Chandra examines quadrillion-volt pulsar

by Marshall Space Flight Center

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The high-voltage environment of one of the most energetic and strongly magnetized pulsars known has been surveyed by NASA's Chandra X-ray Observatory. A team of astronomers found a powerful jet of high-energy particles extending over a distance of 20 light years and bright arcs believed to be due to particles of matter and anti-matter generated by the pulsar.

The team of US, Canadian, and Japanese scientists pointed Chandra at the rapidly spinning neutron star B1509-58, located 19,000 light years away in the constellation of Circinus, for over five hours. These results were announced at the "Two Years of Science with Chandra" symposium in Washington, D.C.

“Jets and arcs on this vast scale have never been seen in any other pulsar,” said Bryan Gaensler of the Smithsonian Astrophysical Observatory. “The spectacular images we have obtained of this source are letting us test theories as to how pulsars unleash so much energy.”

The features seen with Chandra give the scientists insight into the process by which voltages of more than 7000 trillion volts are created around rotating neutron stars (the dense remnants of supernova explosions) and how these extreme voltages affect their environment. B1509-58 is of particular interest because it has a much stronger magnetic field than the Crab Nebula pulsar, which exhibits similar features on a much smaller scale.

The general picture emerging from these results is that high-energy particles of matter and antimatter are streaming away from the neutron star along its poles and near its equator. The particles leaving the poles produce the jets; astronomers speculate that only one side of the jet is apparent in B1509-58, indicating that this one side is beamed in our direction, while the other is rushing away.

"Until this observation, no one knew for sure whether such tremendous voltages and energy outputs were a trademark of all pulsars, or if the Crab was an oddball," said Vicky Kaspi of McGill University in Montreal. "Now thanks to Chandra, it is becoming clear that pulsars are stupendous cosmic power plants."

The arcs are thought to be due to shock waves in matter flowing away from the equator of the pulsar. By measuring the position and width of these arcs, the team estimated the intensity of the magnetic field, and the rate at which the pulsar is pumping high-energy particles into the space around it.

"The X-ray images give us evidence that the pulsar not only accelerates particles efficiently,” said Jonathan Arons of the University of California at Berkeley, “but it gives them energy comparable to the highest energies found in the cosmic rays which continuously bombard the Earth."

In addition, the team determined that a bright cloud of X-ray emission about 25 light years from the pulsar is due to multi-million degree gas. This hot cloud was probably produced as material ejected by the supernova collided with cooler gas in interstellar space.

Other members of the B1509-58 research team included Michael Pivovaroff (ThermaWave Inc), Nobuyuki Kawai (Tokyo Institute of Technology) and Keisuke Tamura (Nagoya University).

Chandra observed B1509-58 with its Advanced CCD Imaging Spectrometer (ACIS) instrument, which was developed for NASA by Pennsylvania State University, University Park, and Massachusetts Institute of Technology, Cambridge. NASA's Marshall Space Flight Center in Huntsville, Ala, manages the Chandra program, and TRW, Inc., Redondo Beach, Calif., is the prime contractor for the spacecraft. The Smithsonian's Chandra X-ray Center controls science and flight operations from Cambridge, Mass.

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