The Population and Evolution of Dual AGNs at Radio Wavelengths: Predictions for the ngVLA

Astronomers predict that most massive galaxies in the Universe will have merged with at least one other massive galaxy during their lifetime. As supermassive black holes inhabit the centers of massive galaxies, scientists therefore expect to find that a fraction of galaxies will have a pair of black holes at their centers. The orbit of these black holes will slowly decay, and the two black holes will interact with their surroundings and shine brightly. This research team will develop an innovative model of how these dual black holes shine at radio wavelengths. A web interface developed as part of this project will allow anyone to access a database of predicted radio bright black holes and plan observations to search for them. The investigators will also develop a workshop on oral communications skills for graduate students at Georgia Tech. Results of the workshops and lessons-learned will be published. This research team will develop an innovative model of dAGN activity at radio wavelengths and is built on four pillars: (1) the catalog of massive galaxy mergers predicted by the IllustrisTNG cosmological simulations, (2) calculations of the orbital evolution at kpc-scales due to gaseous and stellar dynamical friction of a secondary SMBH in a post-merger galaxy, (3) the relativistic jet power found from simulations of moving black holes through magnetized gas, and (4) first-principles modeling of the radio synchrotron spectrum from the jet cores. By considering different SMBH orbits in each IllustrisTNG merger, the model will generate catalogs of kpc-scale dAGNs as a function of redshift, with each system associated with a specific evolution of the dAGN radio luminosity and spectrum. A web interface developed as part of this project will allow access to the model database and provide actionable predictions on the expected radio source properties from ngVLA surveys of post-merger galaxies. 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.