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National Radio Astronomy Observatory
P.O. Box O
Socorro, NM 87801
http://www.nrao.edu

Contact:
Dave Finley
Public Information Officer, Socorro, NM
(505) 835-7302, dfinley{at}nrao.edu

April 3, 2003

Giant Cosmic Lens Reveals Secrets of Distant Galaxy

Part 2 of 2

"Our guess paid off handsomely. Finding that Einstein
Ring with the VLA gave us the tool we needed to see
what was going on inside that very distant galaxy,"
said Carilli. "There are fewer than 100 gravitational
lenses known so far, and we were extremely lucky to
find one that allowed us to help resolve the specific
scientific question we were studying."

Gravitational lenses were predicted, based on Albert
Einstein's General Theory of Relativity, in 1919.
Einstein himself showed in 1936 that a perfectly-
aligned gravitational lens would produce a circular
image, but felt that the chances of actually
observing such an object were nearly zero. The first
gravitational lens was discovered in 1979, and the
first Einstein Ring was discovered by researchers
using the VLA in 1987. PSS J2322+1944 is the first
Einstein Ring detected through the signature emission
of a molecule and the most distant yet found.

PSS J2322+1944 may be able to make another contribution
to science. Astronomers believe that gravitational
lenses may serve as a tool for precisely measuring great
distances in the Universe. If a distant quasar varies
in brightness over time, the multiple images formed by
a gravitational lens would show that variation at
different times. By monitoring such time differences
and using a mathematical model of the specific
gravitational lens, the distance to the quasar can be
measured.

"This quasar, if it shows brightness variations in the
future, may be such a 'Golden Lens,' long sought to
refine our measurement of very great distances," said
Lewis.

In addition to Carilli, Lewis, Djorgovski, Cox and Omont,
the research team includes Ashish Mahabal of Caltech and
Frank Bertoldi of the Max-Planck Institute for Radio
Astronomy in Bonn, Germany.

The National Radio Astronomy Observatory is a facility
of the National Science Foundation, operated under
cooperative agreement by Associated Universities, Inc.

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