WESTFORD, Mass. – An international collaboration of astronomers
including those at MIT’s Haystack Observatory has created an
Earth-sized virtual radio telescope capable of detecting
never-before-seen features of the universe.

The virtual device, which was created earlier this year by linking
signals from radio telescopes on several continents, can detect
features 3000 times smaller than the finest detail observed by the
Hubble Space Telescope.

“The resolution achieved by this telescope is the equivalent of sitting

in New York and being able to see the dimples on a golf ball in Los
Angeles,” said Sheperd Doeleman, research scientist at Haystack.

The telescope, which has successfully picked up radio signals from
galaxies over 3 billion light years away, will be used to address one
of the fundamental mysteries of modern astronomy — how so-called
“active” galaxies produce their incredible energetic output.

Normally, a galaxy gives off a predictable amount of energy, one
equaling the sum of the energies given off by each of its stars. Active
galaxies emit an amount that is far in excess of their stars’ combined
energies. This excess energy tends to be concentrated at the galaxy’s
core. Researchers believe these energetic cores are powered by
super-massive black holes, billions of times bigger than the Sun.
Erupting from some of these cores are powerful streams of high speed
particles that can extend millions of light years from the host galaxy.
But it is not clear how these high speed particle jets are launched
from the galactic cores.

The new telescope is specifically designed to make detailed images of
regions very close to where the jets originate.

“Locating the point at which these jets are turned on has been the Holy
Grail in this field,” Doeleman said. “Using the new telescope array, we
have detected two galactic cores which are allowing us to observe jet
behavior close to their nozzles.”

A key to the power of the new telescope lies in its angular resolution
— its ability to clearly separate two closely spaced objects in the
sky. This ability can be improved by either increasing the size of a
telescope or by observing at higher frequencies. To increase telescope
size, the scientists programmed telescopes on several continents to
record radio emissions from the same object at the same time, using a
technique called Very Long Baseline Interferometry (VLBI). Signals from
each telescope were time stamped with extremely accurate atomic clocks,
recorded on magnetic tapes, then combined in a correlator, a special
purpose super-computer. This technique forms a virtual radio telescope
whose size can be as large as the diameter of the Earth.

To further increase resolution, the virtual telescope was programmed to
observe at extremely high radio frequencies (129GHz and 147GHz). The
angular resolution achieved by the telescope in its record-breaking
test was 50 micro arc seconds, approximately one hundred millionth of a
degree.

The array of telescopes used in these observations reflects the
international nature of the scientific collaboration. Telescopes in the
United States (Arizona), Spain, Finland and Chile participated in the
observations. Two telescopes in Arizona and one in Spain provided key
long distance detections that were especially critical to the project.

“We are delighted that the two Arizona sites were able to anchor this
collaborative effort in the US,” said Lucy Ziurys, director of the
Arizona Radio Observatory in Tucson. “The Arizona telescopes will be
crucial to future high frequency VLBI experiments and we very much look
forward to continuing this exciting new field of research.”

Scientists will be using this technique to target the core of our own
Milky Way Galaxy where a suspected black hole three million times more
massive than the Sun may be lurking. If this central radio source can
be imaged using high frequency VLBI, structures very close to the black
hole could become visible.

“It might even be possible to observe the effects of General Relativity
like the distortion of space-time in the direct neighborhood of a
super-massive black hole within the next 10-20 years,” said Thomas
Krichbaum of the Max Planck Institute for Radio Astronomy in Bonn,
Germany.

Reports of the experiment were presented by Doeleman and Krichbaum at
the annual European VLBI Network conference in Bonn, Germany.
Scientists and engineers from the following institutes made this
experiment possible: The MIT-Haystack Observatory in Westford, MA, USA;
the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn/Germany;
the Steward Observatory, in Tucson, AZ, USA, which operates the Arizona
Radio Observatory; IRAM, in Granada, Spain and Grenoble, France; the
Metsaehovi Radio Observatory in Finland; the ESO-Swedish operated
SEST-telescope; and the National Radio Astronomy Observatory in the
USA. The US effort in this project is supported by the National Science
Foundation and the Tucson-based Research Corporation.