Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Pushing back the frontiers of the universe to the era of the first stars

10.03.2003


UK astronomers Elizabeth Stanway, Andrew Bunker and Richard McMahon at the Institute of Astronomy, University of Cambridge, England, have used three of the most powerful telescopes in existence to identify some of the farthest galaxies yet seen. But at the same time, they have encountered a cosmic conundrum: it looks as if there were fewer galaxies forming stars at this early stage in the history of the Universe than in the more recent past. Their results, which will be published in the Monthly Notices of the Royal Astronomical Society, show for the first time, that astronomers may be probing back to the era when the first stars and galaxies were forming.



Stanway, Bunker and McMahon used the unique power of the Hubble Space Telescope and analysed publicly-available images taken in the direction of the southern hemisphere constellation of Fornax (the Oven) with the new Advanced Camera for Surveys as part of the ’Great Observatory Origins Deep Survey’ (GOODS) project. They identified half a dozen objects likely to be galaxies 95 per cent of the way across the observable Universe. The redshifts of these galaxies are about 6 and they are so far away that radiation from them has taken about 13 billion years to reach us. They existed when the Universe was less than a billion years old and seven billion years before the Earth and Sun formed. Intervening gas clouds absorbed visible light from them long before it reached Earth but their infrared light can be detected - and it is their infrared ’colours’ which lead the researchers to believe that they lie at such immense distances.

They also used infrared images taken with one of the 8-metre telescopes forming the Very Large Telescope (VLT) at the European Southern Observatory (ESO) in Chile to study these galaxies. "The ESO pictures allowed us to distinguish very distant galaxies at the edge of the observable Universe from objects nearby," said graduate student Elizabeth Stanway, who has identified the galaxies as part of her research for a doctorate in astrophysics at Cambridge.


Having drawn up a list of objects that could be remote galaxies, the astronomers then turned to one of two Keck telescopes, which are the largest in the world and are at the top of the 14000ft mountain of Mauna Kea in Hawaii. Working with California astronomers Professor Richard Ellis (Caltech) and Dr Patrick McCarthy (Carnegie Observatories) they took a spectrum of one of them. They saw the signature of hydrogen gas glowing as it is illuminated by hot, newly-born stars, and measured the redshift to be 5.78. "This galaxy is in the process of giving birth to stars - each year it converts a mass of gas more than 30 times that of our Sun into new stars", according to research astronomer Dr. Andrew Bunker. These additional results have recently been submitted to the Monthly Notices of the Royal Astronomical Society.

"Using the Keck, was very important as it showed that this population of objects discovered by the Hubble Space Telescope really is incredibly distant", said Andrew Bunker, who was part of the team which did the observing in Hawaii. "The galaxy we have proved to be very distant is only 1000 light years across. This is very small compared to our own galaxy, the Milky Way, which is 100 times larger" added Elizabeth Stanway.

But the Cambridge team have also found a cosmic puzzle: on the basis of their sample, they can calculate how may galaxies there are involved in the rapid formation of stars in the very distant universe (redshift 6). They have compared the answer with previous work looking at nearer galaxies, with redshifts around 4. It seems that there are fewer of these galaxies early in the history of the Universe, compared to more recent times.

Theoretical predictions for the star formation history of the universe are highly uncertain, which is why this observational work is essential. "It could be that we are seeing some of the first galaxies to be born", said Richard McMahon, "The light from these first stars to ignite could have ended the Dark Age of the Universe as the galaxies ’turn on’, and might have caused the gas between the galaxies to be blasted by starlight - the ’reionization’ which has recently been detected in the cosmic microwave background by the WMAP satellite". The results of the Cambridge group combined with the recent results from WMAP satellite complement each other and show that the Dark Age ended sometime between 200 and 1000 million years after the Big Bang with the formation of the first stars.

This team of astronomers are currently building a new instrument in Cambridge called ’DAZLE’, which will probe even earlier in the history of the Universe and shed new light on the ’Dark Ages’.

Elizabeth Stanway | alfa
Further information:
http://www.ast.cam.ac.uk/~bunker/internal/CambridgeGOODS/

More articles from Physics and Astronomy:

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Quantum thermometer or optical refrigerator?
23.06.2017 | National Institute of Standards and Technology (NIST)

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>