Los Alamos Hosts Gamma-Ray Burst Anniversary Conference

Scientists from around the world
are convening this week to debate and share their latest research at
the Gamma-Ray Burst 2003 Symposium in Santa Fe, September 9 – 12,
2003. Los Alamos National Laboratory is sponsoring the symposium, the
largest of its type to date.

Coordinated by the Space and Remote Sensing Sciences Group at Los
Alamos, the conference marks the 30th anniversary of the discovery
gamma-ray bursts (GRBs) in 1973 by Los Alamos National Laboratory
scientists. “This is the beginning of a new era in GRB research,”
said Marc Kippen, a conference organizer. “This will be the first
major conference discussing the fantastic discovery of GRB 030329,
which unambiguously establishes that at least some gamma-ray bursts
are produced in supernova-like explosions called ‘hypernovae.’ After
decades of wild speculation, theorists finally have a firm footing
from which to start.”

Nearly 250 physicists and astrophysicists will be on hand for the
event to present and debate observations and theories of the relation
of the gamma-ray bursts to black holes, neutron stars and other
strange astronomical objects. The meeting is at the Santa Fe Hilton,
100 Sandoval Street, and media are welcome to attend. A press
conference, with panelists reporting new results that evolve during
the conference, will be scheduled for the latter part of the week.
Detailed contact information for those wishing to teleconference will
be provided in a later media advisory.

Gamma rays, the most energetic form of light known, are emitted from
the bursts as brightly as 100 million billion stars. Among the
subject areas to be addressed this week will be GRBs as probes of
cosmology and the origins of the universe; their relationships to
supernovae; automated robot observing systems; ultra high-energy
gamma rays, neutrinos, gravity waves and the global properties of the
bursts.

“There is a growing consensus that gamma-ray bursts are a rare type
of supernova, the hypernova, that involves jets of material that beam
the gamma rays, ” said Laboratory Fellow Edward Fenimore, lead
organizer of the conference. “When Earth is in that beam, the burst
is so bright that we can see the gamma-ray bursts from across the
entire universe.”

This beaming will be a major topic at the conference. Theoreticians
will try to explain the beaming, observers will report efforts to
measure it and others will exploit the beams to measure the universe
when it was very young.

“Another intriguing topic will be the relation between gamma-ray
bursts and the so-called X-ray flashes that appear to be related to
the same type of explosion,” said Kippen. “They could provide the
link needed to more clearly understand how the bursts are generated.”

These transient bursts of gamma rays from space were discovered in
1973 by Ray Klebesadel and other Los Alamos scientists using data
acquired earlier by detectors aboard the Vela treaty-verification
satellites. Astrophysicist Stirling Colgate had suggested searching
the Vela data for signs of gamma rays emitted during the initial
stages of a supernova. Instead of supernovae, they found gamma-ray
bursts, which for a few seconds can outshine the rest of the sky at
these energies; the origin of the bursts remains a puzzle to
astronomers to the present day and forms the basis of energetic
debate on the subject.

In 1991, NASA launched the Compton Gamma Ray Observatory (CGRO),
carrying four instruments whose data led scientists from the Marshall
Space Flight Center to announce that the bursts were coming equally
from all directions, which is expected for sources that lie at
distances near the edge of the universe. The CGRO re-entered Earth’s
atmosphere in 2000 at the end of its mission.

A number of other GRB-detection systems have since been launched,
among them the HETE-2 satellite, launched in 2000. The HETE program
is an international collaboration led by the Center for Space
Research at the Massachusetts Institute of Technology for NASA. HETE
has 12 networked computers with a sophisticated message architecture
that allows the instruments to interact with each other and influence
each other’s behavior – probably the most complex software ever flown
on a satellite of this size. HETE-2 is equipped with instruments
sensitive to gamma- and X-radiation. These instruments share a common
field of view of ~1.5 steradians, span a detectable energy range of
about three decades and are capable of immediate inter-instrument
communication.

“Much of the progress that underpins the progress at this conference
comes from the HETE satellite,” said Fenimore. “What is new is that
HETE is routinely locating gamma-ray bursts fast enough and
accurately enough that ground-based telescopes can locate the galaxy
associated with the gamma-ray bursts before they fade away. This
allowed the discovery of a particular burst (GRB030329, occurring on
March 3, 2003) that also contained the unmistaken signature of a rare
type of supernova.”

The Italian Beppo-SAX satellite, which carries sensitive
instrumentation from The Netherlands, also is playing an important
role, along with the Hubble Space Telescope and powerful radio
telescopes in New Mexico, the 10-meter Keck Telescope in Hawaii and
the 6-meter telescope at Russia’s Special Astrophysical Observatory.

Gamma-ray bursts are unpredictable, high-level emissions of gamma
rays originating billions of light years from Earth, ranging in
duration from 30 milliseconds to several minutes. These bursts are
usually brighter and more energy-intense than the combination of all
other sources of gamma rays within the universe added together.

The sources of gamma-ray bursts and their causes are still unknown by
astronomers, but it is hoped that new research to be presented this
week at the GRB2003 Symposium will bring scientists closer to
answering these questions. The conference Web site is at
http://grb2003.lanl.gov/.

Los Alamos National Laboratory is operated by the University of
California for the National Nuclear Security Administration (NNSA) of
the U.S. Department of Energy and works in partnership with NNSA’s
Sandia and Lawrence Livermore national laboratories to support NNSA
in its mission.

Los Alamos develops and applies science and technology to ensure the
safety and reliability of the U.S. nuclear deterrent; reduce the
threat of weapons of mass destruction, proliferation and terrorism;
and solve national problems in defense, energy, environment and
infrastructure.