Modelling black hole accretion through an 𝛼-disc with a resolved interstellar medium in dwarf galaxies

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• Eun-jin Shin (IoA)
• Friday 07 February 2025, 11:30-12:30
• Ryle Seminar Room, KICC + online.

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We perform high-resolution simulations of an isolated dwarf galaxy with a virial mass of 1e10 Msun harbouring a 1e4 Msun intermediate mass black hole (IMBH) embedded in a nuclear star cluster (NSC) at its centre. To model a realistic interstellar medium (ISM), we incorporate IMF -sampled star formation, photo-ionisation feedback, H_II region modelling, photoelectric heating from a spatially varying far-ultraviolet field, and supernova feedback. Our approach employs a sub-grid Shakura-Sunyaev accretion disc model to accurately simulate the evolution of BH mass and spin. Using super-Lagrangian refinement techniques, we resolve spatial scales up to 0.01 pc, capturing the self-gravitating radius of the accretion disc, allowing accurate measurement of mass and angular momentum transfer to the IMBH . The gravitational potential of the NSC captures the ISM , forming a circumnuclear disc (CND), while its torques drive angular momentum loss from parsec to sub-parsec scales, circularising gas onto the 𝛼-accretion disc and fuelling IMBH accretion. We further investigate star formation in the vicinity of the IMBH . In the innermost regions, within 0.2 pc, star formation is highly suppressed. However, at distances of approximately 1 to 7 pc from the centre, the gas remains locally susceptible to fragmentation, leading to the formation of massive, young stars. The feedback from these stars can potentially disrupt the CND entirely and cut off the gas supply to the IMBH . Our study demonstrates the complexity of IMBH accretion once the resolved ISM is taken into account and paves the way for next-generation studies incorporating IMBH -driven feedback processes.

This talk is part of the Galaxies Discussion Group series.

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