Imprints of Different Types of Low-angular-momentum Accretion Flow Solutions in General Relativistic Hydrodynamic Simulations
Depending on the astrophysical source and its environment, the accretion flows can exhibit a variety of behaviors and characteristics in accordance with the type of solutions. We study low-angular-momentum accretion flows onto black holes using 2D general relativistic hydrodynamic simulations to fin...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/adf221 |
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| Summary: | Depending on the astrophysical source and its environment, the accretion flows can exhibit a variety of behaviors and characteristics in accordance with the type of solutions. We study low-angular-momentum accretion flows onto black holes using 2D general relativistic hydrodynamic simulations to find imprints of different types of accretion solutions. Such flows, relevant to X-ray binaries and wind-fed low-luminosity active galactic nuclei, often lack sufficient angular momentum to form standard accretion disks. We initialize simulations with semianalytical transonic solutions defined by specific energy ( ${{ \mathcal E }}_{0}$ ) and angular momentum ( λ _0 ), allowing a systematic classification of flow types with: (i) an outer sonic point, (ii) an inner sonic point, and (iii) both, exhibiting shock transitions. Only solutions with two sonic points produce hot, thermally driven bipolar jets/outflows with Lorentz factors up to γ ∼ 2, despite the absence of magnetic fields. Using a general relativistic radiation transfer calculation, we compute broadband spectra and images at X-ray (1 keV) from bremsstrahlung emission. Radiative properties depend strongly on the type of accretion solution. Solutions with inner sonic points produce the brightest and most extended X-ray emission, while outer-point solutions produce compact, fainter signals. These multidimensional models are thus essential for predicting radiative signatures and will enable the development of semianalytical tools for interpreting X-ray binaries and possibly Sgr A* in weak magnetic field regimes. |
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| ISSN: | 1538-4357 |