First results from the GOODS NICMOS survey, the largest Hubble Space
Telescope program 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.