Press Release

Researchers think Electrons can “Supernova Surf” at Near Lightspeed

By SpaceRef Editor
November 12, 2001
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Researchers have long been puzzled about the origins of cosmic rays —
high energy particles which move very close to the speed of light. Now
a team of scientists from the UK and Sweden think that an idea for a
particle accelerator first put forward twenty years ago might explain
how high energy cosmic ray electrons are produced close to the remnants
of exploded stars (“supernovae”). These very high speed electrons betray
their presence by emitting “synchrotron” radiation as they gyrate in a
magnetic field. Until now however it has been far from clear why the
electrons are accelerated to such high energies.

Researchers from the University of Warwick, the Culham Science Centre
in Oxfordshire, and Linköping University in Sweden used computer
simulations to investigate the behaviour of electrons in the presence
of a magnetic field and a wave consisting of an oscillating electric
field, and found that, depending on the intensities of the magnetic
field and the wave, and the direction in which the wave is moving,
it is possible for a charged particle, such as an electron, to be
accelerated indefinitely by the wave electric field.

This idea was proposed by physicists Tom Katsouleas and John Dawson at
the University of California Los Angeles in 1983 as a novel method of
producing high energy charged particles in the lab, with the wave being
provided by a laser. The term “surfatron” was coined to describe this
type of accelerator, because the particles ride across the wave front
like surfers riding across an ocean wave.

There are no lasers in supernova remnants, but the Warwick, Culham and
Linköping researchers believe that the rapid expansion of a supernova
remnant into space creates shock waves that accelerate ions. These ions
then generate waves which can play a role similar to that of the laser
in the surfatron concept. The analogy is not exact. For example,
whereas the surfatron laser has only a single wavelength, in the case
of the supernova remnant it is impossible to avoid the generation of
waves with a range of wavelengths: this makes it more likely that
particles will eventually stop gaining energy. However, the
Culham-Warwick-Linköping team has shown that acceleration of electrons
to speeds approaching that of light is still possible in these
circumstances. The Warwick-Culham-Linköping research will be published
in the journal Physical Review Letters in early December.

Note for Editors: The researchers acknowledge funding from the PPARC,
the Department of Trade and Industry, the Commission of the European
Communities, and Naturvetenskapliga forskningsrådet (NFR).

For further information please contact:

Professor Sandra Chapman,

Space and Astrophysics, University of Warwick, UK,

tel 024 7652 3390 fax 024 7669 2016

mobile 07740291984

Peter Dunn, Press Officer

University of Warwick

Tel: 024 76523708


Dr K. G. McClements, UKAEA Culham Division, Culham Science Centre, UK,

tel: +44 1235 463303 fax: +44 1235 463435

Dr M. E. Dieckmann

ITN, University of Linköping, Sweden

Tel: 0046-(0)11 363328

Fax: 0046-(0)11 363270

SpaceRef staff editor.