Age and mass segregation of multiple stellar populations in galactic nuclei and their observational signatures

Hagai B. Perets, Alessandra Mastrobuono-Battisti

Research output: Contribution to journalArticlepeer-review


Nuclear stellar clusters (NSCs) are known to exist around massive black holes in galactic nuclei. They are thought to have formed through in situ star formation following gas inflow to the nucleus of the galaxy and/or through the infall of multiple stellar clusters. Here we study the latter, and explore the composite structure of the NSC and its relation to the various stellar populations originating from its progenitor infalling clusters. We use N-body simulations of cluster infalls and show that this scenario may produce observational signatures in the form of age segregation: the distribution of the stellar properties (e.g., stellar age and/or metallicity) in the NSCs reflects the infall history of the different clusters. The stellar populations of clusters, infalling at different times (dynamical ages), are differentially segregated in the NSC and are not fully mixed even after a few gigayears of evolution. Moreover, the radial properties of stellar populations in the progenitor cluster are mapped to their radial distribution in the final NSC, potentially leading to efficient mass segregation in NSCs, even those where relaxation times are longer than a Hubble time. Finally, the overall structures of the stellar populations present non-spherical configurations and show significant cluster to cluster population differences.

Original languageEnglish
Article numberL44
JournalAstrophysical Journal Letters
Issue number2
StatePublished - 1 Apr 2014


  • Galaxy: center
  • Galaxy: structure
  • globular clusters: general
  • stars: black holes
  • stars: kinematics and dynamics
  • stars: luminosity function, mass function

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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