The population of dark matter subhaloes: mass functions and average mass-loss rates

By Carlo Giocoli, G. Tormen, F. V. D. Bosch, D. Astronomia, U. Padova, M. F. Astronomy, Heidelberg. 2007

145 citations recorded by the source corpus.

Using a cosmological N-body simulation and a sample of resimulated cluster-like haloes, we study the mass-loss rates of dark matter subhaloes, and interpret the mass function of subhaloes at redshift zero in terms of the evolution of the mass function of systems accreted by the main halo progenitor (hereafter called the 'unevolved subhalo mass function'). When expressed in terms of the ratio between the mass of the subhalo at the time of accretion, m v , and the present day host mass, M 0 , the unevolved subhalo mass function is found to be universal, in that it is independent of the mass of the host halo. However, the subhalo mass function at redshift zero (hereafter called the 'evolved subhalo mass function') clearly depends on M 0 , in that more massive host haloes host more subhaloes. In order to relate the unevolved and evolved subhalo mass functions, we measure the subhalo mass-loss rate as a function of host mass and redshift. We find that the average, specific mass-loss rate of dark matter subhaloes depends mainly on redshift, with only a very weak dependence on the instantaneous ratio between the mass of the subhalo, m sb , and that of the host halo at that time M v . In fact, to good approximation, subhalo masses 'decay' exponentially, with a decay time that is proportional to the instantaneous dynamical time of the host halo. Combined with the fact that more massive haloes assemble later, these results suggest a pleasingly simple picture for the evolution and mass dependence of the evolved subhalo mass function. Less massive host haloes accrete their subhaloes earlier, which are thus subjected to mass-loss for a longer time. In addition, their subhaloes are typically accreted by denser hosts, which causes an additional boost of the mass-loss rate. To test the self-consistency of this picture, we use semi-analytical merger trees constructed using the extended Press-Schechter formalism, and evolve the subhalo populations using the average mass-loss rates obtained from our simulations. The resulting subhalo mass functions are found to be in good agreement with the simulations. Our model can be applied to semi-analytical methods of galaxy formation, to accurately follow the time evolution of subhalo masses.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/54d5adc2f4349883e66fcdf7e4c350e240c350ee

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Citations in the corpus

Structure finding in cosmological simulations: the state of affairs (2013, background): “…of halo finders: one can use the tracking results to adjust the halo catalogues and remove spurious identification and/or recover missing objects (Springel et al. 2001b; Gill et al. 2004a; Tormen et al. 2004; Giocoli et al. 2008, 2010; Tweed et al. 2009; Behroozi et al. 2013a; Benson et al. 2012).”
Ahf: AMIGA'S HALO FINDER (2009, background): “…found before (e.g. Ghigna et al. 2000; Helmi et al. 2002; De Lucia et al. 2004; Gao et al. 2004; van den Bosch et al. 2005; Diemand et al. 2007; Giocoli et al. 2008; Springel et al. 2008) that the subhalo mass function can be described with a functional form Nsub(> M) ∝ M −α, with α = 0.7 . .…”
Dark Matter Substructure in Numerical Simulations: A Tale of Discreteness Noise, Runaway Instabilities, and Artificial Disruption (2018, background): “…has become more and more confident that the N-body simulations make reliable predictions regarding the abundance and demographics of dark matter substructure (e.g., Ghigna et al. 1998; Klypin et al. 1999a; Diemand et al. 2004a; Gao et al. 2004; Kravtsov et al. 2004; Giocoli et al. 2008a, 2010).”
Disruption of Dark Matter Substructure: Fact or Fiction? (2017, background): “…large cosmological simulations routinely resolve an entire hierarchy of substructure, with haloes hosting subhaloes, which themselves host sub-subhaloes, etc. (e.g., Ghigna et al. 1998; Tormen et al. 1998; Diemand et al. 2004a; Gao et al. 2004; Kravtsov et al. 2004; Giocoli et al. 2008a, 2010).”
There's no place like home? Statistics of Milky Way-mass dark matter haloes (2009, methodology): “As shown by several authors (e.g., Gao et al. 2004; Giocoli et al. 2008; Angulo et al. 2009), the abundance of subhalos with a given fraction of their host’s mass varies systematically, with more massive hosts having more subhalos.”