Pressmeddelande

Looking Deep with Infrared Eyes

First data release from UKIRT Infrared Deep Sky Survey [1]

21 juli 2006

Today, British astronomers are releasing the first data from the largest and most sensitive survey of the heavens in infrared light to the ESO user community. The UKIRT Infrared Deep Sky Survey (UKIDSS) has completed the first of seven years of data collection, studying objects that are too faint to see at visible wavelengths, such as very distant or very cool objects. New data on young galaxies is already challenging current thinking on galaxy formation, revealing galaxies that are massive at a much earlier stage of development than expected. These first science results already show how powerful the full survey will be at finding rare objects that hold vital clues to how stars and galaxies in our Universe formed.

UKIDSS will make an atlas of large areas of the sky in the infrared. The data become available to the entire ESO user community immediately after they are entered into the archive [2]. Release to the world follows 18 months after each release to ESO.

"Astronomers across Europe will jump on these exciting new data. We are moving into new territory - our survey is both wide and deep, so we are mapping huge volumes of space. That's how we will locate rare objects - the very nearest and smallest stars, and young galaxies at the edge of the universe," said Andy Lawrence from the University of Edinburgh, UKIDSS Principal Investigator.

The UKIDSS data are collected by the United Kingdom Infrared Telescope [3] situated near the summit of Mauna Kea in Hawaii using the Wide Field Camera (WFCAM) built by the United Kingdom Astronomy Technology Centre (UKATC) in Edinburgh. WFCAM is the most powerful infrared imager in the world, generating enormous amounts of data - 150 gigabytes per night (equivalent to more than 200 CDs) - and approximately 10.5 Terabytes in total so far (or 15,000 CDs). Mark Casali, now at ESO, was the Project Scientist in charge of the WFCAM instrument construction at the UKATC.

"WFCAM was a bold technological undertaking," said Mark Casali. "Nothing quite like it has ever been built before. The fact that it is working reliably and reaching its theoretical sensitivity is a testament to the hard work and skill of the engineering team at the UKATC."

Faint Red Galaxy in the UKIDSS Ultra-Deep Survey

A small amount of data was released in January 2006 and already teams led by Omar Almaini at the University of Nottingham and Nigel Hambly of the Institute for Astronomy at the University of Edinburgh are beginning to reveal some of the secrets of star and galaxy formation.

Omar Almaini, Ross McLure and the Ultra Deep Survey team have been looking at distant galaxies by surveying the same region of sky night after night to see deeper and to find these very faint objects. This survey will be one hundred times larger than any similar survey attempted to date and will cover an area four times the size of the full Moon. So far several hundred thousand galaxies have been detected and among the early discoveries, nine remarkable galaxies have been found that appear to be 12 billion light years away. As it has taken 12 billion years for the light to travel from these galaxies to Earth, we are seeing them as they were when they were very young - only a billion years after the Big Bang. The newly discovered galaxies are unusual as they appear to be very massive for their age. This challenges thinking on how galaxies form, since it was thought that large galaxies form gradually over billions of years as smaller components merge together.

"We're surveying an enormous volume of the distant Universe, which allows us to discover rare massive galaxies that were previously almost impossible to find. Understanding how these galaxies form is one of the Holy Grails of modern astronomy, and now we can trace them back to the edge of the known Universe" said Omar Almaini.

Nigel Hambly and Nicolas Lodieu have been using the UKIDSS data to discover more about very cold objects in our Galaxy called brown dwarfs. Brown dwarfs are formed in the same way as stars but have typically less than 8% of the mass of the Sun (or approximately 80 times the mass of Jupiter). This is not large enough for core nuclear reactions to occur, and so brown dwarfs do not shine like normal stars. Brown dwarfs give off less than one ten thousandth of the radiation of a star like our Sun. This relatively tiny amount of heat can be detected by WFCAM and the UKIDSS survey hopes to find out how many of these "failed stars" there are in our Galaxy.

Nigel Hambly, of the UKIDSS Galactic Clusters Survey said: "With UKIDSS, we will find many thousands of brown dwarfs in many different star formation environments within our own Galaxy; furthermore we expect to find even cooler and much dimmer objects than are currently known. This will tell us how significant a role the brown dwarfs have in the overall scheme of Galactic structure and evolution."

Noter

[1]: This is a joint PPARC/ESO Press release. The PPARC version is available at http://www.pparc.ac.uk/Nw/ukidss2107.asp. ESO access to the data from the Wide-Field Camera on the UK Infrared Telescope is part of the arrangements agreed for the UK accession to ESO.

[2]: Access to the Data Release 1 is through the WFCAM Science Archive at http://surveys.roe.ac.uk/wsa.

[3]: UKIRT is the world's largest telescope dedicated solely to infrared astronomy. The 3.8-metre telescope is sited near the summit of Mauna Kea, Hawaii, at an altitude of 4194 metres above sea level. It is operated by the Joint Astronomy Centre in Hilo, Hawaii, on behalf of the UK Particle Physics and Astronomy Research Council (PPARC).

Kontakter

Mark Casali
ESO
Garching, Germany
Tel: +49 89 3200 6661
E-post: mcasali@eso.org

Andy Lawrence
Institute for Astronomy, University of Edinburgh
Edinburgh, UK
Tel: +44 131-668-8346
E-post: al@roe.ac.uk

Steve Warren
Imperial College
London, UK
Tel: +44 207-5947554
E-post: s.j.warren@imperial.ac.uk

Nigel Hambly
UKIDSS Galactic Clusters Survey
Edinburgh, UK
Tel: +44 131-668-8234
E-post: nch@roe.ac.uk

Omar Almaini
UKIDSS Ultra-Deep Survey
Nottingham, UK
Tel: +44 115-8467901
E-post: omar.almaini@nottingham.ac.uk

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