Jules P. Halpern Teaching C3273: High-Energy Astrophysics e-mail: jules@astro.columbia.edu Telephone: (212) 854-2554

Research Interests:

Pulsars - I am investigating the extreme physical properties of neutron stars through timing and spectroscopy in X-rays and radio. This reveals their strongest magnetic fields, found in Anomalous X-ray Pulsars (AXPs), as well as their weakest, found in Central Compact Objects (CCOs). Monitoring the transient outbursts of AXPs is leading to an understanding of how their enormous magnetic field energy is converted to X-ray luminosity. In contrast, the relatively inconspicuous CCOs seem to have been born with very weak magnetic fields, and not much rotational energy either. This work makes use of the X-ray observatories Chandra, XMM-Newton, and Swift.

Gamma-ray Sources - The elusive unidentified high-energy gamma-ray sources originally discovered by the EGRET experiment on the Compton Gamma-Ray Observatory (CGRO) turn out to be pulsars and pulsar wind nebulae, supernova remnants, and maybe new classes as well. This subject has expanded into the very high-energy regime with the detection of TeV sources in the Galaxy by the ground-based Cerenkov telescopes H.E.S.S., MAGIC, Milagro. and VERITAS, and has literally "taken off" with the successful deployment of the Fermi Gamma-Ray Space Telescope. I will search for and study the counterparts of the gamma-ray sources at other wavelengths.

Background:

Selected Publications:

• "Spin-down Measurement of PSR J1852+0040 in Kesteven 79: Central Compact Objects as Anti-Magnetars," J.P. Halpern & E.V. Gotthelf, Ap. J. 709, 436 (2010)
• "Gamma-Ray Pulsar Old and New," J.P. Halpern, Science 325, 821 (2009)
  
• "Radio Detection of LAT PSRs J1741-2054 and J2032+4127: No Longer Just Gamma-ray Pulsars." F. Camilo, et al., Ap. J. 705, 1 (2009)
  
• "Discovery of a Highly Energetic X-ray Pulsar Powering HESS J1813-178 in the Supernova Remnant G12.82-0.02," E.V. Gotthelf & J.P. Halpern, Ap. J. (Letters) 700, L158 (2009)
  
• "Discovery of a 112 ms X-ray Pulsar in Puppis A: Further Evidence of Neutron Stars Weakly Magnetized at Birth," E.V. Gotthelf & J. P. Halpern," Ap. J. (Letters) 695, L35 (2009)
  
• "Discovery of High-Energy Gamma-ray Pulsations from PSR J2021+3651 with AGILE,'' J.P. Halpern, F. Camilo, A. Giuliani, E.V. Gotthelf, M.A. McLaughlin, R. Mukherjee, A. Pellizzoni, S.M. Ransom, M.S.E. Roberts, & M. Tavani, Ap. J. (Letters) 688, L33 (2008)
  
• More publications . . .