The discovery was made by an international team of astronomers led by Raphael Gavazzi and Tommaso Treu of the University of Californi, Santa
Barbara. Treu says the odds of seeing such a special alignment are so
small that they “hit the jackpot” with this discovery. “When I first
saw it I said ‘wow, this is insane!’ I could not believe it!”
this sight is more than just an incredible novelty. It’s also a very
rare phenomenon that can offer insights into dark matter, dark energy,
the nature of distant galaxies, and the curvature of the Universe
itself. The discovery is part of the ongoing Sloan Lens Advanced Camera
for Surveys (SLACS) program.
phenomenon, called gravitational lensing, occurs when a massive galaxy
in the foreground bends the light rays from a distant galaxy behind it,
in much the same way as a magnifying glass would. When both galaxies
are perfectly lined up, the light forms a circle, called an “Einstein
ring”, around the foreground galaxy. If another more distant galaxy
lies precisely on the same sightline, a second, larger ring will appear.“Such
stunning cosmic coincidences reveal so much about nature. Dark matter
is not hidden to lensing,” added Leonidas Moustakas of the Jet
Propulsion Laboratory in Pasaden, California, USA. “The elegance of this lens is trumped only by the secrets of nature that it reveals.”The
dark matter distribution in the foreground galaxies that is warping
space to create the Einstein's telescope, the gravitational lens, can
be accurately mapped. In addition, the geometry of the two Einstein
rings allowed the team to measure the mass of the middle galaxy
precisely to be a value of 1 billion solar masses. The team reports
that this is the first measurement of the mass of a dwarf galaxy at
sample of several dozen double rings such as this one would offer a
purely independent measure of the curvature of space by gravity. This
would help in determining what the majority of the Universe is made of,
and the properties of dark energy.
Original observations made in 1970 revealed that gravitational motions
of gas clouds in the Andromeda galaxy were occurring at speeds far
greater than the entire observed mass of that galaxy could account for.
Similar problems detected in the 1930's involving motions of entire
galaxies had long been disregarded. Later observations confirmed that
so-called "ordinary matter" is insufficient to account for observed
gravitational effects in the cosmos. Thus the universe must contain
huge amounts of "dark matter," that we cannot observe and the
composition of which we do not know.
1998 reports of observations of distant supernovae revealed that the
expansion of the universe was not slowing, as would be expected from
long-term effects of gravity, but was instead accelerating. Something
was overcoming the gravitational power of all of the matter in the
universe. The acceleration, moreover, has not been present from the Big
Bang on. For billions of years the speed of expansion slowed. Then,
about 5 billion years ago, acceleration began. Obviously energy--a lot
of it--- was required to explain these phenomena. This is "dark
energy." We cannot detect it and currently know almost nothing about
scientists believe that 5% of the universe consists of "ordinary"
[observable] matter, 23% of "dark" matter and 72% of "dark energy."