Scientists See Light that May Be from First Objects in Universe(Forwarded)

Dewayne Washington
Goddard Space Flight Center Greenbelt, Md.
(301) 286-0040

M. Mitchell Waldrop
National Science Foundation, Arlington, Va.
(703) 292-7752

For Release: November 2, 2005

ssc2005-22

Scientists See Light that May Be from First Objects in Universe

Scientists using NASA's Spitzer Space Telescope say they have detected
light that may be from the earliest objects in the universe. If confirmed,
the observation provides a glimpse of an era more than 13 billion years
ago when, after the fading embers of the theorized Big Bang gave way to
millions of years of pervasive darkness, the universe came alive.

This light could be from the very first stars or perhaps from hot gas
falling into the first black holes. The science team, based at NASA
Goddard Space Flight Center in Greenbelt, Md., describes the observation
as seeing the glow of a distant city at night from an airplane. The light
is too distant and feeble to resolve individual objects.

"We think we are seeing the collective light from millions of the first
objects to form in the universe," said Dr. Alexander Kashlinsky, Science
Systems and Applications scientist and lead author on the Nature article
that appeared in the Nov. 3 issue. "The objects disappeared eons ago, yet
their light is still traveling across the universe."

Scientists theorize that space, time and matter originated 13.7 billion
years ago in a Big Bang. Another 200 million years would pass before the
era of first starlight. A 10-hour observation by Spitzer's infrared array
camera in the constellation Draco captured a diffuse glow of infrared
light, lower in energy than optical light and invisible to us. The Goddard
team says that this glow is likely from Population III stars, a
hypothesized class of stars thought to have formed before all others.
(Population I and II stars, named by order of their discovery, comprise
the familiar types of stars we see at night.)

Theorists say the first stars were likely over a hundred times more
massive than Earth's sun and extremely hot, bright, and short-lived, each
one burning for only a few million years. The ultraviolet light that
Population III stars emitted would be redshifted, or stretched to lower
energies, by the universe's expansion. That light should now be detectable
in the infrared.

"This deep observation was filled with familiar-looking stars and
galaxies," said Dr. John Mather, senior project scientist for JWST and a
co-author on the Nature article. "We removed everything we knew -- all the
stars and galaxies both near and far. We were left with a picture of part
of the sky with no stars or galaxies, but it still had this infrared glow
with giant blobs that we think could be the glow from the very first
stars."

This new Spitzer discovery agrees with observations from the NASA Cosmic
Background Explorer (COBE) satellite from the 1990s that suggested there
may be an infrared background that could not be attributed to known stars.
It also supports observations from the NASA Wilkinson Microwave Anisotropy
Probe from 2003, which estimated that stars first ignited 200 million to
400 million years after the Big Bang.

"This difficult measurement pushes the instrument to performance limits
that were not anticipated in its design," said team member Dr. S. Harvey
Moseley, instrument scientist for Spitzer. "We have worked very hard to
rule out other sources for the signal we observed."

The low noise and high resolution of Spitzer's infrared array camera
enabled the team to remove the fog of foreground galaxies, made of later
stellar populations, until the cumulative light from the first light
dominated the signal on large angular scales. The team, which also
includes Dr. Richard Arendt, Science Systems and Applications scientist,
noted that future missions, such as NASA's James Webb Space Telescope,
will find the first individual clumps of these stars or the individual
exploding stars that might have made the first black holes.

This analysis was partially funded through the National Science
Foundation. The Jet Propulsion Laboratory, Pasadena, Calif., manages the
Spitzer mission for NASA. Science operations are conducted at the Spitzer
Science Center at the California Institute of Technology in Pasadena. NASA
Goddard built Spitzer's infrared array camera which took the observations.
The instrument's principal investigator is Dr. Giovanni Fazio, Smithsonian
Astrophysical Observatory, Cambridge, Mass.

[NOTE: Images supporting this release are available at
http://www.spitzer.caltech.edu/Media.../visuals.shtml ]