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Compact objects, such as black holes, neutron stars, and white dwarfs, often exist in pairs which eventually merge. These systems are strong sources of gravitational waves, and their nature and the environment in which they reside has a profound effect on possible associated electromagnetic signatures.

Professor Fong’s group looks for EM counterparts to GW events with observing programs in Hawaii, Chile, and Arizona. They are particularly interested in studying short gamma-ray bursts (GRBs) whose progenitors are likely neutron star mergers with other neutron stars or black holes.

Professor Margutti’s group makes observations of GW counterparts, studying the non-thermal emission associated with the formation and launching of relativistic jets by the compact merger in X-rays and radio.

Professor Faucher-Giguère’s group uses theoretical predictions and numerical simulations about galaxy formation and supermassive black holes to make predictions about the nature and number of supermassive black hole binaries in the Cosmos.

Professor Larson’s group is interested in low-frequency gravitational wave sources that will be observable by LISA. This includes massive black hole binaries, which LISA will observe to the cosmological horizon; ultra-compact white dwarf binaries, many of which can already be seen with Earth-based telescopes; and stellar mass objects falling into massive black holes. These are all strong GW sources, and all can have electromagnetic counterparts.

Professor Tchekhovskoy uses supercomputer magneto-hydrodynamic simulations to study the end of black hole mergers, in particular the post-merger remnant disk evolution, its outflows and jets, which will have profound influence on the observable electromagnetic signatures.

Professor Kalogera’s group works in the LIGO Scientific Collaboration to develop techniques for gravitational-wave analysis. One result of their work are sky localizations, inferred from our gravitational-wave measurements, that are then used to hunt down multi-messenger counterparts. Combining these observations with gravitational-wave data, we can learn more about processes such as neutron-star binary mergers.

Professor Larson’s group works in the LISA Consortium to better understand the stellar graveyard of the Milky Way, using population synthesis techniques to better understand the distribution and observability of white dwarfs throughout the galaxy. The white dwarf binaries are the most numerous gravitational wave source in the sky, and multi-messenger observations will provide an unprecedented probe of close binary star evolution.