Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session A3: Pulsars in the Fermi Era |
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Sponsoring Units: DAP Chair: Maxim Lyutikov, Purdue University Room: Thurgood Marshall South |
Saturday, February 13, 2010 8:30AM - 9:06AM |
A3.00001: Fermi Observations of Gamma-ray Pulsars Invited Speaker: A year and a half after Fermi was launched, the number of known gamma-ray pulsars has increased dramatically. For the first time, a sizeable population of pulsars has been discovered in gamma-ray data alone. For the first time, millisecond pulsars have been confirmed as powerful sources of gamma-ray emission, and a whole population of these objects is seen with the LAT. The remaining gamma-ray pulsars are young pulsars, discovered via an efficient collaboration with radio and X-ray telescopes. It is now clear that a large fraction of the nearby energetic pulsars are gamma-ray emitters, whose luminosity grows with the spin-down energy loss rate. Many previously unidentified EGRET sources turn out to be pulsars. Many of the detected pulsars are found to be powering pulsar wind nebulae, and some are associated with TeV sources. The Fermi LAT is expected to detect more pulsars in gamma rays in the coming years, while multi-wavelength follow ups should detect Fermi-discovered pulsars. The data already revealed that gamma-ray pulsars generally emit fan-like beams sweeping over a large fraction of the sky and produced in the outer magnetosphere. [Preview Abstract] |
Saturday, February 13, 2010 9:06AM - 9:42AM |
A3.00002: Implications of Fermi Observations for Gamma-Ray Pulsar Emission Models Invited Speaker: Pulsars are powerful sources of radiation across the electromagnetic spectrum. This review will highlight some recent theoretical insights into non-thermal, magnetospheric pulsar gamma-ray radiation. These advances have been driven by the huge data infusion provided by NASA's Fermi mission, launched in mid-2008. The LAT instrument on Fermi has afforded the discrimination between polar cap and slot gap/outer gap acceleration zones in young and middle-aged pulsars. Altitude discernment using the highest energy pulsar photons will be addressed, as will inferences of the primary radiation mechanism in the LAT band using phase-resolved spectroscopy, connecting to both polar cap/slot gap and outer gap scenarios. Focuses on curvature radiation and pair creation will be included, as will population trends that may afford probes of the magnetospheric accelerating potential. While the Vela pulsar serves as a principal test case, the geometrical and emission model interpretation of Fermi LAT results for several other young pulsars will also be discussed. An additional brief focus will be the implications of Fermi observations for millisecond pulsars. [Preview Abstract] |
Saturday, February 13, 2010 9:42AM - 10:18AM |
A3.00003: Particle acceleration in pulsar magnetospheres Invited Speaker: Fermi Telescope has dramatically expanded the sample of gamma-ray pulsars. The quality of pulsar light curves and spectra is exceptional, and allows a direct study of the magnetospheric processes that lead to the emission of gamma-rays. I will review the theoretical understanding of pulsar magnetospheres and discuss how gamma-ray light curves and spectra can be used to determine the location of the emitting zones and the geometry of magnetic field. It is now clear that the emission is coming from the outer magnetosphere, where the deviations from dipolar field geometry due to plasma currents must be taken into account. I will discuss the modeling of gamma-ray light curves in plasma-filled (force-free) magnetospheres. The double-peaked nature of the gamma-ray light curves observed by Fermi tells us that the accelerating regions are related to the location of strong currents sheets in plasma-filled magnetosphere. Plasma physics and particle acceleration in these current sheets needs to be understood, and will be strongly constrained by modeling of the phase-resolved spectra from Fermi. Gamma rays carry a significant fraction of spin down energy in pulsars; thus, Fermi observations are probing the heart of the electromagnetic pulsar machine. [Preview Abstract] |
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