Universe was about a billion years old through to the present, but we’d like to go even earlier, closer to the Big Bang, because it contains the fingerprint of the initial and changing conditions needed to form what we see today.’

To do this, cosmologists are looking at the high-redshift Universe. As the Universe expands, light produced by distant stars and galaxies is stretched to longer wavelengths, changing the apparent colour of the light: the more distant the object, the redder its light becomes by the time it reaches Earth. As a result, highly redshifted objects trace the earliest phases of the Universe’s evolution. Using the ̽��ֱ��’s Darwin supercomputer, Dr Becker is analysing data showing the thermal and gaseous history of the Universe to understand the ingredients needed for galaxy formation.

Researchers at the Kavli are also studying the high-redshift Universe in order to catch first sight of young galaxies. By searching the sky at unprecedented levels of sensitivity, a team led by Dr Haehnelt has discovered very faint traces of long-searched-for galaxies.

Radio telescopes of the future

Kavli scientist Dr John Richer is the UK Project Scientist for ALMA, the Atacama Large Millimetre Array, a huge radio telescope sited in the Atacama Desert of northern Chile. ALMA is the result of collaboration between 17 countries worldwide. When completed in 2013, it will provide the first detailed images of the gaseous component of high-redshift galaxies; in addition, it will map the structure of the discs of material that surround newly formed stars in which planetary systems are known to form. To do this, ALMA will combine data from 66 radio antennas to construct a telescope with an effective diameter of 10 miles, using the technique of aperture synthesis that won Cambridge astronomers Sir Martin Ryle and Professor Antony Hewish the 1974 Nobel Prize in Physics.

Meanwhile, a Cambridge team led by Dr Paul Alexander is providing crucial input into the science, design and costing of the Square Kilometre Array (SKA) radio telescope; Dr Alexander leads the UK technical work on the SKA design, heading a team split between Cambridge, Manchester and Oxford. Construction of the first phase of the instrument is expected in 2015, with completion in 2020. Dr Alexander explained the importance of this new development: ‘ ̽��ֱ��SKA will be 100 times more sensitive than the radio telescopes of the present generation, and will be able to survey the sky up to one million times faster. This will enable us to probe the so-called ‘dark ages’ of the Universe before thefirst stars shed light, observe the formation of galaxies, test theories of gravity and study the role of cosmic magnetism.’

Writing the history of the Universe

̽��ֱ��scientific goals of KICC are ambitious: ‘ ̽��ֱ��concept of reconstructing, in three dimensions, events that happened over a time span of nearly 14 billion years is no longer just a dream,’ said Professor Efstathiou. ‘Working with the international community, and as part of the wider Kavli family of 15 institutes worldwide, we hope to make dramatic discoveries about the history, fabric and evolution of the Universe as we reach further into the sky.’

For more information about research at the Kavli Institute for Cosmology, please visit www.kicc.cam.ac.uk/

Scientists at Cambridge’s Kavli Institute are studying how the Universe developed after the Big Bang by analysing light emitted up to 13.7 billion years ago.

̽��ֱ��concept of reconstructing, in three dimensions, events that happened over a time span of nearly 14 billion years is no longer just a dream.

Professor George Efstathiou

ESA and the HFI consortium; Axel Mellinger

Region mapped by Planck satellite

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Yes

Cambridge research to explore the origins of the universe

bjb42 — Fri, 15 May 2009 00:00:00 +0000

Aboard the rocket are the Planck and Herschel Observatories, worth a combined £1.7bn, which will scan the sky looking for new information about the history of the universe.

̽��ֱ��Planck spacecraft project, in which Cambridge researchers have taken a leading role, started life 16 years ago as a proposal to the European Space Agency. Since then many engineers and scientists have worked hard to create a satellite now on its way to an orbit around the second Sun-Earth Lagrangian point, situated around 1.5 million km from Earth in the opposite direction to the sun.

̽��ֱ��Planck spacecraft, named after the German Nobel Laureate Max Planck, aims to answer some the biggest questions about the universe:

Why is the universe so big?
What happened at the big bang?
Why is the universe so old?

To achieve this, Planck will map the sky looking at incredibly long wavelengths of light - in the microwave part of the electromagnetic spectrum.

It will be able to take incredibly detailed measurements of what is known as the Cosmic Microwave Background. ̽��ֱ��CMB is the remnant radiation of the Big Bang that has cooled down as the universe has expanded and now has a temperature of 2.725 degrees above absolute zero.

Within the CMB there are temperature variations in the ancient heat energy that can give the scientists insight into the early structure of the universe.

̽��ֱ��Cambridge Planck Anlysis Centre, led by Professor George Efstathiou, will be actively involved in the analysis and scientific interpretation of the data sent back from Planck. They will turn the signals sent back from Planck into the CMB signal as well as be responsible for providing a catalogue of many hundreds of galaxy clusters which will be used to constrain the nature of the mysterious dark energy that is causing the universe to accelerate.

They will also play a major part in several of Planck's flagship science projects such as constraining the physics of the early universe, mapping the distribution of dark matter, and determining to unprecedented precision the composition of the universe.

Professor Efstathiou told the BBC: "We will be probing regimes that have never been studied before where the physics is very, very uncertain."

He continued: "It's possible we could find a signature from before the Big Bang; or it's possible we could find the signature of another universe and then we'd have experimental evidence that we are part of a multiverse. There is a mixture of serenity - because we have done every test that we can do - but also anxiety - because it is always risky to launch such satellites towards deep space."

Photo: ESA - D. Ducros

Cambridge ̽��ֱ�� researchers are casting their gaze back to the start of the universe following the launch last week of two of the most expensive scientific satellites ever built by the European Space Agency.

It's possible we could find a signature from before the Big Bang; or it's possible we could find the signature of another universe and then we'd have experimental evidence that we are part of a multiverse.

Professor George Efstathiou

Mollenborg from Flickr

Into Space

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Yes