Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fermi's Large Area Telescope Sees Surprising Flares in Crab Nebula

07.01.2011
The Crab Nebula, one of our best-known and most stable neighbors in the winter sky, is shocking scientists with its propensity for fireworks—gamma-ray flares set off by the most energetic particles ever traced to a specific astronomical object. The discovery, reported today by scientists working with two orbiting telescopes, is leading researchers to rethink their ideas of how cosmic particles are accelerated.

"We were dumbfounded," said Roger Blandford, who directs the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the Department of Energy's SLAC National Accelerator Laboratory and Stanford University. "It's an emblematic object," he said. The Crab Nebula, also known as M1, was the first astronomical object catalogued in 1771 by Charles Messier. "It's a big deal historically," Blandford continued, "and we're making an amazing discovery about it."

Blandford was part of a KIPAC team led by scientists Rolf Buehler and Stefan Funk that used observations from the Large Area Telescope, one of two primary instruments aboard NASA's Fermi Gamma-ray Space Telescope, to confirm one flare and discover another. Their report was posted online today in Science Express alongside a report from the Italian orbiting telescope Astro-rivelatore Gamma a Immagini LEggero, or AGILE, which also detected gamma-ray flares in the Crab Nebula.

The Crab Nebula, and the rapidly spinning neutron star that powers it, are the remnants of a supernova explosion documented by Chinese and Middle Eastern astronomers in 1054. After shedding much of its outer gases and dust, the dying star collapsed into a pulsar, a super-dense, rapidly spinning ball of neutrons. The Crab Nebula's pulsar emits a pulse of radiation every 33 milliseconds, like clockwork.

Though it's only 10 miles across, the amount of energy the pulsar releases is enormous, lighting up the Crab Nebula until it shines 75,000 times more brightly than the sun. Most of this energy is contained in a particle wind of energetic electrons and positrons traveling close to the speed of light. These electrons and positrons interact with magnetic fields and low-energy photons to produce the famous glowing tendrils of dust and gas Messier mistook for a comet over 200 years ago.

The particles are even forceful enough to produce the gamma rays the LAT normally observes during its regular surveys of the sky. But those particles did not cause the dramatic flares.

Each of the two flares the LAT observed lasted a few days before the Crab Nebula's gamma-ray output returned to more normal levels. According to Funk, the short duration of the flares points to synchrotron radiation, or radiation emitted by electrons accelerating in the magnetic field of the nebula, as the cause. And not just any accelerated electrons: the flares were caused by super-charged electrons of up to 1015 electron volts, or 10 quadrillion electron volts, approximately 1,000 times more energetic than the protons accelerated by the Large Hadron Collider in Europe, the world's most powerful man-made particle accelerator, and more than 15 orders of magnitude greater than photons of visible light.

"The strength of the gamma-ray flares shows us they were emitted by the highest-energy particles we can associate with any discrete astrophysical object," Funk said.

Not only are the electrons surprisingly energetic, added Buehler, but, "the fact that the intensity is varying so rapidly means the acceleration has to happen extremely fast." This challenges current theories about the way cosmic particles are accelerated. These theories cannot easily account for the extreme energies of the electrons or the speed with which they're accelerated.

The discovery of the Crab Nebula's gamma-ray flares raises one obvious question: how can the nebula do that? Obvious question, but no obvious answers. The KIPAC scientists all agree they need a closer look at higher resolutions and in a variety of wavelengths before they can make any definitive statements. The next time the Crab Nebula flares, the Fermi LAT team will not be the only team gathering data. They'll need all the help they can get to decipher the mysteries of the Crab Nebula

"We thought we knew the essential ingredients of the Crab Nebula," Funk said, "but that's no longer true. It's still surprising us."

The Fermi Gamma-ray Space Telescope was constructed through an astrophysics and particle physics partnership developed by NASA in collaboration with the U.S. Department of Energy Office of Science, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States. SLAC National Accelerator Laboratory managed construction of the LAT and now plays the central role in science operations, data processing and making scientific data available to collaborators for analysis.

SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science.

Melinda Lee | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

From rocks in Colorado, evidence of a 'chaotic solar system'

23.02.2017 | Physics and Astronomy

'Quartz' crystals at the Earth's core power its magnetic field

23.02.2017 | Earth Sciences

Antimicrobial substances identified in Komodo dragon blood

23.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>