Evolution of eccentric stellar disks around supermassive black holes: the complex disk disruption dynamics and the milliparsec stars

Abstract

We study the 10 Myr evolution of parsec-scale stellar disks with initial masses of $M_{\mathrm{disk}}=1.0$ - $7.5\times 10^4{M}_{\odot }$ and eccentricities $e_{\mathrm{init}}=0.1$-$0.9$ around supermassive black holes (SMBHs). Our disk models are embedded in a spherical background potential and have top-heavy single and binary star initial mass functions (IMF) with slopes of $0.25$-$1.7$. The systems are evolved with the N-body code $\text{BIFROST}$ including post-Newtonian (PN) equations of motion and simplified stellar evolution. All disks are unstable and evolve on Myr timescales towards similar eccentricity distributions peaking at $e_{\star }\sim 0.3$-$0.4$. Models with high $e_{\mathrm{init}}$ also develop a very eccentric $(e_{\star }\gtrsim 0.9)$ stellar population. For higher disk masses $M_{\mathrm{disk}}\gtrsim 3\times 10^4{\mathrm{M}}_{\odot }$, the disk disruption dynamics is more complex than the standard secular eccentric disk instability with opposite precession directions at different disk radii - a precession direction instability. We present an analytical model describing this behavior. A milliparsec population of $N\sim 10$-$100$ stars forms around the SMBH in all models. For low $e_{\mathrm{init}}$ stars migrate inward while for $e_{\mathrm{init}}\gtrsim 0.6$ stars are captured by the Hills mechanism. Without PN, after $6$ Myr the captured stars have a sub-thermal eccentricity distribution. We show that including PN effects prevents this thermalization by suppressing resonant relaxation effects and cannot be ignored. The number of tidally disrupted stars is similar or larger than the number of milliparsec stars. None of the simulated models can simultaneously reproduce the kinematic and stellar population properties of the Milky Way center clockwise disk and the S-cluster.

34 pages, 28 figures, accepted for publication in MNRAS

References in corpus (39)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• An Update on Monitoring Stellar Orbits in the Galactic Center
• Tidal Disruption Events
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• Starbursts near supermassive black holes: young stars in the Galactic Center, and gravitational waves in LISA band
• Very massive stars, pair-instability supernovae and intermediate-mass black holes with the SEVN code
• The structure of the nuclear stellar cluster of the Milky Way
• The Solar Neighborhood XLV. The Stellar Multiplicity Rate of M Dwarfs Within 25 pc
• Simulations of star formation in a gaseous disc around sgr A* - a failed AGN
• Star Formation Around Super-Massive Black Holes
• PARSEC V2.0: Stellar tracks and isochrones of low and intermediate mass stars with rotation
• PeTar: a high-performance N-body code for modeling massive collisional stellar systems
• Twelve years of spectroscopic monitoring in the Galactic Center: the closest look at S-stars near the black hole
• Simulations of the formation of stellar discs in the Galactic centre via cloud-cloud collisions
• Compact object mergers: exploring uncertainties from stellar and binary evolution with SEVN
• Hypervelocity Stars: From the Galactic Center to the Halo
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• On the Formation of Compact Stellar Disks Around Sgr A*
• A numerical study of vector resonant relaxation
• The young stars in the Galactic Center
• Photometric Stellar Variability in the Galactic Center
• Effects of Intermediate Mass Black Holes on Nuclear Star Clusters
• Stellar dynamical evidence against a cold disc origin for stars in the Galactic Centre
• Cluster Core Dynamics at the Galactic Center
• MSTAR -- a fast parallelised algorithmically regularised integrator with minimum spanning tree coordinates
• Steeper stellar cusps in galactic centers from binary disruption
• Relativistic dynamics of stars near a supermassive black hole
• A simple and accurate prescription for the tidal disruption radius of a star and the peak accretion rate in tidal disruption events
• An optimum time-stepping scheme for N-body simulations
• Where intermediate-mass black holes could hide in the Galactic Centre: A full parameter study with the S2 orbit
• FROST: a momentum-conserving CUDA implementation of a hierarchical fourth-order forward symplectic integrator
• BIFROST: simulating compact subsystems in star clusters using a hierarchical fourth-order forward symplectic integrator code
• Evidence of a Decreased Binary Fraction for Massive Stars Within 20 Milliparsecs of the Supermassive Black Hole at the Galactic Center
• The properties of hypervelocity stars and S-stars originating from an eccentric disc around a supermassive black hole
• A numerical study of stellar discs in galactic nuclei
• Mass ratio, the hills mechanism, and the galactic centre S-stars
• In situ formation of the massive stars around SgrA*
• The Orbital Structure and Selection Effects of the Galactic Center S-Star Cluster

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