Clumpy Outflows from Super-Eddington Accreting Black Holes I: Radiation Hydrodynamics Simulations and Observational Implications

TL;DR

This paper uses high-resolution radiation-hydrodynamics simulations to model clumpy outflows from super-Eddington black hole accretion, providing insights into their structure, dynamics, and observational signatures consistent with recent X-ray observations.

Contribution

It presents the first detailed simulation-based analysis of clumpy outflows from super-Eddington accretion flows, linking theoretical models with observational data.

Findings

Clumpy outflows extend across wide radial and angular ranges.

Clump properties include size ~10 rg, velocity 0.05-0.2 c, and optical depth 1-10.

Simulated clump characteristics align with recent X-ray observations.

Abstract

Recent advances in X-ray spectroscopic observation have enabled researchers to reveal distinct clumpy structures in the super-Eddington outflows from the supermassive black hole in PDS 456 (XRISM Collaboration 2025), initiating detailed investigation of fine-scale structures in accretion-driven outflows. In this study, we conduct high-resolution, two-dimensional radiation-hydrodynamics simulations with time-varying and anisotropic initial and boundary conditions to reproduce outflows launched from super-Eddington accretion flows and analyze their statistical properties. The resulting clumpy outflows extend across a wide range of radial distances and polar angles, exhibiting typical properties such as a size of ~10 rg (where rg is the gravitational radius), a velocity of ~0.05-0.2 c (where c is the speed of light), and about five clumps along the line of sight. Although the velocities are slightly smaller, these characteristics reasonably resemble those obtained from the XRISM observation. The gas density of the clumps is on the order of 10^{-13}-10^{-12} g cm^{-3}, and their optical depth for electron scattering is approximately 1-10. The clumpy winds accelerated by radiation force are considered to originate from the region within <~300 rg.