SURFS: Riding the waves with Synthetic UniveRses For Surveys

Pascal J. Elahi; Charlotte Welker; Chris Power; Claudia del P. Lagos; Aaron Robotham; Rodrigo Cañas; Rhys Poulton

doi:10.1093/mnras/sty061

paper

SURFS: Riding the waves with Synthetic UniveRses For Surveys

arXiv:1712.01988 · doi:10.1093/mnras/sty061

Abstract

We present the Synthetic UniveRses For Surveys ({\sc surfs}) simulations, a set of N-body/Hydro simulations of the concordance $Λ$ Cold Dark Matter (\LCDM) cosmology. These simulations use Planck cosmology, contain up to 10 billion particles and sample scales & halo masses down to $1$ kpc & $1 0^{8} M_{⊙}$ . We identify and track haloes from $z = 24$ to today using a state-of-the-art 6D halo finder and merger tree builder. We demonstrate that certain properties of halo merger trees are numerically converged for haloes composed of $≳ 100$ particles. Haloes smoothly grow in mass, $V_{max}$ , with the mass history characterised by $lo g M (a) \propto exp [- (a / β)^{α}]$ where $a$ is the scale factor, $α (M) \approx 0.8$ \& $β (M) \approx 0.024$ , with these parameters decreasing with decreasing halo mass. Subhaloes follow power-law cumulative mass and velocity functions, i.e. $n (> f) \propto f^{- α}$ with $α_{M} = 0.83 \pm 0.01$ and $α_{V_{max}} = 2.13 \pm 0.03$ for mass \& velocity respectively, independent of redshift, as seen in previous studies. The halo-to-halo scatter in amplitude is $0.9$ ~dex. The number of subhaloes in a halo weakly correlates with a halo's concentration $c$ \& spin $λ$ :haloes of high $c$ \& low $λ$ have $60%$ more subhaloes than similar mass haloes of low $c$ \& high $λ$ . High cadence tracking shows subhaloes are dynamic residents, with $25%$ leaving their host halo momentarily, becoming a backsplash subhalo, and another $20%$ changing hosts entirely, in agreement with previous studies. In general, subhaloes have elliptical orbits, $e \approx 0.6$ , with periods of $2. 3_{- 1.7}^{+ 2.1}$ ~Gyrs. Subhaloes lose most of their mass at pericentric passage with mass loss rates of $\sim 40%$ ~Gyr $^{- 1}$ . These catalogues will be made publicly available.

22 pages, 20 figures, accepted for publication in MNRAS

SURFS: Riding the waves with Synthetic UniveRses For Surveys

Abstract

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