Matter in the Beam: Weak Lensing, Substructures, and the Temperature of Dark Matter

Abstract

Warm Dark Matter (WDM) models offer an attractive alternative to the current Cold Dark Matter (CDM) cosmological model. We present a novel method to differentiate between WDM and CDM cosmologies, namely using weak lensing; this provides a unique probe as it is sensitive to all the "matter in the beam", not just dark matter haloes and the galaxies that reside in them, but also the diffuse material between haloes. We compare the weak lensing maps of CDM clusters to those in a WDM model corresponding to a thermally produced 0.5 keV dark matter particle. Our analysis clearly shows that the weak lensing magnification, convergence and shear distributions can be used to distinguish between CDM and WDM models. WDM models increase the probability of weak magnifications, with the differences being significant to 5σ, while leaving no significant imprint on the shear distribution. WDM clusters analysed in this work are more homogeneous than CDM ones, and the fractional decrease in the amount of material in haloes is proportional to the average increase in the magnification. This difference arises from matter that would be bound in compact haloes in CDM being smoothly distributed over much larger volumes at lower densities in WDM. Moreover, the signature does not solely lie in the probability distribution function but in the full spatial distribution of the convergence field.

The Present and Future Status of Heavy Neutral Leptons

“…Gravitational lensing (and microlensing) is a promising way to probe the presence of substructures directly (c.f. [715][716][717][718][719][720][721][722][723][724][725][726][727]). The detection of low mass halos within the main lensing halo [see e.g.…”

Sterile Neutrino Dark Matter

“…An alternative way to constraint the matter power spectrum is provided by weak lensing [304][305][306][307][308][309]. However, the power spectra of CDM and WDM models are distinct mostly at high redshifts (as WDM structure formation starts later and then "catches up" with CDM when entering non-linear stage).…”

Influence of ∼7 keV sterile neutrino dark matter on the process of reionization

“…The corresponding values of lepton asymmetry obtained under assumption that such sterile neutrino constitutes the bulk of dark matter in the Universe are then used to produce the power spectra of sterile neutrino dark matter [33][34][35]. The obtained dark matter power spectra and their analogues are then used to investigate various outputs of cosmological structure formation such as subhalo number counts [33,[36][37][38] and subhalo velocity function [36,37,39] in the Local Group, central mass density distributions in nearby haloes and subhaloes [36,37,39,40], mass of Milky Way halo hosting observable number of satellite galaxies [35], high-z galaxy counts [33] and 3D matter power spectra [38,39], 1D matter power spectra probed by Ly-α observations [38], halo mass functions [40], concentration-mass scaling relation for dark matter haloes [40][41][42][43], maximal values of dark matter phase-space density in dwarf spheroidal galaxies [33], shapes and spins of dark matter haloes [40], mass assembly history and infall time of the Fornax dwarf spheroidal galaxy [44], anomalous flux ratios in strong lensed systems [45], weak lensing maps of galaxy clusters [46].…”