How do supermassive black holes (SMBH) grow? We know that most galaxies host them, but how you make a black hole that is millions to billions of times the mass of the Sun is an open question in cosmology, deeply related to how large scale structure forms in the Universe. SMBH can host extremely energetic accretion discs, thereby forming active galactic nuclei (AGN) that play a crucial role in distributing material throughout the Universe by launching huge, energetic jets that blow gas out of the host galaxy. This mechanism profoundly affects the rate of star formation. However, we are ignorant of exactly how these jets work.
This Project will use the varying brightness of AGN jets that are pointed towards us—objects known as blazars—to better understand SMBH and the AGN they power. By observing a large sample of them with millimetre-wave (mm) light, we will detect pairs of orbiting SMBH, known as SMBH binaries. The merging of these binaries is thought to be one channel for growing black holes, but convincing observational evidence for them is scant. We expect to increase the number of SMBH binary candidates from a handful to ~30, followed by ~100 within six years after this project ends. These data will provide an exciting window into the growth of SMBH. Furthermore, the ~9,000 blazars in our sample will be used to reveal the physical origins of the mysterious, high energy processes in the heart of AGN jets.
Our data will come from cosmology observatories that make wide-field measurements of the mm sky, allowing us to observe an unprecedented number of blazars. The mm light we use is perfect for our needs since it originates at just right distance from the SMBH to probe the physics of the jets and to search for SMBH binaries. The data we produce will be made publicly available to enable further studies of these fascinating engines of galaxy formation, and our results will be disseminated through journal articles, scientific talks and public outreach events.
