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SUMMARY:Physical properties and redshift distributions of KiDS-1000 galaxi
 es using pop-cosmos - Dr Anik Halder (University of Cambridge)
DTSTART:20260318T134500Z
DTEND:20260318T141500Z
UID:TALK245836@talks.cam.ac.uk
CONTACT:Cristiano Longarini
DESCRIPTION:Accurate redshift calibration and physically motivated source 
 sample selection are central challenges for precision weak lensing cosmolo
 gy. In this talk\, I will present our recent work on forward modelling red
 shift distributions and inferring physical properties of weak lensing gala
 xies in the Kilo-Degree Survey (KiDS-1000) using a generative model for th
 e galaxy population. The framework enabling this work is pop-cosmos\, a ca
 librated galaxy population model that allows principled Bayesian inference
  of individual galaxy redshifts and physical properties for millions of Ki
 DS-1000 sources. Validation against spectroscopic samples demonstrates low
  bias and scatter in the inferred photometric redshifts\, while physical p
 roperty inference enables the construction of weak lensing catalogues that
  mitigate intrinsic alignment systematics. We also develop a forward-model
 ling framework to infer the redshift distributions of the KiDS-1000 galaxi
 es. By applying a KiDS data and survey selection model to synthetic photom
 etric data of mock pop-cosmos galaxies\, we directly characterize the reds
 hift distributions in each of the five tomographic bins of KiDS-1000\, the
 reby bypassing the need for spectroscopic reweighting used in conventional
  redshift calibration methods. Overall\, our results demonstrate how the p
 op-cosmos galaxy population model can deliver accurate redshift distributi
 ons as well as galaxy properties\, crucial for connecting galaxy evolution
  physics and weak lensing cosmology with Rubin LSST and Euclid.
LOCATION:Hoyle Lecture theatre + Zoom 
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