Mysterious Radio Burst from Magellanic Cloud Stuns & Baffles Astronomers
In a fascinating finding, reminiscent of the extraterrestrial Tycho Monolith blast on the Moon in Arthur C. Clarke's 2001 A Space Odyssey, astronomers using Australia's Parkes telescope have
detected a huge burst of radio energy from the distant universe that
could open up a new field in astrophysics.
The research team, led by Assistant Professor Duncan Lorimer of West Virginia University, reports its discovery today in the online journal Science Express. The intense, single, short-lived blast of radio waves likely occurred some 3 billion light-years from Earth, and it may signal a cosmic crash of two neutron stars, the death throes of a black hole—or something else.
"This is something that's completely unprecedented," said Duncan Lorimer, an astrophysicist at West Virginia University in Morgantown and the National Radio Astronomy Observatory who led the discovery-making team. He noted that radio-emitting pulsars send out similar emissions, but repeat them every few hours.
"Normally the kind of cosmic activity we're looking for at this
distance would be very faint but this was so bright that it saturated
the equipment," said Professor Matthew Bailes of Swinburne University
in Melbourne.
The burst was so bright that at the time it was
first recorded it was dismissed as man-made radio interference. It put
out a huge amount of power (10exp33 Joules), equivalent to a large
(2000MW) power station running for two billion billion years.
"The
burst may have been produced by an exotic event such as the collision
of two neutron stars or be the last gasp of a black hole as it
evaporates completely," Professor Lorimer said. The burst lasted just
five milliseconds.
"We're
confused and excited, but it could open up a whole new research field,"
Lorimer told SPACE.com of the 5-millisecond blip on the cosmic radar
screen. "If we really go after these things, we expect to find out that
a couple hundred of them occur each day."
If the bursts are as frequent as Lorimer's team thinks, and they
indicate the death of black holes or two super-dense neutron stars
violently smacking together, a step toward closure of the universe's
great mystery of gravity may soon come.
The dramatic cosmic
events are predicted to let loose gravity waves that Einstein's theory
of relativity predicts, but the phenomenon has never been directly
observed. LIGO—the Laser Interferometer Gravitational Wave Observatory
based in both Louisiana and Washington state—has been searching for
such waves since it went online in 2002.
The previously undetected radio burst was found in data from a 2001
radio survey of the Small Magellanic Cloud, a nearby dwarf galaxy.
Based on its location, however, Lorimer said the burst almost certainly
did not come from the galaxy.
Lorimer said the emission's offset
location and wide dispersion made it "completely inconsistent" with
that of a nearby object, whether in our own galaxy or the Small
Magellanic Cloud. "We've looked at it for about 90 hours, and it
definitely seems to be a singular event," he said.
Astronomers
originally created the 480-hour-long observation over 20 days to look
for repetitive radio emissions from pulsars, which are thought to be
fast-rotating neutron stars, but the event remained hidden in the data
because no one had set out to find single bursts.
Lorimer
cautioned that it's impossible to say for certain what the radio burst
might indicate at this point, as it is the only one that has been
detected so far.
"We're keeping very open minds about this
thing," Lorimer said, adding that their uncertainty stems from the
inability to pinpoint it to a galaxy or other celestial object that
could reveal some clues to its identity.
So far, the search has left the researchers empty-handed, but it may
be an issue of sensitivity. Lorimer emphasized that the records are
several years old and few radio observatories have the sensitivity to
detect such short bursts.
"Based on the area we looked at, we
think this type of burst may occur at a rate of a couple hundred each
day," Lorimer said. He thinks that whole-sky surveys using
next-generation radio observatories would be needed to detect most of
them.
Although they've found only one burst, the astronomers can estimate how
often they occur. "We'd expect to see a few bursts over the whole sky
every day," said Dr John Reynolds, Officer in Charge at CSIRO's Parkes
Observatory.
"A new telescope being built in Western Australia will be ideal for finding more of these rare, transient events.
"The
Australian SKA Pathfinder, which is going to be built by 2012, will
have a very wide field of view--be able to see a very large piece of
sky--which is exactly what you want for this kind of work," he said.
Posted by Casey Kazan. Adapted from a CSIRO release
Story links:
http://www.space.com/scienceastronomy/070927_new_astronomy.html
http://www.theregister.co.uk/2007/09/28/super_radio_burst/
http://www.physorg.com/news110194718.html
Contact: Andrea Wild
andrea.wild@csiro.au
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