Interview_Griffiths

INTER ACTIONS 1997

Richard Griffiths: The Medium Deep Survey
with the Hubble Space Telescope

When asked how many galaxies he has discovered through research, Richard Griffiths laughs and reports that he has stopped counting. But even after finding tens of thousands of new galaxies, he continues to be amazed at the wealth of data coming back from Hubble.

"The images of thousands of galaxies taken from the wide field camera are being used to unravel the origin and evolution of galaxies, from giants like the Milky Way, to the much more numerous dwarf galaxies," he says.

For Griffiths and others, the Hubble Space Telescope proves true to its promise to expand greatly our knowledge of the universe. The Medium Deep Survey, now in its sixth year, has led to more than 50 scientific publications for Griffiths and his research team, as well as numerous NASA announcements of their discoveries.

In the Medium Deep Survey, Hubble uses its wide field camera to search for unexpected objects in uncharted areas of the sky while another Hubble instrument conducts primary observations of different celestial targets. Pictures are taken in multiple wavelengths, including ultraviolet, visible and infrared.

These images, gathered in parallel, enhance our understanding of the origin and evolution of galaxies. They are among the wonderful visuals now being shown on television, published in magazines and written about in academic journals.

If the rewards of Hubble research are the discovery of the previously unknown and the unexpected, then Griffiths and his research team have been rewarded many times over by the data collected. The fabulous pictures and information sent back by Hubble's Medium Deep Survey provide hints about the building blocks of the universe.

For example, this serendipitous survey of the heavens uncovers remote and unusual galaxies never before resolved by optical telescopes. Some of the remote galaxies lack the familiar spiral and elliptical shapes characteristic of galaxies in the nearby universe. One cosmological model suggests that galaxies in this early universe interact dynamically and grow bigger by cannibalizing smaller regions in star formation. If that theory is true, says Griffiths, then the objects he and his research team found may be building blocks for today's larger galaxies.

In 1995, Griffiths and the international team of astronomers from the U.S. and Britain that are part of the Medium Deep Survey shed new light on one of the most puzzling, long standing mysteries of extra-galactic astronomy. The survey team reported that our universe is dominated by small, highly distorted galaxies with a strongly irregular appearance. Previously, astronomers believed that giant spiral galaxies like our own Milky Way dominated the vast volume of space.

Griffiths brought an entire research team, including Senior Research Scientist Kavan Ratnatunga, to Carnegie Mellon. Here, they'll be furthering their Hubble research and also looking at data collected from Griffiths' work in x-ray astronomy.

Griffiths began his research in the field of x-ray astronomy and he continues to work on the origin of x-ray background from space, using data in the form of deep images taken with earth-orbiting x-ray telescopes. With images from these x-ray satellites, he and other researchers use some of the world's largest optical telescopes to identify the kinds of galaxies that are the greatest producers of x-rays.

Hubble Space Telescope diagram.