Strongly Magnetized Super-Eddington Accretion: How Spin and Accretion Rate Regulate Energy Output and Mass Loss
Tom Man Kwan, Lixin Dai, Cheuk Kwan Kan, Zepei Xing, Tassos Fragos, Matthew Middleton, Tao Ji, Feng Yuan
astro-ph.HE
Submitted: 2026-07-31
Comments: 15 main figures, 4 tables, submitted
License: http://creativecommons.org/licenses/by/4.0/
The gist: Strongly magnetized super-Eddington accretion flows power many important astrophysical systems, but how black hole parameters control their output is unclear.
Terminology
Abstract
Strongly magnetized super-Eddington accretion flows power many important astrophysical systems, but how black hole parameters control their output is unclear. We present 32 general relativistic radiation magnetohydrodynamics simulations of super-Eddington magnetically arrested disks onto stellar-mass black holes, varying mass (M BH= 5, 15, 30,M), spin (a=0,0.9), and accretion rate (acc about 1-2000, Edd). We find that black hole spin and accretion rate jointly regulate wind loss rates and energy output efficiencies, while black hole mass has no effect over the mass range studied here. The BH accretes only 10-40% of the mass supplied to the accretion flow, while the rest is expelled in winds. This accretion fraction decreases with mass supply rate and is lower for high-spin systems. Both spin states produce strong magnetically driven outflows. For a = 0, the wind kinetic, radiative, and electromagnetic efficiencies are modest and show little variation across the full simulated range of accretion rates. For a = 0.9, both wind power and jet power increase super-linearly with acc, with the jet power saturating beyond acc about 100, Edd. Radiation is strongly beamed along the funnel, with inverse beaming factors exceeding 100 for high-spin, high- models viewed face-on. Our results establish that rapid BH spin boosts energy-extraction efficiency, while high accretion rate amplifies total power. We provide scaling relations for luminosities, jet power, accretion ratio, and beaming, offering a framework for interpreting observations of ULXs and other super-Eddington systems.
Sources
- Numerical Simulations of Super-Eddington Accretion Flows
- Exploring the nature of ultra-luminous X-ray sources across stellar population ages using detailed binary evolution calculations
- Optical Counterparts of Ultraluminous X-Ray Sources
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