My primary research interest is the study of relativistic jets. An astronomical jet is a
long, thin stream of material that emanates from the nucleus of the central object, and
deposits its material some distance from the origin. Jets are observed emanating from
many astronomical objects, ranging from newborn stars to super-massive black holes in
galactic nuclei. Jets associated with active galactic nuclei (AGN) are some of the
largest objects in the universe, reaching lengths of over a million light years, and
having bulk flow velocities near the speed of light.
Computer simulations of relativistic jet hydrodynamics have been available for some
years. However, these simulations have a basic limitation. The hydrodynamic simulations
give us the distribution of energy, density and momentum in the simulated jet. Renderings
of these distributions do not resemble the radio flux maps of real jets. This is because
the flow is relativistic. The effects of beaming, time delay, and Doppler boost dominate
the emission. These effects are strongly related to angle of view. A small change in
angle of view can result in a very different radio flux distribution. In addition, the
effects of time-delay are important, as the photon crossing time is longer than the
evolutionary time-scale of the flow. In my work, I attempt relate the emission we observe
to the physical conditions in the jet by an analysis of the radiation transfer
calculation through simulated flows. By determining the physical conditions present when
bright features form in the simulated jet we can begin to understand what conditions lead
to the formation of bright features in real jets.
I have developed a suite of computer programs that use the output of a hydrodynamic
simulation to generate a time-delayed simulated flux map of the simulated jet, at any
angle of view. This software can be used to generate maps of both two-dimensional and
three dimensional simulations. After the maps have been made, we can examine the
physical conditions that lead to the formation of bright features in the jet. This tool
is a new way of analyzing the simulations.
Below are links to 2D images, 3D images, as well as animations of evolutionary sequences of jet formation.