A variable ADAF disk model for X-ray binary systems
Fuente:
arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866910048640303104 |
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| author | Xu, Chun |
| author_facet | Xu, Chun |
| contents | We propose a variable ADAF disk model for X-ray binary systems. In this model, the accretion flow consists of an outer thin disk and an inner optically thick advection-dominated accretion flow (ADAF) torus. The size of the turbulent ADAF is variable. A complete cycle of ADAF contraction, transition to a thin disk, and subsequent re-expansion corresponds to the rapid rise, peak, and decay phases observed in the X-ray outbursts of black hole binaries. This cycle also tracks the canonical evolution through the low-hard, high-soft, and back to the low-hard state in the hardness-intensity diagram. The model unifies the presence of near-ISCO Fe emission lines with the truncated disk paradigm, as observed in the black hole system GX 339-4. It explains the 35-day period in the neutron star system Her X-1 more effectively through variable ADAF sizes than through a precessing disk. This variable ADAF framework may be extended to explain similar phenomena in active galactic nuclei. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_10311 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | A variable ADAF disk model for X-ray binary systems Xu, Chun High Energy Astrophysical Phenomena We propose a variable ADAF disk model for X-ray binary systems. In this model, the accretion flow consists of an outer thin disk and an inner optically thick advection-dominated accretion flow (ADAF) torus. The size of the turbulent ADAF is variable. A complete cycle of ADAF contraction, transition to a thin disk, and subsequent re-expansion corresponds to the rapid rise, peak, and decay phases observed in the X-ray outbursts of black hole binaries. This cycle also tracks the canonical evolution through the low-hard, high-soft, and back to the low-hard state in the hardness-intensity diagram. The model unifies the presence of near-ISCO Fe emission lines with the truncated disk paradigm, as observed in the black hole system GX 339-4. It explains the 35-day period in the neutron star system Her X-1 more effectively through variable ADAF sizes than through a precessing disk. This variable ADAF framework may be extended to explain similar phenomena in active galactic nuclei. |
| title | A variable ADAF disk model for X-ray binary systems |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2603.10311 |