Quasi‐periodic Inward Shock Formations in the System of a Black Hole and an Accretion Disk and Application to Quasi‐periodic Oscillations in Galactic Black Hole Candidates
Bibliographic record
Abstract
We performed 1.5-dimensional general relativistic hydrodynamic simulations with a Kerr metric to construct a model for high-frequency quasi-periodic oscillations (QPOs) in microquasars. The simulations were performed assuming an initial accretion disk without viscosity rotating around a Kerr black hole at sub-Keplerian velocity (sub-Keplerian case), which induces various wave modes everywhere in the disk. We found that quasi-periodic inward shock waves propagate from the accretion disk toward the black hole. The frequency of the shock formation is about the maximum epicyclic frequency in the disk (κ max ), which depends on the rotation of the black hole. In order to understand the mechanism of the shock formation, we also performed a simulation assuming an initial linear perturbation injected at one point in the Keplerian disk (linear perturbation case) and found an oscillation with frequency ~κ at the point where the perturbation injection occurred. To explain the simulation result, we derived an analytic solution for the time evolution of the linear perturbation of physical variables near the point of the perturbation injection and found that the time evolution of the oscillation can be described well. From comparison of the result in the sub-Keplerian case with that of the linear perturbation case, we found that the periodicity of the quasi-periodic shock formation in the sub-Keplerian case is due to a filtering effect by the epicyclic frequency distribution in the disk, which acts on the wave propagation toward the black hole. The only necessary condition for quasi-periodic shock formation is having a nonsteady character for the disks, which can be a source of acoustic waves. The frequency of the shock formation (~κ max ) is on the order of the frequency of the high-frequency QPOs in microquasars and depends on the rotation of the black hole. Hence, we can estimate the spin parameter ( a ) of a black hole candidate (BHC) in a microquasar by comparing the frequency of the high-frequency QPO with κ max . The spin parameters of the BHCs in microquasars are roughly estimated to be a = 0.345 ± 0.345 for GRS 1915+105 and a = 0.895 ± 0.105 for GRO J1655-40.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".