Thursday, March 21, 2013

The Universe's Baby Pictures, New Age Date Is 13.82 Billion Years


Europe’s Planck satellite - a flagship mission for the UK Space Agency - has compiled the most detailed map ever created of the cosmic microwave background (the relic radiation from the Big Bang). The new map refines our understanding of the Universe’s composition and evolution, and unveils new features that could challenge the foundations of our current understanding of its evolution.
"We are very excited, we are finally seeing the concrete results of so many years of hard work". This is how the scientists of the Planck project have commented the first data resulting from the observations carried out by Planck. The mission of the ESA satellite is to observe the past of our Universe, going back in time and reaching the very first instant right after the Big Bang. The image that the Planck scientists convey today is that of a 'child' Universe, dating back to about 380,000 years after the Big Bang, when its temperature was similar to that of the most external layer of a star today.

Planck refines our knowledge of the Universe’s composition and evolution New maps provide excellent evidence for our standard model of cosmology Planck dates Universe at 13.82 billion years old
Anomalies suggest that Universe may be different on scales larger than those we can directly observe
Most accurate values yet for the ingredients of the Universe, with normal matter contributing just 4.9% of the mass/energy density of the Universe and dark matter making up 26.8% - nearly a fifth more than the previous estimate.

Cosmic microwave background seen by Planck.
(JPG, 6.8 Mb)  Credit: ESA and the Planck Collaboration.

The image is based on the initial 15.5 months of data from Planck and is the mission’s first all-sky picture of the oldest light in our Universe, imprinted on the sky when it was just 380 000 years old. This cosmic microwave background (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.

Overall, the information extracted from Planck’s new map provides an excellent confirmation of the standard model of cosmology at an unprecedented accuracy, setting a new benchmark for our knowledge of the contents of the Universe.



Dr Chris Castelli, Acting Director of Science, Technology and Exploration at the UK Space Agency, said, "We're immensely proud to be playing a key role in this amazing discovery. With its ability to make such detailed and accurate observations, Planck is helping us to place the vital pieces of a jigsaw that could give us a full picture of the evolution of our Universe, rewriting the textbooks along the way."

“The CMB temperature fluctuations detected by Planck confirm once more that the relatively simple picture provided by the standard model is an amazingly good description of the Universe,” explains George Efstathiou of the University of Cambridge, UK.

(JPG, 341 Kb) 
The properties of the hot and cold regions of the map provide information about the composition and evolution of the Universe. Normal matter that makes up 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 the previous estimate. 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%.

The Planck data also set a new value for the rate at which the Universe is expanding today, known as the Hubble constant. At 67.3 km/s/Mpc, this is significantly different from the value measured from relatively nearby galaxies. This somewhat slower expansion implies that the Universe is also a little older than previously thought, at 13.8 billion years.

The analysis also gives strong support for theories of “inflation”, a very brief but crucial early phase during the first tiny fraction of a second of the Universe’s existence. As well as explaining many properties of the Universe as a whole, this initial expansion caused the ripples in the CMB that we see today.

Although this primordial epoch can’t be observed directly, the theory predicts a set of very subtle imprints on the CMB map. Previous experiments have not been able to confidently detect these subtle imprints, but the high resolution of Planck’s map confirms that the tiny variations in the density of the early Universe match those predicted by inflation.

(JPG, 811 Kb)
This illustration summarises the almost 14-billion-year long history of our Universe. It shows the main events that occurred between the initial phase of the cosmos, where its properties were almost uniform and punctuated only by tiny fluctuations, to the rich variety of cosmic structure that we observe today, from stars and planets to galaxies and galaxy clusters.
Credit: ESA – C. Carreau.

'The sizes of these tiny ripples hold the key to what happened in that first trillionth of a trillionth of a second. Planck has given us striking new evidence that indicates they were created during this incredibly fast expansion, just after the Big Bang’, explained Joanna Dunkley of the University of Oxford.



But because the precision of Planck’s map is so high, it also reveals some peculiar unexplained features that may well require new physics to be understood. Amongst the most surprising findings are that the fluctuations in the CMB over large scales do not match those predicted by the standard model. This anomaly adds to those observed by previous experiments, and confirmed by Planck, including an asymmetry in the average temperatures on opposite hemispheres of the sky, and a cold spot that extends over a patch of sky that is much larger than expected.

(JPG, 192 Kb)
One way to explain the anomalies is to propose that the Universe is in fact not the same in all directions on a larger scale than we can observe. In this scenario, the light rays from the CMB may have taken a more complicated route through the Universe than previously understood, 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,” says Professor Efstathiou.

Professor John Womersley, Chief Executive of the Science and Technology Facilities Council (STFC), said, “Planck has given us an amazing picture of the very earliest moments of the Universe. These results are the culmination of many years of work by UK scientists and engineers supported by STFC. This kind of project can sometimes seem expensive but the payoff in science and technology more than justifies the investment we've made.'   Download ESA's Planck toolkit. (PDF, 447 Kb)
"The maps we have obtained feature levels of resolution and sensitivity never achieved before, a milestone in modern cosmology", explains Andrea Zacchei, a researcher at the Osservatorio Astronomico of Trieste who, following Fabio Pasian, is now in charge of the entire data analysis of the LFI. "In a year's time the challenge will be even greater, as we will try to conclude the analysis of polarization data which may give us a few surprises regarding our comprehension of the Universe". The polarization is in fact the "direction" taken by the light, perpendicular to that in which it travels, that "remembers" very well the one that had been impressed on the Big Bang and it may therefore convey very important information.

"The observations carried out by Planck reveal with unprecedented exactness the imprint of the Big Bang on the fossil radiation. This the first time that man can look with such clearness at the origin of our Universe, in which we see the impact of forms of matter and energy still unknown today", adds Carlo Baccigalupi, a cosmologist at SISSA. "In order to comprehend Planck's data we still have to focus on the most mysterious part of the signal, in which we may look for space-time oscillations of cosmological dimension, and such information that may help identify the physical processes that occurred at the time of the Big Bang. A lot of work for scientists for many years to come". The task of Baccigalupi, alongside Luigi Danese, Francesca Perrotta and the SISSA group, is to extract the signal of the Big Bang and the main astrophysical emissions.

More in detail...

Planck is a satellite of the European Space Agency, designed to observe the Big Bang through the cosmic background radiation with unprecedented results.

Planned in the mid-90s, the satellite and the instruments it carries on board have been realized thanks to the huge effort of various European space agencies, while NASA created the cooling system.

Planck carries on board two instruments to observe the sky at several frequencies: the LFI (Low Frequency Instrument), under Italy's responsibility, which detects the radiation in the 30 to 70 GHz interval and the HFI (High Frequency Instrument), under France's responsibility, that observes it in the 100 to 857 GHz interval.

The analysis of the satellite-to-ground data has been carried out at two centers only in the world, Paris and Trieste. Trieste in particular, with SISSA, INAF-Osservatorio Astronomico and Università di Trieste, acts as the Data Processing Centre for the low-frequency instrument. In recent years about fifteen scientists from the three institutes have been collaborating zealously with continuous exchanges with the other Planck collaborators, that include the world's greatest experts in data analysis, computer science, cosmology and astrophysics, amounting to over 200 scientists and technicians.

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