Halo concentration strengthens dark matter constraints in galaxy-galaxy strong lensing analyses
arXiv:2109.00018 · doi:10.1093/mnras/stab3527
Abstract
A defining prediction of the cold dark matter (CDM) cosmological model is the existence of a very large population of low-mass haloes. This population is absent in models in which the dark matter particle is warm (WDM). These alternatives can, in principle, be distinguished observationally because halos along the line-of-sight can perturb galaxy-galaxy strong gravitational lenses. Furthermore, the WDM particle mass could be deduced because the cut-off in their halo mass function depends on the mass of the particle. We systematically explore the detectability of low-mass haloes in WDM models by simulating and fitting mock lensed images. Contrary to previous studies, we find that halos are harder to detect when they are either behind or in front of the lens. Furthermore, we find that the perturbing effect of haloes increases with their concentration: detectable haloes are systematically high-concentration haloes, and accounting for the scatter in the mass-concentration relation boosts the expected number of detections by as much as an order of magnitude. Haloes have lower concentration for lower particle masses and this further suppresses the number of detectable haloes beyond the reduction arising from the lower halo abundances alone. Taking these effects into account can make lensing constraints on the value of the mass function cut-off at least an order of magnitude more stringent than previously appreciated.
MNRAS submitted. Comments welcome
References in corpus (10)
- The NumPy array: a structure for efficient numerical computation
- Dark matter and cosmic structure
- Bayesian Strong Gravitational-Lens Modeling on Adaptive Grids: Objective Detection of Mass Substructure in Galaxies
- Inference of the Cold Dark Matter substructure mass function at z=0.2 using strong gravitational lenses
- How well can cold-dark-matter substructures account for the observed radio flux-ratio anomalies?
- Joint constraints on thermal relic dark matter from strong gravitational lensing, the Lyman- forest, and Milky Way satellites
- Constraints on the properties of warm dark matter using the satellite galaxies of the Milky Way
- PyAutoLens: Open-Source Strong Gravitational Lensing
- Inferring the concentration of dark matter subhalos perturbing strongly lensed images
- Exploiting flux ratio anomalies to probe warm dark matter in future large scale surveys