ESA Planck Telescope: Sky Survey changes date on early stars

Planck has mapped the delicate polarisation of the CMB across the entire sky

Scientists working on ESA's Planck satellite say the first stars in the Universe lit up later than was previously thought.

The team has made the most precise map of the "oldest light" in the cosmos.

Earlier observations of this radiation had suggested that the first generation of stars burst into life about 420 million years after the Big Bang.

The new Planck data now indicates they fired up around 560 million years after the Universe got going.

"This difference of 140 million years might not seem that significant in the context of the 13.8-billion-year history of the cosmos, but proportionately it's actually a very big change in our understanding of how certain key events progressed at the earliest epochs," said Prof George Efstathiou, one of the leaders of the Planck Science Collaboration.

Subtle signal
The assessment is based on studies of the "afterglow" of the Big Bang, the ancient light called the Cosmic Microwave Background (CMB), which still washes over the Earth today.

The European Space Agency's (ESA) Planck satellite mapped this "fossil" between 2009 and 2013.

It contains a wealth of information about early conditions in the Universe, and can even be used to work out its age, shape and do an inventory of its contents.

Scientists can also probe it for very subtle "distortions" that tell them about any interactions the CMB has had on its way to us.

Forging elements
One of these would have been imprinted when the infant cosmos underwent a major environmental change known as re-ionisation.

It is when the cooling neutral hydrogen gas that dominated the Universe in the aftermath of the Big Bang was then re-energised by the ignition of the first stars.

These hot giants would have burnt brilliant but brief lives, producing the very first heavy elements. But they would also have "fried" the neutral gas around them - ripping electrons off the hydrogen protons.

And it is the passage of the CMB through this maze of electrons and protons that would have resulted in it picking up a subtle polarisation.

Impression: The first stars would have been unwieldy behemoths that burnt brief but brilliant lives

The Planck team has now analysed this polarisation in fine detail and determined it to have been generated at 560 million years after the Big Bang.

The American satellite WMAP, which operated in the 2000s, made the previous best estimate for re-ionisation at 420 million years.

The problem with that number was that it sat at odds with Hubble Space Telescope observations of the early Universe.

Hubble could not find stars and galaxies in sufficient numbers to deliver the scale of environmental change at the time when WMAP suggested it was occurring.

Planck's new timing "effectively solves the conflict," commented Prof Richard McMahon from Cambridge University, UK.

"We had two groups of astronomers who were basically working on different sides of the problem. The Planck people came at it from the Big Bang side, while those of us who work on galaxies came at it from the 'now side'.

"It's like a bridge being built over a river. The two sides do now join where previously we had a gap," he told reporters.

That gap had prompted scientists to invoke complicated scenarios for how re-ionisation could have occurred, including the ideas that there were an even earlier population of giant stars or energetic black holes. Such solutions are no longer needed.

The finding is also good news for the next generation of observatories like the James Webb Space Telescope, which will have the power to see right through the epoch of re-ionisation.

CIBER: Caltech rocket experiment finds surprising cosmic light

The entrance of the CIBER optics, showing two near-infrared wide-field cameras (top), an absolute spectrometer (lower left) and a Fraunhofer line spectrometer (lower right). 

Credit: Jamie Bock/Caltech

Using an experiment carried into space on a NASA suborbital rocket, astronomers at Caltech and their colleagues have detected a diffuse cosmic glow that appears to represent more light than that produced by known galaxies in the universe.

The researchers, including Caltech Professor of Physics Jamie Bock and Caltech Senior Postdoctoral Fellow Michael Zemcov, say that the best explanation is that the cosmic light originates from stars that were stripped away from their parent galaxies and flung out into space as those galaxies collided and merged with other galaxies.

This explanation is described in a paper published November 7 in the journal Science,

The discovery suggests that many such previously undetected stars permeate what had been thought to be dark spaces between galaxies, forming an interconnected sea of stars.

"Measuring such large fluctuations surprised us, but we carried out many tests to show the results are reliable," says Zemcov, who led the study.

Although they cannot be seen individually, "the total light produced by these stray stars is about equal to the background light we get from counting up individual galaxies," says Bock, also a senior research scientist at JPL.

Bock is the principal investigator of the rocket project, called the Cosmic Infrared Background Experiment (CIBER), which originated at Caltech and flew on four rocket flights from 2009 through 2013.

In earlier studies, NASA's Spitzer Space Telescope, which sees the universe at longer wavelengths, had observed a splotchy pattern of infrared light called the cosmic infrared background.

The splotches are much bigger than individual galaxies.

"We are measuring structures that are grand on a cosmic scale," says Zemcov, "and these sizes are associated with galaxies bunching together on a large-scale pattern."

Initially some researchers proposed that this light came from the very first galaxies to form and ignite stars after the Big Bang.

Others, however, have argued the light originated from stars stripped from galaxies in more recent times.

CIBER was designed to help settle the debate. "CIBER was born as a conversation with Asantha Cooray, a theoretical cosmologist at UC Irvine and at the time a postdoc at Caltech with [former professor] Marc Kamionkowski," Bock explains.

"Asantha developed an idea for studying galaxies by measuring their large-scale structure. Galaxies form in dark-matter halos, which are over-dense regions initially seeded in the early universe by inflation.

Furthermore, galaxies not only start out in these halos, they tend to cluster together as well. Asantha had the brilliant idea to measure this large-scale structure directly from maps.

Experimentally, it is much easier for us to make a map by taking a wide-field picture with a small camera, than going through and measuring faint galaxies one by one with a large telescope."

More information: On the Origin of Near-Infrared Extragalactic Background Light Anisotropy, Science, www.sciencemag.org/lookup/doi/… 1126/science.1258168

Cosmic rays Hotspot: Physicists closer to finding the mysterious sources

This map of the northern sky shows cosmic ray concentrations, with a "hotspot" with a disproportionate number of cosmic rays shown as the bright red and yellow spot, upper right. 

An international team of physicists using the University of Utah-operated Telescope Array near Delta, Utah, say their discovery of the hotspot should narrow the search for the mysterious source or sources of ultrahigh-energy cosmic rays, which carry more energy than any other known particle in the universe. 

Credit: Kazumasa Kawata, University of Tokyo Institute for Cosmic Ray Research.

An observatory run by the University of Utah found a "hotspot" beneath the Big Dipper emitting a disproportionate number of the highest-energy cosmic rays.

The discovery moves physics another step toward identifying the mysterious sources of the most energetic particles in the universe.

Gordon Thomson

"This puts us closer to finding out the sources, but no cigar yet," says University of Utah physicist Gordon Thomson, spokesman and co-principal investigator for the $25 million Telescope Array cosmic ray observatory west of Delta, Utah; the Northern Hemisphere's largest cosmic ray detector.

"All we see is a blob in the sky, and inside this blob there is all sorts of stuff – various types of objects, that could be the source" of the powerful cosmic rays, he adds. "Now we know where to look."

A new study identifying a hotspot in the northern sky for ultrahigh-energy cosmic rays has been accepted for publication by Astrophysical Journal Letters.

Thomson says many astrophysicists suspect ultrahigh-energy cosmic rays are generated by active galactic nuclei (AGNs), in which material is sucked into a supermassive black hole at the center of galaxy, while other material is spewed away in a beam-like jet known as a blazar.

Another popular possibility is that the highest-energy cosmic rays come from some supernovas (exploding stars) that emit gamma rays bursts.

Lower-energy cosmic rays come from the sun, other stars and exploding stars, but the source or sources of the most energetic cosmic rays has been a decades-long mystery.

The study was conducted by 125 researchers in the Telescope Array project, including Thomson and 31 other University of Utah physicists, plus 94 other scientists from the University of Tokyo (ICRR) and 28 other research institutions in Japan, the United States, South Korea, Russia and Belgium.

Read the full article here

More Information: Indications of Intermediate-Scale Anisotropy of Cosmic Rays with Energy Greater Than 57 EeV in the Northern Sky Measured with the Surface Detector of the Telescope Array Experiment - Authors: K. Kawata, et al.

BOSS quasars track the expanding universe with precision

An artist's conception of how BOSS uses quasars to measure the distant universe. 

Light from distant quasars is partly absorbed by intervening gas, which is imprinted with a subtle ring-like pattern of known physical scale. 

Astronomers have now measured this scale with an accuracy of two percent, precisely measuring how fast the universe was expanding when it was just 3 billion years old. 

Credit: Zosia Rostomian, Lawrence Berkeley National Laboratory, and Andreu Font-Ribera, BOSS Lyman-alpha team, Berkeley Lab.

The Baryon Oscillation Spectroscopic Survey (BOSS), the largest component of the third Sloan Digital Sky Survey (SDSS-III), pioneered the use of quasars to map density variations in intergalactic gas at high redshifts, tracing the structure of the young universe.

BOSS charts the history of the universe's expansion in order to illuminate the nature of dark energy, and new measures of large-scale structure have yielded the most precise measurement of expansion since galaxies first formed.

The latest quasar results combine two separate analytical techniques. A new kind of analysis, led by physicist Andreu Font-Ribera of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and his team, was published late last year.

Analysis using a tested approach, but with far more data than before, has just been published by Timothée Delubac, of EPFL Switzerland and France's Centre de Saclay, and his team.

The two analyses together establish the expansion rate at 68 kilometers per second per million light years at redshift 2.34, with an unprecedented accuracy of 2.2 percent.

"This means if we look back to the universe when it was less than a quarter of its present age, we'd see that a pair of galaxies separated by a million light years would be drifting apart at a velocity of 68 kilometers a second as the universe expands," says Font-Ribera, a postdoctoral fellow in Berkeley Lab's Physics Division.

"The uncertainty is plus or minus only a kilometer and a half per second." Font-Ribera presented the findings at the April 2014 meeting of the American Physical Society in Savannah, GA.

BOSS employs both galaxies and distant quasars to measure baryon acoustic oscillations (BAO), a signature imprint in the way matter is distributed, resulting from conditions in the early universe.

While also present in the distribution of invisible dark matter, the imprint is evident in the distribution of ordinary matter, including galaxies, quasars, and intergalactic hydrogen.

"Three years ago BOSS used 14,000 quasars to demonstrate we could make the biggest 3-D maps of the universe," says Berkeley Lab's David Schlegel, principal investigator of BOSS.

"Two years ago, with 48,000 quasars, we first detected baryon acoustic oscillations in these maps. Now, with more than 150,000 quasars, we've made extremely precise measures of BAO."

The BAO imprint corresponds to an excess of about five percent in the clustering of matter at a separation known as the BAO scale.

Recent experiments including BOSS and ESA's Planck satellite study of the cosmic microwave background put the BAO scale, as measured in today's universe, at very close to 450 million light years, a "standard ruler" for measuring expansion.

BAO directly descends from pressure waves (sound waves) moving through the early universe, when particles of light and matter were inextricably entangled; 380,000 years after the big bang, the universe had cooled enough for light to go free.

The cosmic microwave background radiation preserves a record of the early acoustic density peaks; these were the seeds of the subsequent BAO imprint on the distribution of matter.

More information: "Quasar-Lyman α Forest Cross-Correlation from BOSS DR11: Baryon Acoustic Oscillations," by Andreu Font-Ribera, et al., has been submitted to the Journal of Cosmology and Astropartical Physics and is now available online at arxiv.org/abs/1311.1767.

ESA Planck and NASA WMAP: Dark energy a mirage concealed behind phantom fields

Observations of ESA's Planck and NASA's WMAP satellites help to solve the equation of the state of dark energy. 

Credit: ESA et al.

Quintessence and phantom fields, two hypotheses formulated using data from satellites, such as ESA's Planck and NASA's Wilkinson Microwave Anisotropy Probe (WMAP), are among the many theories that try to explain the nature of dark energy.

Now researchers from Barcelona and Athens suggest that both possibilities are only a mirage in the observations and it is the quantum vacuum which could be behind this energy that moves our universe.

Cosmologists believe that some three quarters of the universe are made up of a mysterious dark energy which would explain its accelerated expansion.

The truth is that they do not know what it could be, therefore they put forward possible solutions.

One is the existence of quintessence, an invisible gravitating agent that instead of attracting, repels and accelerates the expansion of the cosmos.

WMAP Satellite Diagram

From the Classical World until the Middle Ages, this term has referred to the ether or fifth element of nature, together with earth, fire, water and air.

Another possibility is the presence of an energy or phantom field whose density increases with time, causing an exponential cosmic acceleration.

This would reach such speed that it could break the nuclear forces in the atoms and end the universe in some 20,000 million years, in what is called the Big Rip.

The experimental data that underlie these two hypotheses comes from satellites such as ESA's Planck and NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

Observations from the two probes are essential for solving the so-called equation of the state of dark energy, a characterising mathematical formula, the same as that possessed by solid, liquid and gaseous states.

Now researchers from the University of Barcelona (Spain) and the Academy of Athens (Greece) have used the same satellite data to demonstrate that the behaviour of dark energy does not need to resort to either quintessence or phantom energy in order to be explained.

The details have been published in the Monthly Notices of the Royal Astronomical Society journal.

Joan Solà

"Our theoretical study demonstrates that the equation of the state of dark energy can simulate a quintessence field, or even a phantom field, without being one in reality, thus when we see these effects in the observations from WMAP, Planck and other instruments, what we are seeing is an mirage," told SINC Joan Solà, one of the authors from University of Barcelona.

Nothing fuller than the quantum vacuum
"What we think is happening is a dynamic effect of the quantum vacuum, a parameter that we can calculate," explained the researcher.

The concept of the quantum vacuum has nothing to do with the classic notion of absolute nothingness.

"Nothing is more 'full' than the quantum vacuum since it is full of fluctuations that contribute fundamentally to the values that we observe and measure," Solà pointed out.

The detailed, all-sky picture of the infant universe created from nine years of WMAP data. 

The image reveals 13.77 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. 

The signal from our galaxy was subtracted using the multi-frequency data. This image shows a temperature range of ± 200 microKelvin.

Credit: NASA / WMAP Science Team

These scientists propose that dark energy is a type of dynamical quantum vacuum energy that acts in the accelerated expansion of our universe.

This is in contrast to the traditional static vacuum energy or cosmological constant.

The drawback with this strange vacuum is that it is the source of problems such as the cosmological constant, a discrepancy between the theoretical data and the predictions of the quantum theory that drives physicists mad.

"However, quintessence and phantom fields are still more problematic, therefore the explanation based on the dynamic quantum vacuum could be the more simple and natural one," concluded Solà.

More information: Spyros Basilakos, Joan Sola. "Effective equation of state for running vacuum: "mirage" quintessence and phantom dark energy". Monthly Notices of the Royal Astronomical Society 437(4), February 2014. DOI: 10.1093/mnras/stt2135

Rumours that Gravitational waves have been detected

This detailed map of the Cosmic Microwave Background (CMB) is created from seven years worth of data. 

The colour variations correspond to temperature variations in the young universe: the seeds for stars and galaxies observed today. 

Credit: NASA

Last week the Harvard-Smithsonian Center for Astrophysics (CfA) stated rather nonchalantly that they will be hosting a press conference on Monday, March 17th, to announce a "major discovery."

Without a potential topic for journalists to muse on, this was as melodramatic as it got but then the Guardian posted an article on the subject and the rumours went into overdrive.

The speculation is this: a U.S. team is on the verge of confirming they have detected primordial gravitational waves—ripples in the fabric of spacetime that carry echoes of the big bang nearly 14 billion years ago.

If there is evidence for gravitational waves, it will be a landmark discovery, ultimately changing the face of physics.

Not only are gravitational waves the last untested prediction of Albert Einstein's General Theory of Relativity, but primordial gravitational waves will allow astronomers to glimpse the universe in its infancy.

"It's been called the Holy Grail of cosmology," Hiranya Peiris, a cosmologist from University College London, told reporters.

"It would be a real major, major, major discovery." Any convincing evidence would almost certainly lead to a Nobel prize.

The signal is rumoured to have been found by a telescope known as BICEP (Background Imaging of Cosmic Extragalactic Polarization), which scans the sky from the south pole, looking for a subtle effect in the Cosmic Microwave Background (CMB): the radiation released 380,000 years after the big bang when space became transparent to light and photons were allowed to travel freely across the universe.

The South Pole Telescope (left) and BICEP (right). Credit: Dana Hrubes

While the CMB has been mapped in exquisite detail, astronomers think that hidden within the map is a second fingerprint, which would reveal gravitational waves.

Its radiation was scattered toward us from the universe's earliest atoms, similar to the way blue light is scattered toward us from the atoms in the sky and just as the sky is slightly polarized, the waves have a preferred orientation, so is the CMB (on the level of a few percent).

Cosmologists are digging through the data, searching for a subtle twist in the polarized light, known as B-modes.

If a gravitational wave moves through the fabric of spacetime, it will squeeze spacetime in one direction (the universe will look a little hotter) and stretch it in another (the universe will look a little cooler).

The photons will scatter with a preferred direction, leaving a slightly polarized imprint on the CMB, due to the passing gravitational wave.

Andrew Jaffe

"If a detection has been made, it is extraordinarily exciting," Andrew Jaffe, a cosmologist from Imperial College, London, told reporters.

"This is the real big tick-box that we have been waiting for. It will tell us something incredibly fundamental about what was happening when the universe was only 10-34 seconds old."

Massive neutrinos solve a cosmological conundrum

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

The UK team, from the universities of Manchester and Nottingham, 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.

Planck spacecraft

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.

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.

Professor Richard Battye, from the University of Manchester'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."

Cosmic Microwave Background (CMB)

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).

Adam Moss

In this paper, Professor Battye and co-author Dr Adam Moss, from the University of Nottingham, 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).

Dr Moss said: "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."

More Information: 'Evidence for Massive Neutrinos from Cosmic Microwave Background and Lensing Observations' DOI:10.1103/PhysRevLett.112.051303

ESA Herschel throws new light on oldest cosmic light

photons in the Cosmic Microwave Background (CMB)

This illustration shows how photons in the Cosmic Microwave Background (CMB) are deflected by the gravitational lensing effect of massive cosmic structures as they travel across the Universe. 

Using data from ESA's Planck satellite, cosmologists have been able to measure this gravitational lensing of the CMB over the whole sky for the first time. 

Credit: ESA and the Planck Collaboration

Cosmologists have achieved a first detection of a long-sought component in the Cosmic Microwave Background (CMB).

This component, known as B-mode polarisation, is caused by gravitational lensing, the bending of light by massive structures as it travels across the Universe.

The result is based on the combination of data from the South Pole Telescope and ESA's Herschel Space Observatory.

This detection is a milestone along the way to the possible discovery of another kind of B-mode signal in the polarised CMB - a signal produced by gravitational waves less than a second after the Universe began.

The Cosmic Microwave Background is the most ancient light that has travelled almost unimpeded across the Universe, and it contains a wealth of information about the origin and nature of the cosmos.

During their journey, photons from the CMB have encountered a multitude of galaxies and galaxy clusters and have been deflected by these large concentrations of matter.

This phenomenon, known as gravitational lensing, imprints a subtle distortion on the pattern of the CMB that encodes details about the large-scale distribution of structure in the Universe.

In recent years, cosmologists have detected the signature of gravitational lensing on the CMB temperature using data from ground-based and space-borne experiments, including the first all-sky image of this effect achieved using ESA's Planck satellite.

A small portion of the CMB is polarised, and gravitational lensing also affects this part of the signal. In fact, the polarised CMB is an additional and even richer treasure trove than the unpolarised signal to use to explore the Universe's past.

Now a team of cosmologists studying the polarised CMB has detected in it the signature of gravitational lensing, opening new and exciting possibilities to study the distribution of matter across the cosmos.

This result is also the first detection of the elusive second component of the CMB polarisation – the long-sought B-modes.

The study is based on the combination of data from SPTpol, the polarisation-sensitive receiver on the National Science Foundation's South Pole Telescope (SPT), and the SPIRE instrument on board ESA's Herschel Space Observatory.

The SPT is a ground-based telescope, located in Antarctica, to observe the CMB to very high angular resolution in a small patch of the southern sky.

Planck Microwave Background Radiation: Seeing the Big Bang

Two Cosmic Microwave Background anomalies hinted at by the Planck observatory's predecessor, NASA's WMAP, are confirmed in new high-precision data revealed on March 21, 2013. 

In this image, the two anomalous regions have been enhanced with red and blue shading to make them more clearly visible.

Credit: ESA and the Planck Collaboration

The universe burst into existence 13.8 billion years ago in a "Big Bang" that blew space up like a giant balloon. For nearly 400,000 years after that, the universe remained a seething-hot, opaque fog of plasma and energy.

But then, in an epoch known as recombination, the temperature dropped enough to allow the formation of electrically neutral atoms, turning the universe transparent.

Photons began to travel freely, and the light we know as the cosmic microwave background (CMB) pervaded the heavens, filled with clues about the first few moments after creation.

John Mather

"As far as we know, that's as far [back] as we can see — we get an image of the universe as it was when it was about 389,000 years old," said John Mather of NASA's Goddard Space Flight Center in Greenbelt, Md., senior project scientist for the space agency's James Webb Space Telescope, the successor to the Hubble Space Telescope.

Mather and George Smoot won the 2006 Nobel Prize in Physics for their work on NASA's Cosmic Background Explorer satellite mission.

"We believe — although it's not 100 percent proven — that spots that we see in the microwave map from when the universe was 389,000 years old were actually imposed on it when [the universe] was sub-microseconds old," Mather told reporters.

"There's an interpretive step there, but it's probably right."

The CMB, which was first detected in 1964, is strikingly uniform. But COBE discovered in 1992 that it's studded with tiny temperature fluctuations. These variations have since been mapped out more precisely by two other space missions, NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and the ESA European Planck spacecraft.

The hot and cold areas — which differ from their homogeneous surroundings at a level of just 1 part per 100,000 — signify areas featuring different densities.

"You can imagine a cold spot being a gravitational overdensity; it's sitting at the bottom of a shallow gravity well," said Al Kogut of NASA Goddard, who has worked on COBE, WMAP and other efforts to map the CMB.

Exquisite Cosmic Map Hints at Universe's Birth

This map shows the oldest light in our universe, as detected with the greatest precision yet by the Planck mission. 

The ancient light, called the cosmic microwave background, was imprinted on the sky when the universe was 370,000 years old. 

It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the seeds of all future structure: the stars and galaxies of today. Image released March 21, 2013.

CREDIT: ESA and the Planck Collaboration

Charles Lawrence

"We have the best map ever of the cosmic microwave background, and that shows us what the universe was like 370,000 years after the Big Bang," said Charles Lawrence, a scientist at NASA's Jet Propulsion Laboratory in California who is the lead U.S. scientist on the Planck project. Lawrence and other researchers summed up the consequences of the meeting, called the Davis Cosmic Frontiers Conferences, in a call to reporters Friday (May 24).

The cosmic microwave background (CMB) was first discovered in 1964, and since then a series of experiments, culminating in Planck, have measured it in increasing detail, providing cosmologists a direct line to test theories about the beginnings of the universe.

Planck launched in 2009, and the recent data represent the product of the spacecraft's first 15.5 months of observations.

Andreas Albrecht

"Rarely in the history of science has there been such a triumphant transformation from really complete ignorance to really deep insights in just a few decades," said Andreas Albrecht, chair of the University of California, Davis Department of Physics.

ESA Planck satellite: Maps detail Universe's ancient light

The map shows tiny deviations from the average background temperature, where blue is slightly cooler and red is slightly warmer. 

The cold spots are where matter was more concentrated and later collapsed under gravity to form stars and galaxies. 

Image: ESA/Planck Collaboration

A spectacular new map of the "oldest light" in the sky has just been released by the European Space Agency.

Scientists say its mottled pattern is an exquisite confirmation of our Big-Bang model for the origin and evolution of the Universe.
But there are features in the picture, they add, that are unexpected and will require ideas to be refined.

The map was assembled from 15 months' worth of data acquired by the 600m-euro (£515m) Planck space telescope.

It details what is known as the cosmic microwave background, or CMB - a faint glow of microwave radiation that pervades all of space.

Its precise configuration, visible in the new Planck data, is suggestive of a cosmos that is slightly older than previously thought - one that came into existence 13.82 billion years ago.

This is an increase of about 50 million years on earlier calculations.

The map's pattern also indicates a subtle adjustment is needed to the Universe's inventory of contents.

It seems there is slightly more matter out there (31.7%) and slightly less "dark energy" (68.3%), the mysterious component thought to be driving the cosmos apart at an accelerating rate.

Planck is the third western satellite to study the CMB. The two previous efforts - COBE and WMAP - were led by the US space agency (Nasa). The Soviets also had an experiment in space in the 1980s that they called Relikt-1.

• The CMB's temperature fluctuations are put through a number of statistical analyses
• Deviations can be studied as a function of their size on the sky - their angular scale
• When compared to best-fit Big Bang models, some anomalies are evident
• One shows the fluctuations on the biggest scales to be weaker than expected
• Theorists will need to adjust their ideas to account for these features

The CMB is the light that was finally allowed to spread out across space once the Universe had cooled sufficiently to permit the formation of hydrogen atoms - about 380,000 years into the life of the cosmos.

It still bathes the Earth in a near-uniform glow at microwave frequencies, and has a temperature profile that is just 2.7 degrees above absolute zero.

But it is possible to detect minute deviations in this signal, and these fluctuations - seen as mottling in the map - are understood to reflect the differences in the density of matter when the light parted company and set out on its journey all those years ago

The fluctuations can be thought of as the seeds for all the structure that later developed in the cosmos - all the stars and galaxies

Scientists subject the temperature deviations to a range of statistical analyses, which can then be matched against theoretical expectations.

This allows them to rule in some models to explain the origin and evolution of the cosmos, while ruling out a host of others.

The team that has done this for Planck's data says the map is an elegant fit for the standard model of cosmology - the idea that the Universe started in a hot, dense state in an incredibly small space, and then expanded and cooled.

At a fundamental level, it also supports an "add-on" to this Big Bang theory known as inflation, which postulates that in the very first moments of its existence the Universe opened up in an exponential manner - faster than light itself.

But because Planck's map is so much more detailed than anything previously obtained, it is also possible to see some anomalies in it.

Cosmic Background radiation (CMB): No evidence for 'knots' in space

The new study, published in Physical Review Letters, places the best limits available on theories that produce textures, ruling out at 95% confidence theories that produce more than six detectable textures on our sky.

Theories of the primordial Universe predict the existence of knots in the fabric of space - known as cosmic textures - which could be identified by looking at light from the cosmic microwave background (CMB), the relic radiation left over from the Big Bang.

Using data from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite, researchers from UCL, Imperial College London and the Perimeter Institute have performed the first search for textures on the full sky, finding no evidence for such knots in space.

As the Universe cooled it underwent a series of phase transitions, analogous to water freezing into ice. Many transitions cannot occur consistently throughout space, giving rise in some theories to imperfections in the structure of the cooling material known as cosmic textures.

If produced in the early Universe, textures would interact with light from the CMB to leave a set of characteristic hot and cold spots.

If detected, such signatures would yield invaluable insight into the types of phase transitions that occurred when the Universe was a fraction of a second old, with drastic implications for particle physics.

A previous study, published in Science in 2007, provided a tantalising hint that a CMB feature known as the "Cold Spot" could be due to a cosmic texture. However, the CMB Cold Spot only comprises around 3% of the available sky area, and an analysis using the full microwave sky had not been performed.

The new study, published in Physical Review Letters, places the best limits available on theories that produce textures, ruling out at 95% confidence theories that produce more than six detectable textures on our sky.

Stephen Feeney, from the UCL Department of Physics and Astronomy and lead author, said: "If textures were observed, they would provide invaluable insight into the way nature works at tremendous energies, shedding light on the unification of the physical forces.

"The tantalizing hints found in a previous small-scale search meant it was extremely important to carry out this full-sky analysis."

Co-author Matt Johnson, from the Perimeter Institute, Canada, said: "Although there is no evidence for these objects in the WMAP data, this is not the last word: in a few months we will have access to much better data from the Planck satellite.

"Whether we find textures in the Planck data or further constrain the theories that produce them, only time will tell!"
 
"A robust constraint on cosmic textures from the cosmic microwave background" is published in the journal Physical Review Letters on 12 June 2012.