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Stellar black hole formation and dynamics: identikit of gravitational wave sources.

Mapelli M., Spera M., Bressan A.
  Lunedì 26/09   15:00 - 19:00   Edificio Psicologia 2 - Aula 2E   III - Astrofisica
The maximum mass of stellar black holes (BHs) in the nearby Universe was long thought to be less than $\sim 20$ solar masses ($M\odot$). Dynamical mass measurements of BHs in X-ray binaries support this idea. However, the LIGO interferometers recently witnessed the coalescence of two BHs with a mass of $\sim 29$ and $36M\odot$, respectively. What physical processes can explain the formation of such massive BH binary? In my talk, I discuss the influence of stellar winds on the mass spectrum of BHs. I show that massive BHs $(>25M\odot$) are expected to form if the metallicity of the progenitor star is sufficiently low $(<0.3Z\odot)$. Moreover, BH binaries can originate either from the evolution of primordial binaries or from dynamical mechanisms ($e.g.$ exchanges, runaway collisions, Kozai resonances,..). I discuss the impact of different formation channels of BH binaries on the merger rate.