Constraints on warm dark matter from weak lensing in anomalous quadruple lenses

TL;DR

This study uses weak lensing effects in quadruple lens systems to constrain warm dark matter particle mass, finding m_WDM >= 1.3 keV, consistent with other cosmological observations, and disfavoring certain WDM models.

Contribution

It provides new constraints on warm dark matter particle mass using weak lensing anomalies in quadruple lens systems, supported by high-resolution simulations.

Findings

WDM particle mass m_WDM >= 1.3 keV at 95% CL

WDM with k_{fs} <= 27 h/Mpc is disfavored as major cosmological component

Results align with constraints from Lyman-alpha forests and high-redshift galaxy counts

Abstract

We investigate the weak lensing effect by line-of-sight structures with a surface mass density of <~10^8 solar mass/arcsec^2 in QSO-galaxy quadruple lens systems. Using high-resolution N-body simulations in warm dark matter (WDM) models and observed four quadruple lenses that show anomalies in the flux ratios, we obtain constraints on the mass of thermal WDM, m_WDM>= 1.3keV(95%CL) assuming that the density of the primary lens is described by a singular isothermal ellipsoid (SIE). The obtained constraint is consistent with those from Lyman-$\alpha$ forests and the number counts of high-redshift galaxies at z>4. Our results show that WDM with a free-streaming comoving wavenumber k_{fs} <= 27 h/Mpc is disfavored as the major component of cosmological density at redshifts 0.5 <~ z <~ 4 provided that the SIE models describe the gravitational potentials of the primary lenses correctly.