Columbia University 
Astronomy and Astrophysics

David J. Helfand


Telephone: (212) 854-2150

Teaching (Spring 2010):

-Core Curriculum: "Frontiers of Science"

My version of Beethoven's Ninth Symphony, useful for illustrating the limited range of human vision compared to the breadth of information about the Universe reaching us in parts of the electromagnetic outside the visible band, is available for non-commercial use. Both audio and illustrated versions can be downloaded from here.

Research Interests:

- Large-scale structure and AGN in radio surveys
- The origin and evolution of neutron stars and supernova remnants
- Active galactic nuclei and the X-ray background

I have recently completed a radio survey of the Galactic Plane that is 30 times more sensitive and has 30 times the angular resolution of the best existing Plane surveys. MAGPIS (the Multi-Array Galactic Plane Imaging Survey) was designed to complement the GLIMPSE infrared PLane survey withe the Spitzer Space telescope. Earlier, I was involved in another radio survey project, also using the Very Large Array, to construct the equivalent of the Palomar Sky Survey for the radio Universe. Our FIRST Survey, begun in 1993, has produced over 34,000 two-million pixel images covering 9200 square degrees of the sky at 20 cm. The survey is complete for point sources to 1.0 mJy, and each of the ~850,000 radio sources catalogued has a position accurate to better than 1". This unprecedented astrometric accuracy has allowed us to increase the number of optically identified radio sources by more than a factor of 100. We are using the survey to map large scale structure by computing the radio source angular correlation functions, detecting the weak-lensing shear produced by the foreground mass distribution on the distant radio sources, calculating the angular diameter-redshift relation for classical double radio sources, and identifying rich clusters at high redshift using bent-double radio galaxies as tracers of high density environments. We are also conducting a FIRST Bright Quasar Survey which has already led to the discovery of over 1000 new quasars with R<18, the first radio-loud BAL objects, and a high incidence of gravitational lenses. Several other projects using this unique new resource are also underway, including a search for highly obscured quasars. In addition, I continue to pursue a long-standing interest in the evolution of neutron stars and the supernova remnants in which the youngest ones are found. We have several programs approved for observations of synchrotron nebulae their neutron stars with Chandra and Newton. Recent results on the pulsars inVela and 3C58 were of particular interest. In order to increase the number of young remnants known, we have begun a major survey of the Galactic plane with the VLA and XMM Newton, complemented by the MSX mid-IR survey. I also expect to use the new generation of X-ray observatories to address the issue of the contribution of starburst galaxies and AGN to the cosmic X-ray background, and to study the high-redshift clusters we are finding with FIRST.


2008-present.. President, Quest University Canada
2005-present.. Founding Tutor, Quest University Canada
2002-present.. Chair, Department of Astronomy, Columbia University
2003-2009 Co-Director, Columbia Astrophysics Laboratory, Columbia University
1992-present.. Professor, Department of Astronomy, Columbia University
1998-1999 Sackler Distinguished Visiting Astronomer, Cambridge University
1994-1997 Chair, Department of Astronomy, Columbia University
1994-1996 Co-Director, Columbia Astrophysics Laboratory
1992-1993 Visiting Astronomer, Cambridge University
1987-1992 Professor, Department of Physics, Columbia University
1986-1992 Chair, Department of Astronomy, Columbia University
1986-1992 Co-Director, Columbia Astrophysics Laboratory
1984 Visiting Scientist, Danish Space Research Institute
1982-1987 Associate Professor of Physics, Columbia University
1978-1982 Assistant Professor of Astronomy, Columbia University
1977-1978 Research Associate, Department of Physics, Columbia University
1977 Ph.D., The University of Massachusetts (Astronomy)
1977 M.S., The University of Massachusetts (Physics)
1973 A.B., Amherst College (Independent Scholar)

Older selected publications not referenced in the above text:

1996 November 16