## Contact Information

237 Loomis Lab, MC-704

1110 W. Green St.

Urbana, IL 61801

## Research Areas

## Biography

Professor Shapiro has broad research interests that span many areas of theoretical astrophysics and general relativity theory, including the physics of black holes and neutron stars, gravitational collapse, the generation of gravitational waves, and the dynamics of large N-body dynamical systems. His research emphasizes the use of supercomputers to solve long-standing, fundamental problems in numerical relativity and computational astrophysics. Shapiro has worked on the theory of accretion onto compact objects, relativistic stellar dynamics, gravitational collapse, binary black hole and neutron star inspiral and coalescence, the generation of gravitational waves, the formation of black holes, Big-Bang nucleosynthesis and neutrino astrophysics, to name a few topics. Some of his most important simulations include the emitted radiation spectrum from gas accreting onto black holes and neutron stars, the disruption and consumption of stars in star clusters containing a central supermassive black hole, the formation of a supermassive black hole at the center of a galaxy or quasar from the collapse of a relativistic collisionless gas, the head-on collision and merger of two black holes, and the gravitational wavetrain from the late inspiral of coalescing binary neutron stars. He merged the fields of stellar dynamics and numerical relativity, a development which led to the simulation of the catastrophic collapse of an unstable, relativistic cluster to a black hole, the demonstration that toroidal black holes can arise as transients during gravitational collapse, and the possibility that naked singularities might form during the collapse of collisionless matter from reasonable initial conditions, thereby violating cosmic censorship. Long interested in the future detection of gravitational waves by laser interferometers like LIGO and LISA, Shapiro and his group are working on the theory of gravitational wave generation and the identification of promising astrophysical sources.

Professor Shapiro's deep interest in training young scientists has given him a reputation as an inspiring and effective classroom teacher and research advisor. He has created and taught over a dozen courses in physics and astrophysics. The textbook that he coauthored, *Black Holes, White Dwarfs and Neutron Stars: The Physics of Compact Objects* (John Wiley, 1983) is a standard in the field. His research has led him to develop numerous videos of his computer simulations, which offer both great technical insight to experts and qualitative understanding to non-specialists. He leads a vibrant group of graduate students and postdocs working in theoretical astrophysics and general relativity. For over two decades he has trained an expert team of advanced undergraduates doing research in theoretical astrophysics and general relativity by means of supercomputer simulation and visualization. His undergraduate research program is among the most successful in the nation; members of his team are highly sought after by the most select graduate programs in physics, astronomy, computer science, and related areas.

## Research Description

With my group I will pursue research in general relativity and theoretical astrophysics funded by my NSF and NASA grants. Our area of focus will be tackling problems involving general relativity, the generation of gravitational radiation, relativistic hydrodynamics, and relativistic magnetohydrodynamics. A common thread uniting the different theoretical topics is the crucial role of gravitation, especially relativistic gravitation. Compact objects provide the principal forum, and the dynamics of matter in a strong gravitational field is a major theme. Some of the topics for investigation include the inspiral and coalescence of compact binaries (binary black holes, binary neutron stars, binary black hole--neutron stars and binary white dwarf-neutron stars), the generation of gravitational waves from binaries and othe rpromising astrophysical sources and the accompanying electromagnetic signals, gravitational collapse, the stability of rotating, relativistic stars and the evolution and final fate of unstable stars, gamma-ray burst sources, and circumbinary disks around merging supermassive black holes in the cores of galaxies and quasars. Most of these topics represent long-standing, fundamental problems in theoretical physics requiring large-scale computation for solution. Hence the approach involves to a significant degree large-scale computations on parallel machines, as well as analytical modeling. Many of the numerical calculations employ the state-of-the-art computational and visualization resources of the UIUC's National Center for Supercomputing Applications (NCSA), including Blue Waters. They comprise both initial value and evolution computations and treat vacuum spacetimes containing black holes as sell as spacetimes containing realistic matter sources, magnetic fields and both electromagnetic and neutrino radiation. The results have important implications for astronomical observations, including those planned for gravitational wave interferometers, such as the Advanced LIGO/VIRGO network, GEO, KAGRA and eLISA, and for telescopes that will measure transient optical events, such as the LSST.

## Education

A.B in astronomy (1969) Harvard University

M.A. astrophysical sciences (1971) Princeton University

PhD astrophysical sciences (1973) Princeton University

## Additional Campus Affiliations

Research Professor, Physics

## External Links

## Recent Publications

Barausse, E., Berti, E., Hertog, T., Hughes, S. A., Jetzer, P., Pani, P., Sotiriou, T. P., Tamanini, N., Witek, H., Yagi, K., Yunes, N., Abdelsalhin, T., Achucarro, A., van Aelst, K., Afshordi, N., Akcay, S., Annulli, L., Arun, K. G., Ayuso, I., ... Zumalacarregui, M. (2020). Prospects for fundamental physics with LISA. *General Relativity and Gravitation*, *52*(8), [81]. https://doi.org/10.1007/s10714-020-02691-1

Chiang, B. T., Shapiro, S. L., & Shelton, J. (2020). Faint dark matter annihilation signals and the Milky Way's supermassive black hole FAINT DARK MATTER ANNIHILATION SIGNALS and the ... CHIANG, SHAPIRO, and SHELTON. *Physical Review D*, *102*(2), [023030]. https://doi.org/10.1103/PhysRevD.102.023030

Ruiz, M., Tsokaros, A., & Shapiro, S. L. (2020). Magnetohydrodynamic simulations of binary neutron star mergers in general relativity: Effects of magnetic field orientation on jet launching. *Physical Review D*, *101*(6), [064042]. https://doi.org/10.1103/PhysRevD.101.064042

Tsokaros, A., Ruiz, M., Shapiro, S. L., Sun, L., & Uryu, K. (2020). Great Impostors: Extremely Compact, Merging Binary Neutron Stars in the Mass Gap Posing as Binary Black Holes. *Physical review letters*, *124*(7), [071101]. https://doi.org/10.1103/PhysRevLett.124.071101

Tsokaros, A., Ruiz, M., & Shapiro, S. L. (2020). Locating ergostar models in parameter space. *Physical Review D*, *101*(6), [064069]. https://doi.org/10.1103/PhysRevD.101.064069