Theoretical astrophysics uses fundamental laws of physics, ranging from particle physics to gravitational theory, to investigate a wide variety of observable astronomical phenomena.

Professor Cowsik's research interest include astro-particle physics, mainly galactic dynamics of dark matter and itsdetection, especially at the interface of particle physics and cosmology,astrophysics of cosmic- ray, radio, x-ray, gamma-ray and neutrinosources like accreting neutron stars and black holes, supernova remnants,galaxies, active galactic nuclei and gamma ray bursts.

Professor Katz's work involves rapidly varying and high energy processes, building on work on gamma-ray bursts that included the first (1994) prediction of their afterglows. He has recently investigated the implications of an "anti-glitch" in an Anomalous X-ray Pulsar, finding that it is more readily explained in an accretional model than by the popular "magnetar" model. The recent discovery and confirmation of Fast Radio Bursts has revived interest in the problem of coherent emission of high brightness temperature radio radiation. By examining constraints on maximally bright emitters he was able to infer highly relativistic expansion, suggesting a relation to the physics of gamma-ray bursts (even though the radio bursts are not associated with observed gamma-ray bursts). This also led him to investigate possible explanations of "perytons", a mysterious form of terrestrial radio interference found in searches for transient radio sources.

Professor Krawczynski studies the properties of the X-ray and gamma-ray emission from relativistic outflows (jets) from stellar mass and supermassive black holes. The work aims at understanding of how astrophysical black holes grow by accreting matter and how they impact their environment. More recently, Krawczynski evaluated tests of the theory of General Relativity in the strong gravity regime based on X-ray observations. Observations with current and upcoming NASA missions can be used to test General Relativity's No-Hair-Theorem that predicts that astrophysical black holes are described by the Kerr metric.