Prof. Marscher’s research group studies the extremely energetic plasma jets that emanate from a class of AGN called “blazars” (radio-bright quasars and BL Lacertae objects, whose brightness tends to be highly variable and whose continuum spectra are non-thermal). Ultra-massive (over a billion solar masses in some cases) black holes residing at the centers of many galaxies power blazars as they accrete matter from their surroundings. The black holes swallow most of the gas and dust, but expel a small fraction in winds and jets of high-energy particles along the rotation axes, at flow speeds very close to the speed of light. Such relativistic motions create illusions of faster-than-light speeds and beams the radiation emitted such that observers viewing the jet almost along the axis measure a very high brightness that varies on timescales as short as hours or even minutes. Prof. Marscher’s group focuses on monitoring the changing brightness and polarization at radio, infrared, visible, ultraviolet, X-ray, and gamma-ray frequencies as well as the evolving radio-frequency structure of the jet on sub-milliarcsecond scales. Telescopes used currently include the Fermi Gamma-ray Space Telescope, the Very Long Baseline Array (VLBA), the Global mm-VLBI Array, the Rossi X-Ray Timing Explorer (RXTE), the Swift satellite, the Chandra X-ray Observatory, the Hubble Space Telescope, the Spitzer Space Telescope, the XMM-Newton X-ray observatory, Lowell Observatory’s Perkins Telescope and Discovery Channel Telescope, and various other ground- and space-based observatories. Currently, significant effort is being expended on multi-waveband observations that monitor the brightness, polarization, and images of the jets to correlate with the Fermi gamma-ray light curves from 37 blazars and radio galaxies. Marscher and Dr. Svetlana Jorstad are members of the Event Horizon Telescope collaboration that uses a global array of high-precision radio dishes, operating at a wavelength of 1 mm, to image the regions immediately surround the black holes of relatively nearby galactic nuclei, as well as the innermost regions of the jets of more distant quasars.