Simulationbased marginal likelihood for cluster strong lensing cosmology
Abstract
Comparisons between observed and predicted strong lensing properties of galaxy clusters have been routinely used to claim either tension or consistency with Λ cold dark matter cosmology. However, standard approaches to such cosmological tests are unable to quantify the preference for one cosmology over another. We advocate approximating the relevant Bayes factor using a marginal likelihood that is based on the following summary statistic: the posterior probability distribution function for the parameters of the scaling relation between Einstein radii and cluster mass, α and β. We demonstrate, for the first time, a method of estimating the marginal likelihood using the Xray selected z > 0.5 Massive Cluster Survey clusters as a case in point and employing both Nbody and hydrodynamic simulations of clusters. We investigate the uncertainty in this estimate and consequential ability to compare competing cosmologies, which arises from incomplete descriptions of baryonic processes, discrepancies in cluster selection criteria, redshift distribution and dynamical state. The relation between triaxial cluster masses at various overdensities provides a promising alternative to the strong lensing test.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 January 2018
 DOI:
 10.1093/mnras/stx2262
 arXiv:
 arXiv:1507.05617
 Bibcode:
 2018MNRAS.473.1736K
 Keywords:

 gravitational lensing: strong;
 methods: numerical;
 methods: statistical;
 galaxies: clusters: general;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 Astrophysics  Instrumentation and Methods for Astrophysics;
 Physics  Data Analysis;
 Statistics and Probability;
 Statistics  Applications
 EPrint:
 15 pages, 6 figures, 1 table, accepted to MNRAS