Kavli Affiliate: Mark Vogelsberger
| First 5 Authors: Qiaorong S. Yu, Qiaorong S. Yu, , ,
| Summary:
In this study, we define the novel splashback depth $mathcalD$ and width
$mathcalW$ to examine how the splashback features of dark matter haloes are
affected by the physical properties of haloes themselves. We use the largest
simulation run in the hydrodynamic MillenniumTNG project. By stacking haloes in
bins of halo mass, redshift, mass-dependent properties such as peak height and
concentration, and halo formation history, we measure the shape of the
logarithmic slope of the density profile of dark matter haloes. Our results
show that the splashback depth has a strong dependence on the halo mass which
follows a power law $mathcalDproptoleft(log_10Mright)^2.8$.
Properties with strong correlation with halo mass demonstrate similar
dependence. The splashback width has the strongest dependence on halo peak
height and follows a power law $mathcalWproptonu^-0.87$. We provide the
fitting functions of the splashback depth and width in terms of halo mass,
redshift, peak height, concentrations and halo formation time. The depth and
width are therefore considered to be a long term memory tracker of haloes since
they depend more on accumulative physical properties, e.g., halo mass, peak
height and halo formation time. They are shaped primarily by the halo’s
assembly history, which exerts a stronger influence on the inner density
profile than short-term dynamical processes. In contrast, the splashback
features have little dependence on the short term factors such as halo mass
accretion rate and most recent major merger time. The splashback depth and
width can therefore be used to complement information gained from quantities
like the point of steepest slope or truncation radius to characterise the
halo’s history and inner structure.
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