Multifrequency General Relativistic Radiation Magnetohydrodynamic Simulations of Thin Disks

Journal Article · 05 December 2023 · The Astrophysical Journal

DOI: https://doi.org/10.3847/1538-4357/ad096b · OSTI ID:2274886

Fragile, P. Chris  ^[1]; Anninos, Peter ^[2]; Roth, Nathaniel  ^[2]; Mishra, Bhupendra ^[3]

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1. College of Charleston, Charleston, SC (United States); University of California Santa Barbara, CA (United States). Kavli Institute for Theoretical Physics
2. Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
3. Harish-Chandra Research Institute, Jhusi (India)

We present a set of six general relativistic, multifrequency, radiation magnetohydrodynamic simulations of thin accretion disks with different target mass accretion rates around black holes with spins ranging from nonrotating to rapidly spinning. The simulations use the M₁ closure scheme with 12 independent frequency (or energy) bins ranging logarithmically from 5 × 10−³ keV to 5 × 10³ keV. The multifrequency capability allows us to generate crude spectra and energy-dependent light curves directly from the simulations without a need for special postprocessing. While we generally find roughly thermal spectra with peaks around 1–4 keV, our high-spin cases showed harder-than-expected tails for the soft or thermally dominant state. This leads to radiative efficiencies that are up to five times higher than expected for a Novikov–Thorne disk at the same spin. We attribute these high efficiencies to the high-energy, coronal emission. These coronae mostly occupy the effectively optically thin regions near the inner edges of the disks and also cover or sandwich the inner ∼15GM/c² of the disks.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 2274886
• Report Number(s): LLNL--JRNL-854570; {1082749,"Journal ID: ISSN 0004-637X"}
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 1 Vol. 959; ISSN 0004-637X
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English