Nav: Home

Dissecting a stellar explosion

April 03, 2009

Integral has captured one of the brightest gamma-ray bursts ever seen. A meticulous analysis of the data has allowed astronomers to investigate the initial phases of this giant stellar explosion, which led to the ejection of matter at velocities close to the speed of light. In particular, the astronomers believe that the explosion lifted a piece of the central engine's magnetic field into space.

On 19 December 2004, the blast from an exploding star arrived at Earth. ESA's Integral satellite, an orbiting gamma-ray observatory, recorded the entire event, providing information for what may prove to be one of the most important gamma-ray bursts (GRBs) seen in recent years. As the data was collected, astronomers saw the 500-second-long burst rise to extraordinary brilliance.

"It is in the top 1% of the brightest GRBs we have seen," says Diego Götz, CEA Saclay, France, who headed the investigation.

The brightness of the event, known as GRB 041219A, has allowed the team to perform a painstaking investigation to extract a property known as the polarisation of the gamma rays. The team have shown that the gamma rays were highly polarised and varied tremendously in level and orientation.

Polarisation refers to the preferred direction in which the radiation wave oscillates. Polaroid sunglasses work with visible light by letting through only a single direction of polarisation, blocking most of the light from entering our eyes.

The blast from a GRB is thought to be produced by a jet of fast-moving gas bursting from near the central engine; probably a black hole created by the collapse of the massive star. The polarisation is directly related to the structure of the magnetic field in the jet. So it is one of the best ways for astronomers to investigate how the central engine produces the jet. There are a number of ways this might happen.

In the first scenario, the jet carries a portion of the central engine's magnetic field into space. A second involves the jet generating the magnetic field far from the central engine. A third concerns the extreme case in which the jet contains no gas just magnetic energy, and a fourth scenario entails the jet moving through an existing field of radiation.

In each of the first three scenarios, the polarisation is generated by what is called synchrotron radiation. The magnetic field traps particles, known as electrons, and forces them to spiral, releasing polarised radiation. In the fourth scenario, the polarisation is imparted through interactions between the electrons in the jet and photons in the existing radiation field.

Götz believes that the Integral results favour a synchrotron model and, of those three, the most likely scenario is the first, in which the jet lifts the central engine's magnetic field into space. "It is the only simple way to do it," he says.

What Götz would most like to do is measure the polarisation for every GRB, to see whether the same mechanism applies to all. Unfortunately, many GRBs are too faint for the current instrumentation to succeed. Even the state-of-the-art IBIS instrument on Integral can only record the polarisation state of gamma rays if a celestial source is as bright as GRB 041219A.

"So, for now we just have to wait for the next big one," he says.
-end-


European Space Agency

Related Magnetic Field Articles:

Understanding stars: How tornado-shaped flow in a dynamo strengthens the magnetic field
A new simulation based on the von-Kármán-Sodium (VKS) dynamo experiment takes a closer look at how the liquid vortex created by the device generates a magnetic field.
'Quartz' crystals at the Earth's core power its magnetic field
Scientists at the Earth-Life Science Institute at the Tokyo Institute of Technology report in Nature (Fen.
Brightest neutron star yet has a multipolar magnetic field
Scientists have identified a neutron star that is consuming material so fast it emits more x-rays than any other.
Confirmation of Wendelstein 7-X magnetic field
Physicist Sam Lazerson of the US Department of Energy's Princeton Plasma Physics Laboratory has teamed with German scientists to confirm that the Wendelstein 7-X fusion energy device called a stellarator in Greifswald, Germany, produces high-quality magnetic fields that are consistent with their complex design.
High-precision magnetic field sensing
Scientists have developed a highly sensitive sensor to detect tiny changes in strong magnetic fields.
Brilliant burst in space reveals universe's magnetic field
Scientists have detected the brightest fast burst of radio waves in space to date -- locating the source of the event with more precision than previous efforts.
Optical magnetic field sensor can detect signals from the nervous system
The human body is controlled by electrical impulses in the brain, the heart and nervous system.
What did Earth's ancient magnetic field look like?
New work from Carnegie's Peter Driscoll suggests Earth's ancient magnetic field was significantly different than the present day field, originating from several poles rather than the familiar two.
Just what sustains Earth's magnetic field anyway?
Earth's magnetic field shields us from deadly cosmic radiation, and without it, life as we know it could not exist here.
Ironing out the mystery of Earth's magnetic field
The Earth's magnetic field has been existing for at least 3.4 billion years thanks to the low heat conduction capability of iron in the planet's core.

Related Magnetic Field Reading:

Earth's Magnetic Field Secrets: An Illusion Mixed With Reality
by Dennis Brooks (Author)

Magnetic Fields: Expanding American Abstraction, 1960s to Today
by Valerie Cassel Oliver (Author), Lowery Stokes Sims (Author), Erin Dziedzic (Editor), Melissa Messina (Editor)

NOW 2 kNOW Electro-Magnetic Fields
by Dr. T G D'Alberto (Author)

Know Your Magnetic Field: Change Your Thinking, Change Your Life.
by William E. Gray (Author)

Power Tools for Health: How Pulsed Magnetic Fields (Pemfs) Help You
by Msc William Pawluk MD (Author), Caitlin Layne (Author)

Conversations on Electric and Magnetic Fields in the Cosmos (Princeton Series in Astrophysics)
by Eugene N. Parker (Author)

The Automatic Message, the Magnetic Fields, the Immaculate Conception (Atlas Anti-Classics)
by Andre Breton (Author), Philippe Soupault (Author), Paul Eluard (Author), David Gascoyne (Translator), Antony Melville (Translator), Jon Graham (Translator)

Numerical Computation of Electric and Magnetic Fields
by Charles W. Steele (Author)

PEMF - The Faster, More Effective Way to Relieve Your Pain: Pulsed Electro Magnetic Field Therapy
by Alane Paulley

The Magnetic Fields
by André Breton (Author), Philippe Soupault (Author), David Gascoyne (Translator)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Hacking The Law
We have a vision of justice as blind, impartial, and fair — but in reality, the law often fails those who need it most. This hour, TED speakers explore radical ways to change the legal system. Guests include lawyer and social justice advocate Robin Steinberg, animal rights lawyer Steven Wise, political activist Brett Hennig, and lawyer and social entrepreneur Vivek Maru.
Now Playing: Science for the People

#495 Earth Science in Space
Some worlds are made of sand. Some are made of water. Some are even made of salt. In science fiction and fantasy, planet can be made of whatever you want. But what does that mean for how the planets themselves work? When in doubt, throw an asteroid at it. This is a live show recorded at the 2018 Dragon Con in Atlanta Georgia. Featuring Travor Valle, Mika McKinnon, David Moscato, Scott Harris, and moderated by our own Bethany Brookshire. Note: The sound isn't as good as we'd hoped but we love the guests and the conversation and we wanted to...