2017/10/31 by Angelo Ricarte, Priyamvada Natarajan · 1 citation
Physics and Astronomy · #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stx2851
Accepted by MNRAS October 30th, 2017. 18 pages, 12 figures, 2 tables
arxiv created 2017/10/31 · arxiv updated 2017/12/27
We develop a semi-analytic model to explore different prescriptions of supermassive black hole (SMBH) fuelling. This model utilises a merger-triggered burst mode in concert with two possible implementations of a long-lived steady mode for assembling the mass of the black hole in a galactic nucleus. We improve modelling of the galaxy-halo connection in order to more realistically determine the evolution of a halo's velocity dispersion. We use four model variants to explore a suite of observables: the M-sigma relation, mass functions of both the overall and broad-line quasar population, and luminosity functions as a function of redshift. We find that "downsizing" is a natural consequence of our improved velocity dispersion mappings, and that high-mass SMBHs assemble earlier than low-mass SMBHs. The burst mode of fuelling is sufficient to explain the assembly of SMBHs to z=2, but an additional steady mode is required to both assemble low-mass SMBHs and reproduce the low-redshift luminosity function. We discuss in detail the trade-offs in matching various observables and the interconnected modelling components that govern them. As a result, we demonstrate the utility as well as the limitations of these semi-analytic techniques.