Bing Zhang, professor in the Department of Phyics and Astronomy, will be the featured speaker at an upcoming Astronomy Colloquium. His talk is titled, "GW170817/GRB170817A/AT2017gfo/afterglow: What did the first NS-NS merger event tell us?"

The first NS-NS merger event detected by the humankind, GW170817, was associated with a short GRB 170817A, a "kilonova" AT2017gfo, and a broad-band (from radio to X-rays) afterglow. I will critically review the observational data and various ideas of interpreting this watershed event, and present my understanding of the event regarding the origin of the GRB and its 1.7 seconds delay with respect to the merger, origin of the "kilonova" and the broadband afterglow, as well as the nature of the merger product (black hole vs. a long-lived neutron star) and implications for the poorly constrained neutron star equation of state.