Correlations between triaxial shapes and formation history of dark matter haloes. Issue 1 (11th August 2020)

• Record Type: Journal Article
• Authors: Lau, Erwin T; Hearin, Andrew P; Nagai, Daisuke; Cappelluti, Nico
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 1(2021)
• Page Start: 1029
• Page End: 1037
• Publication Date: 2020-08-11
• Subjects: methods: numerical -- galaxies: clusters: general -- galaxies: groups: general -- dark matter -- large-scale structure of Universe -- cosmology: theory; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3313
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The shape of dark matter (DM) haloes plays a critical role in constraining cosmology with upcoming large-scale structure surveys. In this paper, we study the correlations between the triaxial shapes and formation histories in DM haloes in the MultiDark Planck 2 N -body cosmological simulation. We find that halo ellipticity is strongly correlated with halo properties that serve as proxies of halo formation history, such as halo concentration and the normalized peak-centroid offset. These correlations are nearly independent of the halo density peak height. We present a simple model for the correlation between halo ellipticity and concentration using conditional abundance matching, and provide fitting formulae for the multidimensional distributions of triaxial halo shape as a function of halo peak height. We apply our halo shape model to gauge the effects of halo ellipticity and orientation bias on the excess surface mass density profiles in cluster-sized haloes. Our model should be useful for exploring the impact of triaxial halo shape on cosmological constraints in upcoming weak lensing surveys of galaxy clusters.