The Swansong of Stars The Swansong of Stars Orbiting Massive Black Orbiting Massive Black Holes Holes Clovis Hopman Clovis Hopman Weizmann Institute of Science Weizmann Institute of Science Israel Israel Advisor Advisor : : Tal Tal Alexander Alexander
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The Swansong of Stars Orbiting Massive Black Holes
The Swansong of Stars Orbiting Massive Black Holes. Clovis Hopman Weizmann Institute of Science Israel. Advisor : Tal Alexander. Dissipative stellar processes near Massive Black Holes. Tidally powered stars in the Galactic Center Ultraluminous X-ray sources Gravitational Wave Radiation. - PowerPoint PPT Presentation
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The Swansong of Stars The Swansong of Stars Orbiting Massive Black Orbiting Massive Black
HolesHolesClovis HopmanClovis Hopman
Weizmann Institute of ScienceWeizmann Institute of ScienceIsraelIsrael
AdvisorAdvisor: : Tal Tal AlexanderAlexander
Tidally powered stars in the Galactic Tidally powered stars in the Galactic CenterCenter
Super Eddington luminosities Super Eddington luminosities IBH: engine of ULX?IBH: engine of ULX? IBH can be formed dynamically IBH can be formed dynamically
in cluster in cluster (Portegies Zwart et al., Nature 2004)(Portegies Zwart et al., Nature 2004)
What feeds the IBH??What feeds the IBH??
Clusters contain too little gasClusters contain too little gas Tidal disruption of star gives only Tidal disruption of star gives only
short (~yr) flare short (~yr) flare (Rees, Nature 1988)(Rees, Nature 1988)
Solution: Tidal Capture!
ULX: ULX: IBH fed by a tidally captured IBH fed by a tidally captured
starstar
Circularization possible around IBHCircularization possible around IBH Roche lobe overflow supplies gasRoche lobe overflow supplies gas ULX can switch on after cluster ULX can switch on after cluster
evaporatesevaporates Lifetime and luminosity as observedLifetime and luminosity as observed
CircularizationCircularization
r
max
p
in
p
t
)aN(<~Γ
at<t
a>a
r
:rate cone-lossEmpty
:Scattering vsInspiral
:truncation-Cusp
periapse minimal :Eddington
max0
min,
Hopman, Portegies Zwart & Alexander, ApJL 2004
Captured StarsCaptured Stars
sun5
max 10 mass BH Maximal M~M
Rate independent of relaxation time
Hopman, Portegies Zwart & Alexander, ApJL 2004
Probability = Capture Rate Stellar Lifetime 10 %
Hopman, Portegies Zwart & Alexander, ApJL 2004
Mass Transfer and Mass Transfer and LuminosityLuminosity
Eccentricity of LISA starsEccentricity of LISA stars
Monte Carlo tracks in phase Monte Carlo tracks in phase spacespace
Hopman & Alexander, in prep.
LISA Stars in the Strong Gravity LISA Stars in the Strong Gravity RegimeRegime
Hopman & Alexander, in prep.
Massive Black Holes: Intermediate Mass Black Holes:
Mass segregation: Heavy stars closer Mass segregation: Heavy stars closer to MBH!to MBH!
Rate independent of relaxation timeRate independent of relaxation time Orbits are very eccentricOrbits are very eccentric Probably no signal from IBHsProbably no signal from IBHs
ConclusionsConclusions
Squeezars observable in Galactic Squeezars observable in Galactic CenterCenter
Tidally captured stars around IBHs Tidally captured stars around IBHs may be the engine that powers ULXsmay be the engine that powers ULXs
LISA stars will be highly eccentricLISA stars will be highly eccentric