On the Accuracy of Timedelay Cosmography in the Frontier Fields Cluster MACS J1149.5+2223 with Supernova Refsdal
Abstract
We study possible systematic effects on the values of the cosmological parameters measured through strong lensing analyses of the Hubble Frontier Field galaxy cluster MACS J1149.5+2223. We use the observed positions of a large set of spectroscopically selected multiple images, including those of supernova "Refsdal" with their published time delays. Starting from our reference model in a flat ΛCDM cosmology, published in Grillo et al. (2018), we confirm the relevance of the longest measurable time delay, between SX and S1, and an approximately linear relation between its value and that of H_{0}. We perform true blind tests by considering a range of time delays around its original estimate of 345 ± 10 days, as an accurate measurement of this time delay is still not known at the time of analysis and writing. We investigate separately the impact of a constant sheet of mass at the cluster redshift, of a powerlaw profile for the mass density of the cluster main halo and of some scatter in the cluster member scaling relations. Remarkably, we find that these systematic effects do not introduce a significant bias on the inferred values of H_{0} and Ω_{m} and that the statistical uncertainties dominate the total error budget: a 3% uncertainty on the time delay of image SX translates into approximately 6% and 40% (including both statistical and systematic 1σ) uncertainties for H_{0} and Ω_{m}, respectively. Furthermore, our model accurately reproduces the extended surface brightness distribution of the supernova host. We also present the interesting possibility of measuring the value of the equationofstate parameter w of the dark energy density, currently with a 30% uncertainty.
 Publication:

The Astrophysical Journal
 Pub Date:
 July 2020
 DOI:
 10.3847/15384357/ab9a4c
 arXiv:
 arXiv:2001.02232
 Bibcode:
 2020ApJ...898...87G
 Keywords:

 Strong gravitational lensing;
 Cosmological parameters;
 Dark matter;
 Dark energy;
 Galaxy clusters;
 Hubble constant;
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 339;
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 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 10 pages, 8 figures, 1 table