 |
David H. Roberts roberts@brandeis.edu
William
R. Kenan, Jr. Professor of
Astrophysics |
David Roberts is engaged in high resolution astronomical observations of active galaxies (quasars, radio and Seyfert galaxies, and BL Lacertae objects) at wavelengths covering the entire electromagnetic spectrum. This is carried out with the Very Large Array and the Very Long Baseline Array, including its extension into space with the HALCA satellite. He is particularly interested in linear polarization observations in order to study the magnetic field structure in active galactic nuclei. Professor Roberts is a member of the Brandeis Astrophysics group.
Recent Ph.D. Students:
George Moellenbrock (1999) “ VLBA Polarization Observations of Gamma-Ray Blazars at 15 and 22 GHz ” Present Position: Assistant Scientist, AIPS + + Project, National Radio Astronomy Observatory, Socorro, NM
Joanne Attridge (1999) “ Magnetic Field Structures in the Parsec-Scale Radio Jets of Blazars” Present Position: Senior Systems Engineer, Integrated Defense Systems, Raytheon Electronic Systems, Bedford, MA
Sample of Recent
Publications:
"A
Multi-Frequency VLBI Study of the CSS 3C309.1"
(with S.E. Aaron and J.F.C. Wardle) in IAU
Colloquium 164: Radio Emission from Galactic and
Extragalactic Compact Radio Sources, ed. J.A.
Zensus, J.M. Wrobel, and G.B. Taylor, p. 105
(1998).
"VLBA Polarization of a Large Sample of Blazars" (with J.M. Attridge, D.C. Homan and J.F.C. Wardle) in IAU Colloquium 164: Radio Emission from Galactic and Extragalactic Compact Radio Sources, ed. J.A. Zensus, J.M. Wrobel, and G.B. Taylor, p. 159-160 (1998).
"Detection of Circular Polarization in 3C84 and 3C279 with the VLBA" (with D.C. Homan, R. Ojha and J.F.C. Wardle) in IAU Colloquium 164: Radio Emission from Galactic and Extragalactic Compact Radio Sources, ed. J.A. Zensus, J.M. Wrobel, and G.B. Taylor, p. 123-124 (1998).
"Evolution of the Parsec-Scale Structures of Sources with Rapidly Variable Polarization" (with R. Ojha, D.C. Homan, and J.F.C. Wardle) in IAU Colloquium 164: Radio Emission from Galactic and Extragalactic Compact Radio Sources, ed. J.A. Zensus, J.M. Wrobel, and G.B. Taylor, p. 127-128 (1998).
"The Detection of Parsec-Scale Circular Polarization in the Quasar 3C279; Evidence for Electron-Positron Jets" (with J.F.C. Wardle, D.C. Homan, and R. Ojha), Nature, 395, 457-462 (1998).
"The Very Long Baseline Interferometric Polarization Structure of 3C 345 at l =2.8 cm" (with D.C. Gabuzda, A.J. Mioduszewski and J.F.C. Wardle), Monthly Notices of the Royal Astronomical Society, 303, 515-520 (1999).
"Radio Jet - Ambient Medium Interaction on Parsec Scales in the Blazar 1055+018" (with J.M. Attridge and J.F.C. Wardle) in Astrophysical Journal (Letters), 518, L87-L90 (1999).
"Polarimetry with the Very Long Baseline Array," in Radio Interferometry: The Saga and the Science, Proceedings of a Symposium Honoring Barry Clark at 60, ed. D.G. Finley and W.M. Goss (National Radio Astronomy Observatory, ISBN 0-9700411-0-1), 265-273 (2000).