Eccentric Disks from Gaseous Rings around Equal-Mass, Circular Binaries
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arXiv
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2026
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| author | Betancourt, Leonardo MacFadyen, Andrew Zrake, Jonathan |
| author_facet | Betancourt, Leonardo MacFadyen, Andrew Zrake, Jonathan |
| contents | We perform high-resolution, grid-based hydrodynamics simulations of gaseous rings viscously spreading into disks around equal-mass, circular binaries. We find that all systems suppress accretion onto the binary when the gas is relatively cold. Circumbinary rings (CBRs) display weak variability above the binary orbital frequency $Ω_b$ and a dominant spectral peak at $\sim0.1Ω_b$ (half the fiducial lump frequency of $\sim0.2Ω_b$). The evolution of CBR eccentricity depends strongly on both the initial ring radius and gas temperature, with smaller, colder rings exhibiting higher eccentricity up to $e \simeq 0.7$. Cold, compact rings develop nearly radius-independent eccentricity profiles, maintaining large $e$ out to several times the initial gas semimajor axis. We find that eccentricity growth favors a stream impact mechanism, in which gas torqued by the binary at pericenter passage exerts a perturbative force on the cavity wall. We consider inefficiently-accreting, intermediate-mass ($\sim10^4 M_\odot$) black hole binaries as sources of quasi-periodic eruptions when rejected streams shock the cavity wall and radiate in the UV or soft X-ray. We discuss the implications of eccentric disks evolved from CBRs for quasar light curves and asymmetric, time-variable double-peaked line emission from disks in galactic nuclei. If binaries drive asymmetry in accretion disk line profiles, our study suggests that the progenitor CBR must have been very compact. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2601_00741 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Eccentric Disks from Gaseous Rings around Equal-Mass, Circular Binaries Betancourt, Leonardo MacFadyen, Andrew Zrake, Jonathan High Energy Astrophysical Phenomena Astrophysics of Galaxies We perform high-resolution, grid-based hydrodynamics simulations of gaseous rings viscously spreading into disks around equal-mass, circular binaries. We find that all systems suppress accretion onto the binary when the gas is relatively cold. Circumbinary rings (CBRs) display weak variability above the binary orbital frequency $Ω_b$ and a dominant spectral peak at $\sim0.1Ω_b$ (half the fiducial lump frequency of $\sim0.2Ω_b$). The evolution of CBR eccentricity depends strongly on both the initial ring radius and gas temperature, with smaller, colder rings exhibiting higher eccentricity up to $e \simeq 0.7$. Cold, compact rings develop nearly radius-independent eccentricity profiles, maintaining large $e$ out to several times the initial gas semimajor axis. We find that eccentricity growth favors a stream impact mechanism, in which gas torqued by the binary at pericenter passage exerts a perturbative force on the cavity wall. We consider inefficiently-accreting, intermediate-mass ($\sim10^4 M_\odot$) black hole binaries as sources of quasi-periodic eruptions when rejected streams shock the cavity wall and radiate in the UV or soft X-ray. We discuss the implications of eccentric disks evolved from CBRs for quasar light curves and asymmetric, time-variable double-peaked line emission from disks in galactic nuclei. If binaries drive asymmetry in accretion disk line profiles, our study suggests that the progenitor CBR must have been very compact. |
| title | Eccentric Disks from Gaseous Rings around Equal-Mass, Circular Binaries |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2601.00741 |