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SUMMARY:Reanalysis of KiDS-1000 cosmic shear using MetaCalibration - Mijin
  Yoon (Leiden)
DTSTART:20250117T113000Z
DTEND:20250117T123000Z
UID:TALK225694@talks.cam.ac.uk
CONTACT:Sandro Tacchella
DESCRIPTION:Weak lensing surveys estimate the clustering of matter in the 
 Universe by measuring the correlations in galaxy shapes. These surveys are
  powerful tools for constraining cosmological model parameters in the near
 by Universe. However\, most weak lensing surveys estimate the matter clump
 iness (S8) to be lower than the value derived from Planck cosmic microwave
  background (CMB) observations. A better understanding of this difference 
 is crucial\, as it may point to new physics.\nAn accurate weak lensing ana
 lysis is becoming more challenging as we increase statistical power by ups
 caling survey observations. One of the key steps in the weak lensing analy
 sis is the ‘shear’ estimation\, which quantifies the apparent change i
 n galaxy ellipticities due to lensing. Within the Kilo-Degree Survey (KiDS
 ) team\, we recently developed a new shear estimation pipeline\, based on 
 MetaCalibration\, to complement the existing fiducial pipeline (Lensfit). 
 Performance tests demonstrate that MetaCalibration is robust and less depe
 ndent on the fidelity of the image simulations. Using this new pipeline\, 
 we derive revised cosmological constraints for KiDS. Furthermore\, both Ki
 DS shear pipelines are now being implemented in Euclid\, enabling robust w
 eak lensing analyses and facilitating scientific breakthroughs by observin
 g billions of galaxies.
LOCATION:Ryle Seminar Room\, KICC + online
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