The colloquium is being canceled due to risk of inclement weather. The speaker has agreed to reschedule and visit us in the near future.

Standing Out from The Crowd: Finding Supermassive Black-hole Binaries in Gravity & Light
Stephen Taylor (Vanderbilt University)

The Universe is thrumming with gravitational waves. June 2023 brought the first evidence for an all-sky background of nanohertz-frequency gravitational waves, discovered by collaborations including the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and groups in Europe, Australia, India, and China. This was an endeavor decades in the making, requiring painstakingly precise timing observations of scores of millisecond pulsars across the Milky Way using flagship radio telescopes. While the results from separate groups are consistent with one another—and the leading interpretation of a cosmic population of supermassive black-hole binaries as the source—the observations provoke many new questions. Do the results imply a population of binaries more massive than expected? What are the observational milestones as the first resolvable massive black-hole binary signals come into focus? Can we link these signals to host galaxies and leverage electromagnetic counterparts to do multi-messenger astronomy with massive black holes? In this talk, I will chart the path to discovery, reflect on what we have learned during our year+ since our announcement, and explore the exciting opportunities ahead—including the role of next-generation instruments in expanding our pulsar network to explore the low-frequency gravitational-wave and supermassive binary black-hole landscape.

Please join us for the SED Director’s Seminar. Hosted by the Astroparticle Physics Laboratory, Code 661!