Jul 5 – 10, 2021
Europe/Rome timezone

A tale of two double quasars: Hubble constant tension or biases?

Jul 5, 2021, 5:15 PM
Talk in the parallel session Cosmography with Gravitational Lensing Cosmography with Gravitational Lensing


Luis J. Goicoechea (Universidad de Cantabria)


For a flat $\Lambda$CDM (standard) cosmology, a small sample of gravitationally lensed quasars with measured time delays has recently provided a value of the Hubble constant $H_0$ in agreement with data from SNe, but in tension with the Planck flat $\Lambda$CDM result. Identifying biases in some methods may solve this tension, avoiding hasty rejection of the standard cosmological model. As a case study, we use two double quasars of the GLENDAMA sample (SBS 0909+532 and SDSS J1339+1310) to discuss the $H_0$ value in a standard cosmology. Our preliminary analysis focus on the role of several parameters: astrometry for the lens system, time delay between images, external convergence and mass model for the main lens galaxy

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