The Colloquium takes place every Wednesday at 11:15 AM - Warsaw Copernicus Astronomical Centre online by means of Zoom platform. The Colloquium is given in English and chaired by dr Stanisław Bajtlik (bajtlik@camk.edu.pl). People from outside of the Copernicus Center are very welcome to participate. For technical detailes please contact Dr. Stanislaw Bajtlik.
Marina Ishchenko (Academy of Sciences, Ukraine)
Context. To date, two main mechanisms have been proposed for the formation and growth of nuclear star clusters (NSCs) in galaxies. The first suggests in situ star formation from gas that has migrated to the central regions from the galaxy’s outskirts, while the second involves the accretion of stars from disrupted globular clusters (GCs) onto the galactic centre. However, the relative importance of these mechanisms in the evolution of NSCs across different galaxy morphologies remains an open question. Aims. To investigate the accretion of GC stars on early cosmological timescales through detailed N-body simulations of theoretical GC models, in order to assess the role of this mechanism in Milky Way-like galaxies. Methods. For the dynamical modelling, we use the updated parallel N-body code φ-GPU including stellar evolution. We prepared three sets of GC models with different half-mass radii (rhm), each consisting of 50 full N-body GC models, and integrated these models in an external, time-variable Milky Way-like potential taken from the cosmological database IllustrisTNG-100. The simulations cover the time interval from -10 Gyr to -5 Gyr, enabling us to assess the rate of early stellar accretion onto the proto-NSC. Results. GC models with average orbital eccentricities of 0.4–0.5 and orbits oriented perpendicular to the galactic disc contribute most significantly to the mass of the proto-NSC formation. Accretion is especially efficient during the first Gyr and in compact GC models with rhm = 1 pc. In all sets, the dominant accreted stellar population consists of low-mass stars (≈0.33 M⊙). However, the accreted mass alone is insufficient to fully account for the current mass of the NSC. Conclusions. Based on our extended set of numerical simulations, we obtain the lower limit of mass contribution (≈ 2%) to the NSC from disrupted GCs. We conclude that the GC stellar accretion channel alone may not be sufficient to ensure the present day MW galaxy NSC mass budget
Journal Club takes place on Mondays at 11:15 AM in the Seminar Room. The presentation is given in English and is chaired by Journal Club Coordinators. Anyone interested in giving a Journal Club talk is encouraged to contact the email: journalclub(@camk.edu.pl).
Agata Różańska (NCAC, Warsaw)
based on a collection of articles
