A solution to the paradox of youth in the Galactic centre

Abstract

The supermassive black hole at the Galactic centre, Sgr A*, is surrounded by an S cluster of young stars. These stars are predominantly B-type stars, but their origin remains uncertain. Unlike massive stars in the Galactic field, which exhibit a binary fraction of about $70\%$, those in the S cluster show a significantly lower fraction. It is key to understand this discrepancy for constraining their formation. We show that the binary deficit arises naturally from dynamical interactions between stellar binaries and Sgr A* in an in situ formation scenario. Using K-amplitude data, we derived an observational binary fraction of $f_{\mathrm{obs}}=0.43\pm 0.09$ for the S-cluster stars. Our dynamical modelling predicts that interactions with Sgr A* cause $18\%$ of the binaries to merge, $20\%$ to be disrupted, and $62\%$ to survive, yielding a theoretical binary fraction of $f_{\mathrm{theo}}=0.38\pm 0.10$. The predicted binary fraction with distance from Sgr A* is also consistent with independent observational constraints. These results show that the decline in binarity towards the Galactic centre is driven by stronger tidal forces, and they support an in situ origin of the S cluster in the same event that produced the Fermi bubbles.

arXiv comment7 pages; Published in A&A; added Zenodo

References in corpus (41)

• Binary interaction dominates the evolution of massive stars
• Monitoring stellar orbits around the Massive Black Hole in the Galactic Center
• Measuring Distance and Properties of the Milky Way's Central Supermassive Black Hole with Stellar Orbits
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• The Eccentric Kozai-Lidov Effect and Its Applications
• A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty
• The First Measurement of Spectral Lines in a Short-Period Star Bound to the Galaxy's Central Black Hole: A Paradox of Youth
• SINFONI in the Galactic Center: young stars and IR flares in the central light month
• An Update on Monitoring Stellar Orbits in the Galactic Center
• Stellar Populations in the Central 0.5 pc of the Galaxy II: The Initial Mass Function
• The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits
• Star formation in a galactic outflow
• Merging Binaries in the Galactic Center: The eccentric Kozai-Lidov mechanism with stellar evolution
• Star Formation Around Super-Massive Black Holes
• Properties of the Remnant Clockwise Disk of Young Stars in the Galactic Center
• Resonant relaxation and the warp of the stellar disc in the Galactic centre
• Binary Encounters With Supermassive Black Holes: Zero-Eccentricity LISA Events
• The Great Escape: Discovery of a nearby 1700 km/s star ejected from the Milky Way by Sgr A*
• 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
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• In situ formation of SgrA* stars via disk fragmentation: parent cloud properties and thermodynamics
• A population of dust-enshrouded objects orbiting the Galactic black hole
• Binary dynamics near a massive black hole
• Relativity and the evolution of the Galactic center S-star orbits
• The Hills Mechanism and the Galactic Center S-stars
• A rapid evolving region in the Galactic Center: Why S-stars thermalize and more massive stars are missing
• Spectroscopic Detection of a Cusp of Late-type Stars around the Central Black Hole in the Milky Way
• Where intermediate-mass black holes could hide in the Galactic Centre: A full parameter study with the S2 orbit
• Ejection of hypervelocity binary stars by a black hole of intermediate mass orbiting Sgr A*
• Evidence of a Decreased Binary Fraction for Massive Stars Within 20 Milliparsecs of the Supermassive Black Hole at the Galactic Center
• A binary system in the S cluster close to the supermassive black hole Sagittarius A*
• Sgr A${}^{\ast }$ envelope explosion and the young stars in the centre of the Milky Way
• Photometric Classification of Stars Around the Milky Way's Central Black Hole: I. Central Parsec
• Reversible time-step adaptation for the integration of few-body systems
• A direct N-body integrator for modelling the chaotic, tidal dynamics of multi-body extrasolar systems: TIDYMESS
• The GWs from the S-stars revolving around the SMBH at Sgr A*
• Discovery of Galactic center ejected star in DESI DR1
• The gas streamer G1-2-3 in the Galactic Center
• Closing the gap: Follow-up observations of peculiar dusty objects close to Sgr A* using ERIS