Feedback from intermediate-mass black holes on dwarf galaxy morphology at z = 2

¹ Departamento de Astronomía, Facultad Ciencias Físicas y Matemáticas, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160-C, Concepción, Chile
² Dipartimento di Fisica, Sapienza Universitá di Roma, Piazzale Aldo Moro 5, 00185 Rome, Italy
³ Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile

^⋆ Corresponding author; bida@udec.cl

Received: 30 September 2024
Accepted: 5 December 2024

Abstract

Aims. This study aims to elucidate the role of intermediate-mass black holes (IMBHs) in the development of galactic morphology. We examine how the evolution of IMBHs is influenced by various factors, including seed masses, seed times, and feedback mechanisms. Additionally, we investigate potential correlations between galactic morphology and the final properties of central dwarf galaxies, such as gas fraction, taking into account the constraints of black hole growth history and active galactic nucleus (AGN) feedback. This exploration is particularly valuable to the characterization of the typical environments associated with IMBHs in dwarf galaxies.

Methods. We utilized a series of high-resolution zoom-in cosmological simulations to analyze the emergent morphology of central dwarf galaxies within dark matter halos of similar mass, specifically log M_vir/M_⊙ ∼ 10 ± 0.05, at redshift z ∼ 2. All simulations are initialized with the same conditions while employing different black hole seeding methods and feedback schemes. This approach enables us to investigate how varying black hole evolutionary pathways affect the fundamental parameters of central dwarf galaxies. Our simulations consider galaxies embedded in both high- and low-spin host halos, utilizing various black hole seed masses, seed formation times, and AGN wind velocities.

Results. We find that AGN feedback, particularly wind strength, critically influences gas fractions, star formation, and galaxy structure. Galaxies with strong feedback exhibit lower stellar masses, flatter morphologies, and intermediate rotational support (κ_rot = 0.3 − 0.6). Their prominent central structures and low Sersic indices (n < 2) highlight the limits of applying low-redshift diagnostics such as Gini-M20 at high redshift. Synthetic JWST observations suggest pixelation effects can overestimate galaxy sizes, emphasizing the nuanced relationship between IMBH evolution and dwarf galaxy formation.