| Name: Abishek Balakrishnan |
| Affiliation: Indian Institute of Astrophysics |
| Conference ID: ASI2026_596 |
| Title: Formation of supermassive black holes |
| Abstract Type: Poster |
| Abstract Category: Galaxies and Cosmology |
| Author(s) and Co-Author(s) with Affiliation: Abishek Balakrishnan(Indian Institute of Astrophysics, Bangalore - 560034, India), Prof. Arun Mangalam(Indian Institute of Astrophysics, Bangalore - 560034, India) |
| Abstract: Supermassive Black Holes (SMBHs) are believed to be at the center of all massive galaxies, as inferred
from observations of Quasars over the years, which places a strong constraint of ∼ 10^9M⊙
at z ∼ 6 on these objects. However, how smaller progenitor seeds for these SMBHs are formed at
high redshifts remains an open question. In this work, we investigate the formation of these seeds
through the runaway collapse of a dense stellar system. We start with the formation of the dense
stellar system itself through a spherical collapse model, which provides a rotationally supported structure
that fragments and allows star formation. The evolution of this system is then followed as it contracts
and undergoes core collapse, wherein a small region within the core of
the system becomes so dense that the general relativistic instability kicks in and the whole region
collapses dynamically to give a massive black hole. The system’s evolution is studied by doing a
Fokker-Planck analysis in a general relativistic framework, along with solving the Einstein field equations for a
non-static spherically symmetric metric describing the system. We provide an estimate for the mass
of the seed black hole obtained and the total time for the collapse (and hence a formation redshift)
for a set of different initial conditions that helps compare with observations. For a cluster core
mass of M_c = 10^3M⊙, we obtain a seed M_seed = 800M⊙, while for a M_c = 10^4M⊙, a seed of M_seed = 5000M⊙ was formed,
both within z ≥ 14. Furthermore, we demonstrate how this seed black hole grows through stellar
capture and gas accretion using a mass-spin co-evolution model for the black hole. Our results
compare well with the observations, including the latest high-redshift JWST objects. |
