RAS PN09/35 (NAM22): EMBARGOED UNTIL 00:01 BST, WEDNESDAY 22ND APRIL 2009
Dr. Robert Massey
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HUBBLE SURVEY REVEALS THE FORMATION OF THE FIRST MASSIVE GALAXIES
First results from the GOODS NICMOS survey, the largest Hubble Space Telescope programme ever led from outside of the United States, reveal how the most massive galaxies in the early Universe assembled to form the most massive objects in the Universe today. Dr Chris Conselice from the University of Nottingham will present the results at the European Week of Astronomy and Space Science at the University of Hertfordshire on Wednesday 22nd April.
The observations are part of the Great Observatories Origins Deep Survey (GOODS), a campaign that is using NASA’s Spitzer, Hubble and Chandra space telescopes together with ESA’s XMM Newton X-ray observatory to study the most distant Universe. A team of scientists from six countries used the NICMOS near infrared camera on the Hubble Space Telescope to carry out the deepest ever survey of its type at near infrared wavelengths. Early results show that the most massive galaxies, which have masses roughly 10 times larger than the Milky Way, were involved in significant levels of galaxy mergers and interactions when the Universe was just 2-3 billion years old.
“As almost all of these massive galaxies are invisible in the optical wavelengths, this is the first time that most of them have been observed,” said Dr Conselice, who is the Principal Investigator for the survey. “To assess the level of interaction and mergers between the massive galaxies, we searched for galaxies in pairs, close enough to each other to merge within a given time-scale. While the galaxies are very massive and at first sight may appear fully formed, the results show that they have experienced an average of two significant merging events during their life-times.”
The GOODS NICMOS results show that these galaxies did not form in a simple collapse in the early universe, but that their formation is more gradual over the course of the Universe's evolution, taking about 5 billion years.
Dr Conselice said, “The findings support a basic prediction of the dominant model of the Universe, known as Cold Dark Matter, so they reveal not only how the most massive galaxies are forming, but also that the model that’s been developed to describe the Universe, based on the distribution of galaxies that we’ve observed overall, applies in its basic form to galaxy formation.”
The preliminary results are based on a paper led by PhD student Asa Bluck at the University of Nottingham.
Images can be found at:
NOTES FOR EDITORS
THE EUROPEAN WEEK OF ASTRONOMY AND SPACE SCIENCE
More than 1000 astronomers and space scientists will gather at the University of Hertfordshire for the European Week of Astronomy and Space Science (EWASS), incorporating the 2009 Royal Astronomical Society National Astronomy Meeting (RAS NAM 2009) and the European Astronomical Society Joint Meeting (JENAM 2009). The meeting runs from 20th to 23rd April 2009.
EWASS is held in conjunction with the UK Solar Physics (UKSP) and Magnetosphere Ionosphere and Solar-Terrestrial Physics (MIST) meetings. The conference includes scientific sessions organised by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO) and the European Space Agency (ESA).
EWASS is principally sponsored by the Royal Astronomical Society (RAS), the Science and Technology Facilities Council (STFC) and the University of Hertfordshire, Hatfield.
THE ROYAL ASTRONOMICAL SOCIETY
The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organizes scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.
Christopher J. Conselice
Associate Professor and Reader of Astrophysics
School of Physics and Astronomy
Senior Tutor, Cripps Hall
University of Nottingham
Nottingham, NG7 2RD
Tel: 44 0115 951 5137