Position Type 
2003 - Present



One of the things that excites me most about Physics is our continuing struggle to develop a better understanding of how the world works at a fundamental level. We Physicists also work to apply that understanding to complex, real world problems. For me, one of the great pleasures of Physics is finding creative ways to address these challenges. I enjoy teaching Physics and Astronomy at all levels in our curriculum.

B.S., University of Maine; M.A., Ph.D., Brandeis University


Astrophysics — Studies active galaxies and relativistic jets from supermassive black holes using a variety of techniques, including radio interferometry, polarimetry, radiative transfer, and simulations.

Black Holes and Cosmic Jets

I study distant active galaxies. Active galaxies are extremely energetic galaxies, giving off so much energy that they can be viewed from billions of light years away. All of the unusual, energetic behavior in an active galaxy can ultimately be traced to its galactic center or nucleus, a region only a few light years across. These objects are therefore often called "Active Galactic Nuclei" or "AGN" for short. It is now believed that all AGN have, at their center, a super-massive black hole that is millions or even billions of times the mass of our Sun. Matter falling inward toward the black hole dramatically releases energy to generate the phenomena we observe.

There is a sub-class of AGN that have strong jets of plasma which stream outward from the galactic nucleus and are visible at radio wavelengths. These radio jets come in a number of morphologies with the most spectacular maintaining collimated flows for tens or even hundreds of thousands of light-years before terminating at hotspots in large, inflated radio lobes. I study these jets to understand their physical properties and how they are created by the super-massive black hole and accretion disk of in-falling matter at the center of the galaxy.




  • Inverse Depolarization: A Potential Probe of Internal Faraday Rotation and Helical Magnetic Fields in Extragalactic Radio Jets”, by Homan, D. C. (2012) The Astrophysical Journal Letters vol. 747, p. L24
  • Relativistic Beaming and Gamma-Ray Brightness of Blazars”, by Savolainen, T., Homan, D. C., Hovatta, T., Kadler, M., Kovalev, Y. Y.;,Lister, M. L., Ros, E., & Zensus, J. A. (2010)Astronomy & Astrophysics vol. 512, id.A24
  • MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VII. Blazar Jet Acceleration”, by Homan, D. C., Kadler, M., Kellermann, K. I., Kovalev, Y. Y., Lister, M. L. Ros, E., Savolainen, T., & Zensus, J. A. (2009) The Astrophysical Journal vol. 706, p. 1253