Bound mass of Dehnen models with a centrally peaked star formation efficiency
Shukirgaliyev B. Otebay A. Sobolenko M. Ishchenko M. Borodina O. Panamarev T. Myrzakul S. Kalambay M. Naurzbayeva A. Abdikamalov E. Polyachenko E. Banerjee S. Berczik P. Spurzem R. Just A.
1 October 2021EDP Sciences
Astronomy and Astrophysics
2021#654
Context. Understanding the formation of bound star clusters with a low star formation efficiency (SFE) is important for improving our knowledge of the star-formation history of galaxies. In N-body models of star-cluster evolution after gas expulsion, the Plummer model with an outer power law density profile has been used in a broad range of studies. Aims. Here, we study the impact of the density profile slopes on the survivability of the low-SFE star clusters after instantaneous gas expulsion. We compare cases when a stellar cluster exhibits a Plummer profile to those with Dehnen profiles, including cuspy ones of different slopes at the time of formation. Methods. We determined the corresponding density profile of the residual gas for a given global SFE, assuming that our model clusters formed with a constant efficiency per free-fall time and, hence, with a shallower density profile for the gas than that of the stars. We performed direct N-body simulations of evolution of clusters initially in virial equilibrium within the gas potential following gas removal. Results. We find that the violent relaxation lasts no longer than 20 Myr, independently of the density profile power law slopes. Dehnen model clusters survive after violent relaxation with significantly lower SFEs when the global SFE measured within the Jacobi radius or within a half-mass radius. Dehnen γ = 0 model clusters show a similar final bound fraction with the Plummer model clusters if the global SFE is measured within ten scale radii. The final bound fraction increases with the γ values for a given global SFE. Conclusions. We conclude that Dehnen clusters better resist the consequences of the violent relaxation that follows the instantaneous gas expulsion, as compared to the Plummer clusters. Therefore, the shallower the outer density slope of the low-SFE clusters, the better their prospects for survival after gas expulsion. Among the Dehnen clusters, we find that the steeper the inner slope, the higher the bound mass fraction that is retained, following the violent relaxation for a given global SFE.
Galaxies: star clusters: general , Methods: numerical , Open clusters and associations: general , Stars: kinematics and dynamics
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Energetic Cosmos Laboratory, Nazarbayev University, 53 Kabanbay Batyr ave., Nur-sultan, 010000, Kazakhstan
Fesenkov Astrophysical Institute, 23 Observatory str., Almaty, 050020, Kazakhstan
Al-Farabi Kazakh National University, 71 Al-Farabi ave., Almaty, 050040, Kazakhstan
Main Astronomical Observatory, National Academy of Sciences of Ukraine, 27 Akademika Zabolotnoho St., Kyiv, 03143, Ukraine
Institute of Astronomy, Russian Academy of Sciences (INASAN), 48 Pyatnitskaya str., Moscow, 119017, Russian Federation
Rudolf Peierls Center for Theoretical Physics, University of Oxford, Parks Road, Oxford, OX1 3PU, United Kingdom
Ratbay Myrzakulov Eurasian International Centre for Theoretical Physics, Nur-Sultan, 010009, Kazakhstan
Center for Theoretical Physics, Eurasian National University, Nur-Sultan, 010008, Kazakhstan
Physics Department, Nazarbayev University, 53 Kabanbay Batyr ave., Nur-sultan, 010000, Kazakhstan
Helmholtz-Institut für Strahlen-und Kernphysik, Nussallee 14-16, Bonn, 53115, Germany
Argelander-Institut für Astronomie, Auf dem Hügel 71, Bonn, 53121, Germany
National Astronomical Observatories, Key Laboratory of Computational Astrophysics, Chinese Academy of Sciences, 20A Datun Rd., Chaoyang District, Beijing, 100101, China
Astronomisches Rechen-Institut Am Zentrum für Astronomie der, Universität Heidelberg, Mönchhofstrasse 12-14, Heidelberg, 69120, Germany
Kavli Institute for Astronomy and Astrophysics at Peking University, 5 Yiheyuan Rd., Haidian District, Beijing, 100871, China
Energetic Cosmos Laboratory
Fesenkov Astrophysical Institute
Al-Farabi Kazakh National University
Main Astronomical Observatory
Institute of Astronomy
Rudolf Peierls Center for Theoretical Physics
Ratbay Myrzakulov Eurasian International Centre for Theoretical Physics
Center for Theoretical Physics
Physics Department
Helmholtz-Institut für Strahlen-und Kernphysik
Argelander-Institut für Astronomie
National Astronomical Observatories
Astronomisches Rechen-Institut Am Zentrum für Astronomie der
Kavli Institute for Astronomy and Astrophysics at Peking University
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