Email: hellings@physics.montana.edu
Phone: 406-994-1693
Fax: 406-994-4452
EPS Room 222, MSU, Bozeman, 59717-3840, MT

Biographical Sketch:

To be added later.

Interests:

Research

  1. Tests of relativistic theories of gravity using solar system data. A century of optical transit circle observations of the right ascensions and declinations of the planets, plus several decades of radar and planetary spacecraft range data from earth to the planets are fit to a relativistic model of solar system dynamics. In the process, the values of certain theory-dependent parameters (the so-called Parametrized Post-Newtonian, or PPN, parameters) are solved for. The observed values of these parameters allow one to discriminate between competing theories of gravity. 
  2. Low Frequency (LF) gravitational wave astronomy. Beginning with searches using spacecraft radio tracking data and pulsar timing data, we have worked on the direct detection of gravitational waves. This has included designing a dedicated space mission, OMEGA, that would have had the sensitivity to see gravitational waves from known astronomical sources and from massive black hole events at cosmological distances from the earth. Most recently, the work has centered on developing data processing and data analysis algorithms for the proposed LISA mission.

Selected Publications:

  • Gravitational Wave Detectors in Space, Contemp. Phys. 37 457 (1996).
  • Sensitivity curves for spaceborne gravitational wave interferometers , with Shane L. Larson and William A. Hiscock, Phys. Rev. D 62, 062001 (2000). 
  • Elimination of Clock Jitter Noise in Spaceborn Laser Interferometers , Phys. Rev. D 64 022002 (2001).
  • Angular resolution of space-based gravitational wave detectors , with Thomas A. Moore, Phys. Rev. D 65, 062001 (2002).