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Markos Georganopoulos

Markos Georganopoulos
Contact Information

Title

Associate Professor

Education

Ph.D. Astronomy – Boston University 1999
M.S. Astronomy – Boston University 1991
B.A. Physics – Aristotle University of Thessaloniki 1989

Previous Experience

Dr. Georganopoulos was previously a National Research Council Fellow at NASA/Goddard (2002-2004) and a postdoctoral researcher at the Max Planck Institut für Kernpysik in Heidelberg (1999-2002).

Professional Interests

My research interests focus on understanding the physics and the broader role of relativistic outflows or jets, mainly in active galaxies, but also in  galactic microquasars and  gamma ray bursts (GRBs). Relativistic jets are invariably connected to accretion onto  black holes. The kinetic power can reach levels  comparable to that of the accretion luminosity, and their relativistically beamed  synchrotron and inverse Compton (IC)  emission can extend up to TeV energies, indicating extremely efficient particle acceleration.

In my work I develop theoretical and numerical models to simulate the  broad-band synchrotron and inverse Compton emission of relativistic flows.  In an effort to explain the X-ray emission of the large-scale quasar jets by Chandra, NASA’s X-ray orbiting observatory, I identified, together with D. Kazanas of NASA/Goddard, a new mode of inverse Compton emission, expected to be prominent in decelerating relativistic jets. Together with D. Kazanas and F. Stecker of NASA/Goddard and E. Perlman of FIT, we have devised a method for understanding if the quasar jets are composed of normal ,e-p matter or from a electron-positron plasma. Our method has been recently applied by us and others to show for the first time that an electron positron composition is very unlikely. I am also developing a theoretical ‘toolbox’ in support of the Fermi gamma-ray NASA mission to understand the innermost, spatially  unresolved  jet formation zone very close to the supermassive quasar black hole.  Recently, I have developed, together collaborators from Goddard, FIT and Oxford , a new, parameter-free method for measuring with Fermi the infrared extragalactic background light, a cosmologically important quantity.

Selected Publications

‘A novel method for measuring the extragalactic background light: Fermi application to the lobes of Fornax A’ , Georganopoulos et al. 2008, ApJ , 686, L5

‘Bulk Comptonization of the Cosmic Microwave Background by Extragalactic Jets as a Probe of Their Matter Content’, Georganopoulos, M., Kazanas, D. Perlman, E. S., Stecker, F. W. 2005, ApJ, 625, 656

‘Relativistic and Slowing Down: The Flow in the Hot Spots of Powerful Radio Galaxies and Quasars,’ Georganopoulos, M. & Kazanas, D. 2003, ApJ, 589, L5

‘Decelerating Flows in TeV Blazars: A Resolution to the BL Lacertae-FR I Unification Problem’ Georganopoulos, M. & Kazanas, D. 2003, ApJ, 594, L27

‘External Compton emission from relativistic jets in Galactic black hole candidates and ultraluminous X-ray sources’, Georganopoulos, M., Aharonian, F. A., Kirk, J. G.,  2002,  A&A 388,  L25

Fornax A, a nearby radio galaxy as seen by the Very Large Array (color) at radio frequencies and by WMAP (contours), NASA's cosmology probe at microwaves.We have recently shown that observations of Fornax A with Fermi, NASA's new Gamma-ray telescope will finally answer the question of how much starlight has been produced during the lifetime of our Universe. Fermi observations are underway.

Fornax A, a nearby radio galaxy as seen by the Very Large Array (color) at radio frequencies and by WMAP (contours), NASA’s cosmology probe at microwaves.
We have recently shown that observations of Fornax A with Fermi, NASA’s new Gamma-ray telescope will finally answer the question of how much starlight has been produced during the lifetime of our Universe. Fermi observations are underway.