The former companion of the hyper-velocity star S5-HVS1

Abstract

The hyper-velocity star S5-HVS1, ejected 5 Myr ago from the Galactic Center at 1800 km/s, was most likely produced by tidal break-up of a tight binary by the supermassive black hole SgrA*. Taking a Monte Carlo approach, we show that the former companion of S5-HVS1 was likely a main-sequence star between 1.2 and 6 solar masses and was captured into a highly eccentric orbit with pericenter distance in the range 1-10 AU and semimajor axis about $10^3$ AU. We then explore the fate of the captured star. We find that the heat deposited by tidally excited stellar oscillation modes leads to runaway disruption if the pericenter distance is smaller than about 3 AU. Over the past 5 Myr, its angular momentum has been significantly modified by orbital relaxation, which may stochastically drive the pericenter inwards below 3 AU and cause tidal disruption. We find an overall survival probability in the range 5% to 50%, depending on the local relaxation time in the close environment of the captured star, and the initial pericenter at capture. The pericenter distance of the surviving star has migrated to 10-100 AU, making it potentially the most extreme member of the S-star cluster. From the ejection rate of S5-HVS1-like stars, we estimate that there may currently be a few stars in such highly eccentric orbits. They should be detectable (typically Ks < 18.5 mag) by the GRAVITY instrument and by future Extremely Large Telescopes and hence provide an extraordinary probe of the spin of SgrA*.

MNRAS accepted after minor revision

References in corpus (16)

• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• 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
• Stellar remnants in galactic nuclei: mass segregation
• Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities
• Heartbeat Stars, Tidally Excited Oscillations, and Resonance Locking
• Rates of Stellar Tidal Disruption
• Dynamical evolution of the young stars in the Galactic center: N-body simulations of the S-stars
• Illuminating Massive Black Holes With White Dwarfs: Orbital Dynamics and High Energy Transients from Tidal Interactions
• Chaotic Tides in Migrating Gas Giants: Forming Hot and Transient Warm Jupiters via High-Eccentricity Migration
• Tidal Disruptions of Main Sequence Stars -- I. Observable Quantities and their Dependence on Stellar and Black Hole Mass
• Dynamical and evolutionary constraints on the nature and origin of hypervelocity stars
• S62 on a 9.9 yr Orbit around SgrA*
• The impact of mass segregation and star-formation on the rates of gravitational-wave sources from extreme mass ratio inspirals
• SPISEA: A Python-Based Simple Stellar Population Synthesis Code for Star Clusters
• The Hills Mechanism and the Galactic Center S-stars

Cited by in corpus (4)

• Quasi-periodic eruptions from mildly eccentric unstable mass transfer in galactic nuclei
• Mass ratio, the hills mechanism, and the galactic centre S-stars
• The S stars' zone of avoidance in the Galactic center
• A Recent Supermassive Black Hole Binary in the Galactic Center Unveiled by the Hypervelocity Stars