Astronomers Look Forward to SWIFT Studies of Cataclysmic Explosions

Gamma ray bursts (GRBs) are the most powerful explosions in the Universe, yet
it is only in the last few years that astronomers have started to understand
them. This ongoing quest to solve the mysteries of gamma ray bursts will be
boosted next September when a new US/UK/Italian space observatory, called
Swift, will be launched.

Dr. Julian Osborne (University of Leicester) will describe this exciting
mission and the discoveries that can be expected from Swift on Tuesday
30 March, during the RAS National Astronomy Meeting in Milton Keynes.

At present only one GRB is announced each month on average. Studies of these
dramatic events are also complicated by their short duration and random
location in the sky – GRBs typically last between less than 1 to around
100 seconds.

Although GRBs detected by orbiting spacecraft are now announced
instantaneously, the delay in making observations with X-ray space
observatories and
optical telescopes often lasts many hours, by which time the ‘afterglow’
of the explosion has faded to a shadow of its former self – many
thousands of times fainter than it was initially. This makes it much
more difficult to understand the processes that power these brief but
cataclysmic explosions.

Dedicated to understanding these remarkable, transient events, Swift is quite
unique in its ability to automatically respond as soon as a gamma ray burst
appears. After launch in September, the large area Burst Alert Telescope (BAT)
on Swift will detect around 10 GRBs a month.

When the BAT detects a GRB it will send a request to the onboard spacecraft
control system to turn towards the burst. Within one minute the rapidly slewing
spacecraft will be on-target, allowing its Ultraviolet-Optical Telescope and
X-Ray Telescope to start collecting observations. For the first time,
astronomers will be able to gather numerous observations of GRBs during
their most energetic phase, with the promise of new insights into their
nature.

The Ultraviolet-Optical and X-Ray Telescopes on Swift have major UK
involvement. The Mullard Space Science Laboratory (MSSL) of University
College London has provided the Ultraviolet-Optical telescope, a 30 cm
image-intensified instrument with rapid readout. The X-Ray Telescope’s
camera and other subsystems were provided by the University of Leicester.

These instruments make use of the designs and spare parts from the successful
XMM-Newton observatory, ESA’s cornerstone X-ray facility for which these
groups provided similar instruments. Both MSSL and the University of Leicester
will continue to look after their instruments when Swift is in orbit, and a UK
Swift data centre will be set up at Leicester. They will also be providing
rapid
alerts, checking the Swift results and alerting telescopes around the world
so that astronomers will be able to respond as soon as a GRB is detected.

“It will be a very busy and exciting time when Swift starts finding GRBs,”
said Dr. Osborne. “Swift will tell astronomers about the massive
explosions and the death of stars, both important events in their own right.

“But because the GRBS are so very bright, Swift offers the tantalizing
prospect of seeing the very first generation of stars and may even set the
record
for the most distant objects ever seen. Bright and distant GRBs will also
allow astronomers to ‘X-ray’ all the matter between us and the GRB,
providing important clues to the evolution of the universe.”

NOTES FOR EDITORS:

Gamma rays occupy the highest energy range in the electromagnetic spectrum,
well beyond visible light, ultraviolet and X-rays. They are produced by
extremely energetic particle collisions, the annihilation of matter and by
nuclear
decay (radioactivity). They can travel vast distances through space,
but are absorbed in the Earth’s atmosphere.

Gamma ray bursts outshine the entire universe in the few seconds they glow.
They were discovered in 1967 by U.S. satellites that were monitoring the
nuclear test ban treaty. It was only with the discovery of their afterglows
7 years ago that astronomers started to understand them. Before then, it
was not even possible to tell if they were near the Solar System or in the
farthest reaches of the Universe.

It is now known that most of the GRBs are very distant, and probably the
result of the creation of a black hole when a very massive star reaches
the end of
its life in a supernova explosion. Two types of GRB are recognised, but very
little is known about those that have very short lives, since no afterglow
from them has ever been seen.

The 2004 RAS National Astronomy Meeting is hosted by the Open University, and
sponsored by the Royal Astronomical Society and the UK Particle Physics and
Astronomy Research Council (PPARC).

CONTACT:

On 30 and 31 March, Dr. Osborne can be contacted via the NAM press office
(see above).

Normal contact details:

Dr. Julian Osborne

Dept of Physics & Astronomy

University of Leicester

Leicester LE1 7RH

Tel: +44 (0)116-252-3598

Fax: +44 (0)116-252-3311

E-mail: julo@star.le.ac.uk

FURTHER INFORMATION AND IMAGES CAN BE FOUND ON THE WEB AT:

NASA Swift: http://swift.gsfc.nasa.gov/public/

Leicester GRB news: http://www.star.le.ac.uk/~julo/news.html

Leicester Swift: http://www.src.le.ac.uk/projects/swift/

MSSL Swift:
http://www.mssl.ucl.ac.uk/pages/general/projects/swift/SWIFT6.html

ESA XMM-Newton: http://www.esa.int/export/esaSC/120385_index_0_m.html