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           OATS-UNI/TS SEMINAR
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Adriano Agnello (Niels Bohr Inst. Univ. of Copenhagen, DK)

Masses, Distances and Big Data

ABSTRACT:  Our understanding of cosmology is tied to that of galaxies and their halos. Weak-lensing experiments that aim at measuring departures from concordance cosmology need to probe scales <~2Mpc where baryonic effects dominate. Recent weak lensing results cast doubt on our ability to extract accurate cosmological information, especially in the foreseen regime of the LSST. I will revisit these results, with a reference to different cosmological simulations. I will also show an alternative approach to measure accurate galaxy masses directly, based on strong lens samples. I will then show how some of these lenses can be used to measure cosmological distances and hence the expansion history of the Universe. The current tension between late-Universe probes (including lenses) and early-Universe CMB measurements points at hitherto unknown systematics or departures from concordance cosmology and the standard model. Large lens samples are needed to reach high accuracy in cosmographic measurements, unveil unknown systematics, and/or secure the current tension to high significance. Therefore, in the last part of this talk I will show our recent efforts to mine these rare systems from the large databases of (current and upcoming) wide-field surveys.