Collaborative Research: Time Domain Studies of Supermassive Black Holes

This project seeks to address how supermassive black holes (SMBH) form in the early universe and how they create relativistic jets. The investigators will study two families of SMBHs that are very rare to determine the number of binary SMBHs. They will determine whether the recently discovered gravitational wave background is due to these objects.

One early result from the James Webb Space Telescope is that there are far more binary supermassive black holes in the early universe than expected. The existence of so many binary supermassive black holes poses challenges to cosmology. The PIs will use the 40 m telescope at the Owens Valley Radio Observatory and the Very Long Baseline Array to study the structure of these objects.

The PIs will combine the radio results with optical, infrared, X-ray, Gamma-ray, and gravitational wave observations. The work will be carried out by five graduate students, so this will be important of their career development. In addition, the PIs have started an outreach program, in which they will be studying the jets in these objects, with schools that work with students from disadvantaged backgrounds.

The radio jets from SMBHs will be studied in great detail through their varying radio brightness and structure on the scale of light years. One rare class the PIs will study is SMBH Binaries (SMBHBs). About 1 in 100 radio jets is a SMBHB.

The PIs have detected two convincing SMBHB candidates through their light curves. Their focused search should at least double the number of strong candidates. Each strong candidate is of great importance to multi-messenger astrophysics, since the SMBHBs produce gravitational waves that will in future be detectable by pulsar timing arrays.

They will also study high-luminosity compact symmetric objects (CSOs). The brightest CSOs die out after ~5000-years, whereas most radio jets last up to tens of millions of years, suggesting that a different fueling mechanism drives the brightest CSOs. Astronomers think this is the capture of single stars by the SMBH in a tidal disruption event (TDE).

The PI's will test whether these powerful CSOs really do die out at ~5000-years. By studying these two rare classes, each of which probes details of the central engines in a unique way, they will gain crucial insights into the jet formation and launching mechanism as well as into the SMBHs themselves. Most importantly - if the initial results on CSOs are confirmed in this study, then the smallest CSOs will evolve on timescales of a few years.

This will make possible the direct testing of the general relativistic magnetohydrodynamic theory and simulations of relativistic jets.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.