Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers find the most distant known galaxies

11.07.2007
Using natural ‘gravitational lenses’, an international team of astronomers claim to have found a hint of a population of the most distant galaxies yet seen - the light we see from them today left more than 13 thousand million years ago, when the Universe was just 500 million years old.

Team leader Professor Richard Ellis, Steele Professor of Astronomy at Caltech, will present images of these faint and distant objects in his talk on Wednesday 11 July at the ‘From IRAS to Herschel and Planck’ conference at the Geological Society in London. The meeting is being held to celebrate the 65th birthday of Royal Astronomical Society President Professor Michael Rowan-Robinson.

When light from very distant bodies passes through the gravitational field of much nearer massive objects, it bends in an effect known as ‘gravitational lensing’. In a pioneering technique, the Caltech-led group used massive clusters of galaxies – the best example of natural gravitational lenses - in a series of campaigns to locate progressively more distant systems that would not be detected in normal surveys. The team found the galaxies using one of the most powerful telescopes in the world, the Keck II, which has a 10 m diameter mirror and is sited on Mauna Kea, Hawaii.

Richard Ellis explains, "Gravitational lensing is the magnification of distant sources by foreground structures. By looking through carefully-selected clusters, we have located 6 star forming galaxies seen at unprecedented distances, corresponding to a time when the Universe was only 500 million years old, or less than 4% of its present age."

When the Universe was 300,000 years old it is thought to have entered a period when no stars were shining. Cosmologists refer to this phase of cosmic history as the `Dark Ages'. Pinpointing the moment of `cosmic dawn' when the first stars and galaxies began to shine and the dark ages ended is a major observational quest and provides the motivation for building future powerful telescopes such as the European Southern Observatory’s Extremely Large Telescope, the US/Canadian Thirty Meter Telescope and the space-borne James Webb Telescope.

The new survey represents 3 years' painstaking observations summarised in the thesis of graduate student, Mr Dan Stark. "Using Keck II, we have detected 6 faint star-forming galaxies whose signal has been boosted about 20 times by the magnifying effect of a foreground cluster. That we should find so many distant galaxies in our small survey area suggests they are very numerous indeed. We estimate the combined radiation output of this population could be sufficient to break apart (ionize) the hydrogen atoms in space at that time, thereby ending the Dark Ages" said Mr Stark.

Proving definitively that each of the 6 objects is unambiguously at these enormous distances (and hence being viewed at such early times) is hard, even with the most powerful facilities. "As with all work at the frontiers, skeptics may wish to see further proof that the objects we are detecting with Keck are really so distant", confessed Ellis. However, in addition to numerous checks the team has made following their initial discovery a year ago, Ellis and Stark point to supporting evidence from galaxies containing old stars that are seen when the Universe was just a bit older.

"We can infer the Universe had a lot of star formation at these early times from Spitzer Space Telescope measurements of larger galaxies seen when the Universe was about 300-500 million years older", explains Mr Stark. "These galaxies show the tell-tale sign of old stars (and were described in earlier work by University of Exeter scientist Dr Andrew Bunker). To produce these old stars requires significant earlier activity, most likely in the fainter star-forming galaxies we have now seen."

Also associated with the programme is Caltech postdoctoral scholar, Dr Johan Richard, who is leading a similar, but independent, survey of magnified galaxies detected with the Hubble and Spitzer Space Telescopes. Although that work is not yet complete, preliminary findings support the conclusions of the Keck II survey. European collaborators include Professor Jean-Paul Kneib of the Laboratory of Astrophysics at Marseilles, and Dr Graham Smith at the University of Birmingham.

Robert Massey | alfa
Further information:
http://www.ras.org.uk
http://www.astro.caltech.edu/~johan/cosmic_dawn/

More articles from Physics and Astronomy:

nachricht NASA detects solar flare pulses at Sun and Earth
17.11.2017 | NASA/Goddard Space Flight Center

nachricht Pluto's hydrocarbon haze keeps dwarf planet colder than expected
16.11.2017 | University of California - Santa Cruz

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: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>