Mass Segregation Phenomena using the Hamiltonian Mean Field Model

TL;DR

This study demonstrates that mass segregation phenomena naturally arise in the Hamiltonian Mean Field model due to long-range interactions, occurring during violent relaxation and quasi-stationary states, independent of system dimensionality.

Contribution

It reveals that mass segregation is a dynamical feature caused by long-range forces in the HMF model, occurring in one-dimensional systems and during different relaxation phases.

Findings

Mass segregation appears during violent relaxation.

MSP persists in quasi-stationary states.

Mass distribution is independent of system dimensionality.

Abstract

Mass segregation problem is thought to be entangled with the dynamical evolution of young stellar clusters \cite{olczak}. This is a common sense in the astrophysical community. In this work, the Hamiltonian Mean Field (HMF) model with different masses is studied. A mass segregation phenomenon (MSP) arises from this study as a dynamical feature. The MSP in the HMF model is a consequence of the Landau damping (LD) and it appears in systems that the interactions belongs to a long range regime. Actually HMF is a toy model known to show up the main characteristics of astrophysical systems due to the mean field character of the potential and for different masses, as stellar and galaxies clusters, also exhibits MSP. It is in this sense that computational simulations focusing in what happens over the mass distribution in the phase space are performed for this system. What happens through the violent relaxation period and what stands for the quasi-stationary states (QSS) of this dynamics is analyzed. The results obtained support the fact that MSP is observed already in the violent relaxation time and is maintained during the QSS. Some structures in the mass distribution function are observed. As a result of this study the mass distribution is determined by the system dynamics and is independent of the dimensionality of the system. MSP occurs in a one dimensional system as a result of the long range forces that acts in the system. In this approach MSP emerges as a dynamical feature. We also show that for HMF with different masses, the dynamical time scale is $N$.