Astronomy Lunch Seminar Series

Abstract: GRMHD simulations of accretion disks provide the bedrock for interpreting many modern observations of black hole accretion, especially direct radio imaging, which relies on large simulations libraries. Unfortunately, even with the most careful choices for initial conditions, simulations can retain an imprint of those biasing choices even at late times. Reconciling this intrinsic bias, which may not well represent actual astrophysical behavior, remains an outstanding and, I will argue, under-addressed theoretical problem. By making new, but not radically different choices in these initial conditions, I will demonstrate accretion disk simulations we have performed that represent a cost-saving approach to reaching long evolution timescales, and which demonstrate significant differences in comparison to the traditional approach. I will explain the fundamentals of our approach, a suite of new simulations of hot accretion flows in full 3D-GRMHD, and how these simulations may shift our interpretation of observations. In this library, we also explore the effect of high horizon-scale magnetization, but less than the Magnetically Arrested Disk (MAD) state.