gamma-ray pulsars

gamma-ray pulsars

The improved sensitivity of instrumentation on the Compton Gamma Ray Observatory has shown that pulsars can be powerful gamma-ray emitters. The gamma radiation is thought to originate in the star's outer magnetosphere, and in some cases it appears that a large fraction of the spin-down energy of the pulsar is emitted as pulsed gamma radiation. Geminga is now known to be a γ-ray pulsar, and, with a 180° phase separation of the two pulses, is thought to be an extreme case; nearly 100% of the available energy is emitted as γ-rays and the dipole magnetic field is inclined at a very large angle (> 65°) to the spin axis.
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The First Fermi Large Area Telescope catalog of gamma-ray pulsars.
Among specific topics are the decomposition of the optical polarization components of the Crab pulsar and its nebula, the analysis of single pulses from radio pulsars at high observing frequencies, the population synthesis of normal radio and gamma-ray pulsars using Markov chain Monte Carlo techniques, symmetry energy effects in the neutron star properties, and radio timing observations of four gamma-ray pulsars at Nanshan.
This difference may appear negligibly small, but it's the largest glitch ever measured for a pure gamma-ray pulsar," explained Bruce Allen, Director of the Albert Einstein Institute (AEI), whose team announced the discovery of nine new Fermi gamma-ray pulsars, back in November 2011.
Using ingenious data analysis methods, researchers from the Max Planck Institutes for Gravitational Physics (MPG) and for Radio Astronomy (MPIfR), in an international collaboration, dug a very special gamma-ray pulsar out of data from the Fermi Gamma-ray Space Telescope.
At the same time, another team has located nine new gamma-ray pulsars in Fermi data, using improved analytical techniques.
We adapted methods originally devised for studying gravitational waves to the problem of finding gamma-ray pulsars, and we were quickly rewarded," said Bruce Allen, director of the Max Planck Institute for Gravitational Physics in Hannover, Germany.
If Fermi continues to find gamma-ray-only pulsars at such a high rate, it could indicate that the galaxy has as many gamma-ray pulsars as radio pulsars, says Caltech's Shri Kulkarni.
These types of neutron stars are exciting in their own right, observable as the beautiful radio and gamma-ray pulsars that spin like lighthouses with exquisite regularity.
The other two gamma-ray pulsars emit their gamma flashes twice during each rotation; scientists have speculated that one flash comes from the north magnetic pole, the other from the south.
Fermi has truly unprecedented power for discovering and studying gamma-ray pulsars," said Paul Ray of the Naval Research Laboratory in Washington.
This revelation will radically alter today's pulsar census as tomorrow's high-resolution gamma-ray instruments find more of these gamma-ray pulsars.
The Fermi-LAT Collaboration is publishing a new study that picks out gamma-ray pulsar candidates from 7 1/2 years of Fermi observations.