Andrew Yee
March 8th 06, 06:09 PM
Office of Public Information
Eberly College of Science
Penn State University
University Park, Pennsylvania
SCIENCE CONTACTS:
David Burrows
Lead scientist for Swift's X-ray telescope
and
Senior scientist and professor of astronomy and astrophysics, Penn State
814 865-7707
Neil Gehrels
Swift principal investigator, NASA's Goddard Space Flight Center
301-286-6546
P.I.O. CONTACTS:
Barbara K. Kennedy, Penn State PIO
814-863-4682
Lynn Cominsky, Swift PIO
707-664-2655
EMBARGOED: Not for publication in any medium until 1:00 p.m. U.S. Eastern
time (1800 London time) on 8 March 2006.
Scientists Piece Together the Most Distant Cosmic Explosion
It came from the edge of the visible universe, the most distant explosion
ever detected.
In this week's issue of Nature, scientists at Penn State University and
their U.S. and European colleagues discuss how this explosion, detected on
4 September 2005, was the result of a massive star collapsing into a black
hole.
The explosion, called a gamma-ray burst, comes from an era soon after
stars and galaxies first formed, about 500 million to 1 billion years
after the Big Bang. The universe is now 13.7 billion years old, so the
September burst serves as a probe to study the conditions of the early
universe.
"This was a massive star that lived fast and died young," said David
Burrows, senior scientist and professor of astronomy and astrophysics at
Penn State, a co-author on one of the three reports about this explosion
published this week in Nature. "This star was probably quite different
from the kind we see today, the type that only could have existed in the
early universe."
The burst, named GRB 050904 after the date it was spotted, was detected by
NASA's Swift satellite, which is operated by Penn State. Swift provided
the burst coordinates so that other satellites and ground-based telescopes
could observe the burst. Bursts typically last only 10 seconds, but the
afterglow will linger for a few days.
GRB 050904 originated 13 billion light years from Earth, which means it
occurred 13 billion years ago, for it took that long for the light to
reach us. Scientists have detected only a few objects more than 12 billion
light years away, so the burst is extremely important in understanding the
universe beyond the reach of the largest telescopes.
"Because the burst was brighter than a billion suns, many telescopes could
study it even from such a huge distance," said Burrows, whose analysis
focuses mainly on Swift data from its three telescopes, covering a range
of gamma-rays, X-rays, and ultraviolet/optical wavelengths, respectively.
Burrows is the lead scientist for Swift's X-ray telescope.
The Swift team found several unique features in GRB 050904. The burst was
long -- lasting about 500 seconds -- and the tail end of the burst
exhibited multiple flares. These characteristics imply that the newly
created black hole didn't form instantly, as some scientists have thought,
but rather it was a longer, chaotic event.
Closer gamma-ray bursts do not have as much flaring, implying that the
earliest black holes may have formed differently from ones in the modern
era, Burrows said. The difference could be because the first stars were
more massive than modern stars. Or, it could be the result of the
environment of the early universe when the first stars began to convert
hydrogen and helium (created in the Big Bang) into heavier elements.
GRB 050904, in fact, shows hints of newly minted heavier elements,
according to data from ground-based telescopes. This discovery is the
subject of a second Nature article by a Japanese group led by Nobuyuki
Kawai at the Tokyo Institute of Technology.
GRB 050904 also exhibited time dilation, a result of the vast expansion of
the universe during the 13 billion years that it took the light to reach
us on Earth. This dilation results in the light appearing much redder than
when it was emitted in the burst, and it also alters our perception of
time as compared to the burst's internal clock.
These factors worked in the scientists' favor. The Penn State team turned
Swift's instruments onto the burst about 2 minutes after the event began.
The burst, however, was evolving as if it were in slow motion and was only
about 23 seconds into the bursting. So scientists could see the burst at a
very early stage.
Only one other object -- a quasar -- has been discovered at a greater
distance. Yet, whereas quasars are supermassive black holes containing the
mass of billions of stars, this burst comes from a single star. The
detection of GRB 050904 confirms that massive stars mingled with the
oldest quasars. It also confirms that even more explosions of distant
stars -- perhaps from the first stars, theorists say -- can be studied
through a combination of observations with Swift and other world-class
telescopes.
"We designed Swift to look for faint bursts coming from the edge of the
universe," said Neil Gehrels of NASA Goddard Space Flight Center in
Greenbelt, Maryland, Swift's principal investigator. "Now we've got one
and it's fascinating. For the first, time we can learn about individual
stars from near the beginning of time. There are surely many more out
there."
Swift was launched in November 2004 and was fully operational by January
2005. Swift carries three main instruments: the Burst Alert Telescope, the
X-ray Telescope, and the Ultraviolet/Optical Telescope. Swift's gamma-ray
detector, the Burst Alert Telescope, provides the rapid initial location,
was built primarily by the NASA Goddard Space Flight Center in Greenbelt
and Los Alamos National Laboratory, and was constructed at GSFC. Swift's
X-Ray Telescope and UV/Optical Telescope were developed and built by
international teams led by Penn State and drew heavily on each
institution's experience with previous space missions. The X-ray Telescope
resulted from Penn State's collaboration with the University of Leicester
in England and the Brera Astronomical Observatory in Italy. The
Ultraviolet/Optical Telescope resulted from Penn State's collaboration
with the Mullard Space Science Laboratory of the University
College-London. These three telescopes give Swift the ability to do almost
immediate follow-up observations of most gamma-ray bursts because Swift
can rotate so quickly to point toward the source of the gamma-ray signal.
[NOTE: Images and movies supporting this release are available at
http://www.science.psu.edu/alert/Burrows3-2006.htm ]
Eberly College of Science
Penn State University
University Park, Pennsylvania
SCIENCE CONTACTS:
David Burrows
Lead scientist for Swift's X-ray telescope
and
Senior scientist and professor of astronomy and astrophysics, Penn State
814 865-7707
Neil Gehrels
Swift principal investigator, NASA's Goddard Space Flight Center
301-286-6546
P.I.O. CONTACTS:
Barbara K. Kennedy, Penn State PIO
814-863-4682
Lynn Cominsky, Swift PIO
707-664-2655
EMBARGOED: Not for publication in any medium until 1:00 p.m. U.S. Eastern
time (1800 London time) on 8 March 2006.
Scientists Piece Together the Most Distant Cosmic Explosion
It came from the edge of the visible universe, the most distant explosion
ever detected.
In this week's issue of Nature, scientists at Penn State University and
their U.S. and European colleagues discuss how this explosion, detected on
4 September 2005, was the result of a massive star collapsing into a black
hole.
The explosion, called a gamma-ray burst, comes from an era soon after
stars and galaxies first formed, about 500 million to 1 billion years
after the Big Bang. The universe is now 13.7 billion years old, so the
September burst serves as a probe to study the conditions of the early
universe.
"This was a massive star that lived fast and died young," said David
Burrows, senior scientist and professor of astronomy and astrophysics at
Penn State, a co-author on one of the three reports about this explosion
published this week in Nature. "This star was probably quite different
from the kind we see today, the type that only could have existed in the
early universe."
The burst, named GRB 050904 after the date it was spotted, was detected by
NASA's Swift satellite, which is operated by Penn State. Swift provided
the burst coordinates so that other satellites and ground-based telescopes
could observe the burst. Bursts typically last only 10 seconds, but the
afterglow will linger for a few days.
GRB 050904 originated 13 billion light years from Earth, which means it
occurred 13 billion years ago, for it took that long for the light to
reach us. Scientists have detected only a few objects more than 12 billion
light years away, so the burst is extremely important in understanding the
universe beyond the reach of the largest telescopes.
"Because the burst was brighter than a billion suns, many telescopes could
study it even from such a huge distance," said Burrows, whose analysis
focuses mainly on Swift data from its three telescopes, covering a range
of gamma-rays, X-rays, and ultraviolet/optical wavelengths, respectively.
Burrows is the lead scientist for Swift's X-ray telescope.
The Swift team found several unique features in GRB 050904. The burst was
long -- lasting about 500 seconds -- and the tail end of the burst
exhibited multiple flares. These characteristics imply that the newly
created black hole didn't form instantly, as some scientists have thought,
but rather it was a longer, chaotic event.
Closer gamma-ray bursts do not have as much flaring, implying that the
earliest black holes may have formed differently from ones in the modern
era, Burrows said. The difference could be because the first stars were
more massive than modern stars. Or, it could be the result of the
environment of the early universe when the first stars began to convert
hydrogen and helium (created in the Big Bang) into heavier elements.
GRB 050904, in fact, shows hints of newly minted heavier elements,
according to data from ground-based telescopes. This discovery is the
subject of a second Nature article by a Japanese group led by Nobuyuki
Kawai at the Tokyo Institute of Technology.
GRB 050904 also exhibited time dilation, a result of the vast expansion of
the universe during the 13 billion years that it took the light to reach
us on Earth. This dilation results in the light appearing much redder than
when it was emitted in the burst, and it also alters our perception of
time as compared to the burst's internal clock.
These factors worked in the scientists' favor. The Penn State team turned
Swift's instruments onto the burst about 2 minutes after the event began.
The burst, however, was evolving as if it were in slow motion and was only
about 23 seconds into the bursting. So scientists could see the burst at a
very early stage.
Only one other object -- a quasar -- has been discovered at a greater
distance. Yet, whereas quasars are supermassive black holes containing the
mass of billions of stars, this burst comes from a single star. The
detection of GRB 050904 confirms that massive stars mingled with the
oldest quasars. It also confirms that even more explosions of distant
stars -- perhaps from the first stars, theorists say -- can be studied
through a combination of observations with Swift and other world-class
telescopes.
"We designed Swift to look for faint bursts coming from the edge of the
universe," said Neil Gehrels of NASA Goddard Space Flight Center in
Greenbelt, Maryland, Swift's principal investigator. "Now we've got one
and it's fascinating. For the first, time we can learn about individual
stars from near the beginning of time. There are surely many more out
there."
Swift was launched in November 2004 and was fully operational by January
2005. Swift carries three main instruments: the Burst Alert Telescope, the
X-ray Telescope, and the Ultraviolet/Optical Telescope. Swift's gamma-ray
detector, the Burst Alert Telescope, provides the rapid initial location,
was built primarily by the NASA Goddard Space Flight Center in Greenbelt
and Los Alamos National Laboratory, and was constructed at GSFC. Swift's
X-Ray Telescope and UV/Optical Telescope were developed and built by
international teams led by Penn State and drew heavily on each
institution's experience with previous space missions. The X-ray Telescope
resulted from Penn State's collaboration with the University of Leicester
in England and the Brera Astronomical Observatory in Italy. The
Ultraviolet/Optical Telescope resulted from Penn State's collaboration
with the Mullard Space Science Laboratory of the University
College-London. These three telescopes give Swift the ability to do almost
immediate follow-up observations of most gamma-ray bursts because Swift
can rotate so quickly to point toward the source of the gamma-ray signal.
[NOTE: Images and movies supporting this release are available at
http://www.science.psu.edu/alert/Burrows3-2006.htm ]