Hubble-Lema\^itre fragmentation and the path to equilibrium of merger-driven cluster formation
| Autor: | Estelle Moraux, Christophe Becker, C. M. Boily, Thomas Maschberger, Julien Dorval |
|---|---|
| Přispěvatelé: | Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
numerical -stars
Stellar population Stellar mass Milky Way kinematics and dynamics -globular clusters general -open clusters and associations Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences methods Gravitational field Stellar dynamics 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Adiabatic process 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Physics 010308 nuclear & particles physics Astronomy Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Stars Space and Planetary Science [SDU]Sciences of the Universe [physics] Stellar mass loss Astrophysics::Earth and Planetary Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2016, 459 (2), pp.1213-1232. ⟨10.1093/mnras/stw714⟩ |
| ISSN: | 0035-8711 1365-2966 |
| Popis: | This paper discusses a new method to generate self-coherent initial conditions for young substructured stellar cluster. The expansion of a uniform system allows stellar sub-structures (clumps) to grow from fragmentation modes by adiabatic cooling. We treat the system mass elements as stars, chosen according to a Salpeter mass function, and the time-evolution is performed with a collisional N-body integrator. This procedure allows to create a fully-coherent relation between the clumps' spatial distribution and the underlying velocity field. The cooling is driven by the gravitational field, as in a cosmological Hubble-Lema\^itre flow. The fragmented configuration has a `fractal'-like geometry but with a self-grown velocity field and mass profile. We compare the characteristics of the stellar population in clumps with that obtained from hydrodynamical simulations and find a remarkable correspondence between the two in terms of the stellar content and the degree of spatial mass-segregation. In the fragmented configuration, the IMF power index is ~0.3 lower in clumps in comparison to the field stellar population, in agreement with observations in the Milky Way. We follow in time the dynamical evolution of fully fragmented and sub-virial configurations, and find a soft collapse, leading rapidly to equilibrium (timescale of 1 Myr for a ~ 10^4 Msun system). The low-concentration equilibrium implies that the dynamical evolution including massive stars is less likely to induce direct collisions and the formation of exotic objects. Low-mass stars already ejected from merging clumps are depleted in the end-result stellar clusters, which harbour a top-heavy stellar mass function. Comment: 22 pages, accepted for publication in MNRAS |
| Databáze: | OpenAIRE |
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