Matter of Life & Death: The impact of environmental conditions on the origins of stars and supermassive black holes

TL;DR

This paper investigates how environmental factors like turbulence, rotation, magnetic fields, and radiation influence the formation of supermassive black hole seeds and the properties of the interstellar medium in high-redshift galaxies through simulations and modeling.

Contribution

It presents new 3D hydrodynamical simulations and an extended photodissociation region code to analyze the impact of feedback mechanisms on gas fragmentation and thermodynamics in early universe conditions.

Findings

Turbulence and rotation affect primordial gas fragmentation.

Strong UV radiation keeps gas hot, limiting fragmentation.

Feedback processes significantly influence the chemical and thermal state of the ISM.

Abstract

Observational evidence suggests that some very large supermassive black holes (SMBHs) already existed less than 1 Gyr after the Big Bang. Explaining the formation and growth of the 'seeds' of these SMBHs is quite challenging. We explore the formation of such seeds in the direct collapse scenario. Using 3D hydrodynamical simulations, we investigate the impact of turbulence and rotation on the fragmentation behavior of collapsing primordial gas in the presence of a strong UV radiation background, which keeps the gas hot. Additionally, we explore different ways in which the collapsing gas may be able to stay hot, and thus limit fragmentation. Using a one-zone model, we examine the interplay between magnetic fields, turbulence, and a UV radiation background. Feedback processes from stars and black holes shape the interstellar medium (ISM) out of which new generations of luminous objects form. To understand the properties of these objects, e.g. the stellar initial mass function, it is vital to have knowledge of the chemical and thermodynamical properties of the feedback-regulated ISM. To better understand the chemo-thermal state and fragmentation behavior of gas in high-redshift galaxies, we updated, improved, and extended a photodissociation region code. Our computational code, PDR-Zz, is described in detail. Using this code, a grid of models is run, covering a sizable range in physical properties. This allows us to systematically explore the overall impact of various feedback effects, both radiative and chemical, on the chemical and thermal balance of the gas in different physical regimes.