Chandra discovers relativistic pinball machine

Nov 15, 2006
Chandra discovers relativistic pinball machine
This extraordinarily deep Chandra image shows Cassiopeia A (Cas A, for short), the youngest supernova remnant in the Milky Way. New analysis shows that this supernova remnant acts like a relativistic pinball machine by accelerating electrons to enormous energies. The blue, wispy arcs in the image show where the acceleration is taking place in an expanding shock wave generated by the explosion. The red and green regions show material from the destroyed star that has been heated to millions of degrees by the explosion. Credit: NASA/CXC/UMass Amherst/M.D.Stage et al.

New clues about the origins of cosmic rays, mysterious high-energy particles that bombard the Earth, have been revealed using NASA's Chandra X-ray Observatory. An extraordinarily detailed image of the remains of an exploded star provides crucial insight into the generation of cosmic rays.

For the first time, astronomers have mapped the rate of acceleration of cosmic ray electrons in a supernova remnant. The new map shows that the electrons are being accelerated at close to the theoretically maximum rate. This discovery provides compelling evidence that supernova remnants are key sites for energizing charged particles.

The map was created from an image of Cassiopeia A, a 325-year-old remnant produced by the explosive death of a massive star. The blue, wispy arcs in the image trace the expanding outer shock wave where the acceleration takes place. The other colors in the image show debris from the explosion that has been heated to millions of degrees.

"Scientists have theorized since the 1960s that cosmic rays must be created in the tangle of magnetic fields at the shock, but here we can see this happening directly," said Michael Stage of the University of Massachusetts, Amherst. "Explaining where cosmic rays come from helps us to understand other mysterious phenomena in the high-energy universe."

Examples are the acceleration of charged particles to high energies in a wide variety of objects, ranging from shocks in the magnetosphere around Earth to awesome extragalactic jets that are produced by supermassive black holes and are thousands of light years in length.

Scientists had previously developed a theory to explain how charged particles can be accelerated to extremely high energies – traveling at almost the speed of light – by bouncing back and forth across a shock wave many times.

"The electrons pick up speed each time they bounce across the shock front, like they're in a relativistic pinball machine," said team member Glenn Allen of the Massachusetts Institute of Technology (MIT), Cambridge. "The magnetic fields are like the bumpers, and the shock is like a flipper."

In their analysis of the huge data set, the team was able to separate the X-rays coming from the accelerating electrons from those coming from the heated stellar debris. The data imply that some of these electrons are accelerated at a rate close to the maximum predicted by theory. Cosmic rays are composed of electrons, protons, and ions, of which only glow from electrons is detectable in X-rays. Protons and ions, which constitute the bulk of cosmic rays, are expected to behave similarly to the electrons.

"It's exciting to see regions where the glow produced by cosmic rays actually outshines the 10-million-degree gas heated by the supernova's shock waves," said John Houck, also of MIT. "This helps us understand not only how cosmic rays are accelerated, but also how supernova remnants evolve."

As the total energy of the cosmic rays behind the shock wave increases, the magnetic field behind the shock is modified, along with the character of the shock wave itself. Researching the conditions in the shocks helps astronomers trace the changes of the supernova remnant with time, and ultimately better understand the original supernova explosion.

Source: Chandra X-ray Center

Explore further: Hubble view: Wolf-Rayet stars, intense and short-lived

Related Stories

Cosmic ray observatory to expand

Jun 15, 2015

Physicists plan a $6.4 million expansion of the $25 million Telescope Array observatory in Utah so they can zero in on a "hotspot" that seems to be a source of the most powerful particles in the universe: ...

Chandra finds evidence for serial black hole eruptions

Jun 10, 2015

Astronomers have used NASA's Chandra X-ray Observatory to show that multiple eruptions from a supermassive black hole over 50 million years have rearranged the cosmic landscape at the center of a group of ...

Unlocking the secrets of star creation

Apr 30, 2015

On April 1, 1995, the Hubble Space Telescope (link is external), now celebrating its 25th anniversary, captured the famous images of the "Pillars of Creation" in the Eagle Nebula. Twenty years later to the ...

Image: Chandra's view of the Tycho Supernova remnant

Jul 25, 2014

More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of ...

Recommended for you

Hubble view: Wolf-Rayet stars, intense and short-lived

Jul 03, 2015

This NASA/European Space Agency (ESA) Hubble Space Telescope picture shows a galaxy named SBS 1415+437 (also called SDSS CGB 12067.1), located about 45 million light-years from Earth. SBS 1415+437 is a Wolf-Rayet ...

NASA image: Stellar sparklers that last

Jul 03, 2015

While fireworks only last a short time here on Earth, a bundle of cosmic sparklers in a nearby cluster of stars will be going off for a very long time. NGC 1333 is a star cluster populated with many young ...

Light echo helps researchers map out parts of galaxy

Jul 03, 2015

Thousands of years before humans invented agriculture, a bright burst of X-rays left the dense neutron star Circinus X-1, located in the faint Southern constellation Circinus. A year and a half ago, those ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

TheJ3ss3
not rated yet Jun 29, 2009
That deaf, dumb and blind kid sure plays a mean pinball!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.