The BOSS instrument, at the Apache
Point Observatory in New Mexico,
features 1,000 optical fibers that can
detect light signals from the dimmest
and most distant galaxies. For DESI, the
engineers used five times as many fibers.
BOSS researchers have to use metal
plates with carefully drilled holes to
direct the optical fibers toward their
targets. For every portion of the sky they
want to image, the engineers need to
create new plates and mount them
onto the telescope. In the case of DESI,
the robots will do all the hard work,
considerably increasing the speed of
the scanning, the researchers said.
"There are 5,000 individual robots, and
each one drives one optical fiber,"
Silber told Live Science. "The optical
fiber is then routed about 50 meters
[about 164 feet] down the telescope to
a separate room where these very
large and sensitive spectrograph
instruments are installed."
By measuring how the wavelength of
light coming from distant galaxies (or
any celestial object) changes, the
researchers will be able to figure out
how far away they are and how fast
the galaxies are moving away. When
an object is moving away from us, its
light shifts toward the red part of the
light spectrum (a longer wavelength),
and that's why it's called redshift.
The scale and complexity of the map
will help the scientists understand how
dark
energy
and
gravity
have
competed throughout the evolution of
the universe. Dark energy is the yet
unproven force that competes with
gravity and causes the accelerating
expansion of the universe. It is
estimated that the dark energy makes
up to 68 percent of the total energy
present in the universe.
The sensitivity of the instrument will
allow the astronomers to see galaxies
so distant that their light travels to Earth
many billions of years. The researchers
said the instrument, by looking at how
long it takes the light to reach it, would
allow them to see back as far as 11
billion years ago. [Our Expanding
Universe: Age, History and Other Facts]
"One of the primary ways that we learn
about the unseen universe is by its
subtle effects on the clustering of
galaxies," said DESI Collaboration co-
spokesperson Daniel Eisenstein of
Harvard University. "The new maps from
DESI will provide an exquisite new level
of sensitivity in our study of cosmology."
During its planned five years of
operations, DESI will measure velocities
of some 30 million galaxies and quasars
—
super
massive
black
holes
surrounded by a disk of orbiting
material, according to Brenna Flaugher,
a DESI project scientist who leads the
Astrophysics Department at the Fermi
National Accelerator Laboratory.
"Instead of one at a time, we can
measure the velocities of 5,000 galaxies
at a time," she said.
The instrument, a collaboration among
71 research institutions, will capture
about 10 times more data than its
predecessor, BOSS.
"This project is all about generating
huge quantities of data," said DESI
Director
Michael
Levi
of
the
Department of Energy's Lawrence
Berkeley National Laboratory (Berkeley
Lab), which is leading the project. The
researchers will use the data in
computer simulations of universes.
Silber and his team have already
produced 3,000 positioning robots and
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