In my work I focus on making concrete theoretical predictions for how accretion flows and jets in black hole systems appear to the Event Horizon Telescope (EHT), a global Very-Long-Baseline-Interferometry (VLBI) array. I am also in the core development team of the Model fitting and parameter estimation framework THEMIS (access restricted), which is a Bayesian MCMC-based scheme embedded in a very powerful, general, extensible and modular framework that can compare various theoretical predictions directly to Event Horizon Telescope data.Collaborators:
Models for the Event Horizon Telescope with Prof. Jonathan McKinney I am studying the physics of black hole accretion disks using the grmhd code HARM as well as the effects of polarized radiative transfer. Polarization measurements of the innermost regions in our galactic center Sag A* and the nearby giant-elliptical galaxy M87 with the Event Horizon Telescope may provide key data to distinguish between competing accretion disk models.Collaborators:
A significant part of my work consists of modeling strong gravitational wave sources, which have been detected directly by the ground-based interferometer advanced LIGO. There is now good reason to belief that such detection will become routine over the next 1-2 years. In the longterm signals from supermassive black hole binaries will be detected by Pulsar Timing Arrays, and (future) space-based missions (LISA). One of the many great things about gravitational waves is that they are generated only in the most violent events in the universe but once emitted they pass through everything essentially without any interaction and are therefore excellent, clean probes of strong-field gravity.
Accretion onto black holes is by far the most efficient process to convert mass into outgoing radiation. Accreting supermassive black holes (eventhough "only" of roughly solar system size) can outshine their entire host galaxy. Many theoretical ideas have emerged over the last 4 decades and is met by an increasing amount of observational data across the EM spectrum. In my work I contribute to the challenge of finding the connection between some theoretical ideas to what is observed in our universe.
For this purpose it is necessary to solve the set of magnetohydrodynamic equations in the framework of General Relativity. In order to capture the full, non-linear and highly dynamic behavior, large scale, numerical simulations are required.
Vasileios Paschalidis, Milton Ruiz, Stuart L. Shapiro, Zachariah B. Etienne, Harald P. Pfeiffer
Image credit: IL REU team: Sean E. Connelly, Abid Khan, Lingyi Kong, Brian R. Taylor, Stuart L. Shapiro