Scatterings on a sphere

The environment close to supermassive black holes (SMBHs) has extreme stellar densities that can reach up to 10^7 Msun/pc^3. An example is the SMBH in our galaxy, which features a density cusp composed of old stars, compact remnant and even young massive stars. Among these, binaries are expected to be common. Binaries can efficiently interact dynamically with other stars, undergoing close encounters with the compact remnants of the cusp. We investigated the outcome of such Keplerian 3-body encounters by means of high-accuracy simulations performed with the new state-of-art code TSUNAMI. Three-body encounters can ionize the binaries so that their member are scattered into highly eccentric orbits about the SMBH. Via this scenario, we can explain the origin of the S-stars, the eccentric stars observed orbiting around the SMBH in our galaxy. In addition, binaries that survive the encounters become more eccentric. This effect can be significant for compact binaries that can coalesce via gravitational wave emission.

Alessandro Trani
first floor meeting room, KIAA
Fri, 2018-12-14 12:00 to 13:00