Possible smoking-gun evidence for initial mass segregation in re-virialized post-gas expulsion globular clusters

Haghi, Hosein, Zonoozi, Akram Hasani, Kroupa, Pavel, Banerjee, Sambaran and Baumgardt, Holger (2015) Possible smoking-gun evidence for initial mass segregation in re-virialized post-gas expulsion globular clusters. Monthly Notices of the Royal Astronomical Society, 454 4: 3872-3885. doi:10.1093/mnras/stv2207

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Author Haghi, Hosein
Zonoozi, Akram Hasani
Kroupa, Pavel
Banerjee, Sambaran
Baumgardt, Holger
Title Possible smoking-gun evidence for initial mass segregation in re-virialized post-gas expulsion globular clusters
Journal name Monthly Notices of the Royal Astronomical Society   Check publisher's open access policy
ISSN 1365-2966
0035-8711
Publication date 2015-12-21
Year available 2015
Sub-type Article (original research)
DOI 10.1093/mnras/stv2207
Open Access Status File (Publisher version)
Volume 454
Issue 4
Start page 3872
End page 3885
Total pages 14
Place of publication Oxford, United Kingdom
Publisher Oxford University Press
Language eng
Abstract We perform a series of direct N-body calculations to investigate the effect of residual gas expulsion from the gas-embedded progenitors of present-day globular clusters (GCs) on the stellar mass function (MF). Our models start either tidally filling or underfilling, and either with or without primordial mass segregation. We cover 100 Myr of the evolution of modelled clusters and show that the expulsion of residual gas from initially mass-segregated clusters leads to a significantly shallower slope of the stellar MF in the low- (m ≤ 0.50 M⊙) and intermediate-mass (≃ 0.50–0.85 M⊙) regime. Therefore, the imprint of residual gas expulsion and primordial mass segregation might be visible in the present-day MF. We find that the strength of the external tidal field, as an essential parameter, influences the degree of flattening, such that a primordially mass-segregated tidally filling cluster with rh/rt ≥ 0.1 shows a strongly depleted MF in the intermediate stellar mass range. Therefore, the shape of the present-day stellar MF in this mass range probes the birth place of clusters in the Galactic environment. We furthermore find that this flattening agrees with the observed correlation between the concentration of a cluster and its MF slope, as found by de Marchi et al.. We show that if the expansion through the residual gas expulsion in primordial mass segregated clusters is the reason for this correlation then GCs most probably formed in strongly fluctuating local tidal fields in the early proto-Milky Way potential, supporting the recent conclusion by Marks & Kroupa.
Keyword Galaxies: star clusters: general
Methods: numerical -Galaxy: formation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2016 Collection
 
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