Constraints on the massconcentration relation of cold dark matter halos with 11 strong gravitational lenses
Abstract
The massconcentration relation of dark matter halos reflects the assembly history of objects in hierarchical structure formation scenarios, and depends on fundamental quantities in cosmology such as the slope of the primordial matter powerspectrum. This relation is unconstrained by observations on subgalactic scales. We derive the first measurement of the massconcentration relation using the image positions and flux ratios from eleven quadrupleimage strong gravitational lenses (quads) in the mass range 10^{6}  10^{10}M_{⊙}, assuming cold dark matter. We model both subhalos and line of sight halos, finitesize background sources, and marginalize over nuisance parameters describing the lens macromodel. We also marginalize over the the logarithmic slope and redshift evolution of the massconcentration relation, using flat priors that encompass the range of theoretical uncertainty in the literature. At z = 0, we constrain the concentration of 10^{8}M_{⊙} halos c=12_{5}^{+6} at 68 % CI, and c=12_{9}^{+15} at 95 % CI. For a 10^{7}M_{⊙} halo, we obtain 68 % (95 %) constraints c=15_{8}^{+9} (c=15_{11}^{+18}), while for 10^{9}M_{⊙} halos c=10_{4}^{+7} (c=10_{7}^{+14}). These results are consistent with the theoretical predictions from massconcentration relations in the literature, and establish strong lensing by galaxies as a powerful probe of halo concentrations on subgalactic scales across cosmological distance.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 February 2020
 DOI:
 10.1093/mnrasl/slz173
 arXiv:
 arXiv:1909.02573
 Bibcode:
 2020MNRAS.492L..12G
 Keywords:

 gravitational lensing: strong;
 cosmology: dark matter;
 galaxies: struc ture;
 methods: statistical;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  Astrophysics of Galaxies
 EPrint:
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