Hyper velocity stars and the restricted parabolic 3-body problem

Shiho Kobayashi, Re'em Sari, Elena M. Rossi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Motivated by detections of hypervelocity stars that may originate from the Galactic Cen- Ter, we revist the problem of a binary disruption by a passage near a much more massive point mass. The six order of magnitude mass ratio between the Galactic Center black hole and the binary stars allows us to formulate the problem in the restricted parabolic three-body approximation. In this framework, results can be simply rescaled in terms of binary masses, its initial separation and binary-to-black hole mass ratio. Consequently, an advantage over the full three-body calculation is that a much smaller set of simula- Tions is needed to explore the relevant parameter space. Contrary to previous claims, we show that, upon binary disruption, the lighter star does not remain preferentially bound to the black hole. In fact, it is ejected exactly in 50% of the cases. Nonetheless, lighter objects have higher ejection velocities, since the energy distribution is independent of mass. Focusing on the planar case, we provide the probability distributions for disruption of circular binaries and for the ejection energy. We show that even binaries that pene- Trate deeply into the tidal sphere of the black hole are not doomed to disruption, but survive in 20% of the cases. Nor do these deep encounters produce the highest ejection energies, which are instead obtained for binaries arriving to 0.1 - 0.5 of the tidal radius in a prograde orbit. Interestingly, such deep-reaching binaries separate widely after pen- etrating the tidal radius, but always approach each other again on their way out from the black hole. Finally, our analytic method allows us to account for a finite size of the stars and recast the ejection energy in terms of a minimal possible separation. We find that, for a given minimal separation, the ejection energy is relatively insensitive to the initial binary separation (see Sari, Kobayashi and Rossi 2010, ApJ 708, 605 for the full discussion).

Original languageAmerican English
Title of host publication12th Marcel Grossmann Meeting on Recent Dev. in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories - Proc. of the MG 2009 Meeting on General Relativity
Pages993-995
Number of pages3
StatePublished - 2012
Event12th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, MG 2009 - Paris, France
Duration: 12 Jul 200918 Jul 2009

Publication series

Name12th Marcel Grossmann Meeting on Recent Dev. in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories - Proc. of the MG 2009 Meeting on General Relativity

Conference

Conference12th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics and Relativistic Field Theories, MG 2009
Country/TerritoryFrance
CityParis
Period12/07/0918/07/09

Keywords

  • Binaries
  • Center
  • Galaxy
  • Halo
  • Kinematics and dynamics
  • Stellar content

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