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SUMMARY:Deciphering CMB measurements with volunteer computing and Bayesian
  thinking - Marius Milea
DTSTART:20171127T130000Z
DTEND:20171127T140000Z
UID:TALK95359@talks.cam.ac.uk
CONTACT:Tobias Baldauf
DESCRIPTION:The Planck satellite has provided exquisite measurements of co
 smic microwave background (CMB) temperature and polarization\, measuring s
 cales in the CMB which had never before been probed. While finding overall
  good agreement with predictions from the standard LCDM model of cosmology
 \, Planck also found some tantalizing hints of beyond LCDM physics in the 
 form of shifts in the constraints on some parameters as compared to previo
 us measurements. For example\, the inferred Hubble constant shifted to ∼
 67 km/s/Mpc\, lower than before and in larger tension with non-CMB measure
 ments of this value. I will describe our efforts to quantify and understan
 d these shifts within the Planck data\, and how we used the massive comput
 ing resources provided by the volunteer computing cluster that I run\, Cos
 mology@Home\, to do so. Some of these shifts are related to an apparent en
 hancement in the amount of gravitational lensing in the Planck maps\, and 
 this effect stands to be further elucidated by high-fidelity measurements 
 of the lensing potential by future CMB probes such as CMB-S4. The analysis
  of such data\, however\, poses a challenge as our current lensing estimat
 ors will be statistically sub-optimal at future noise-levels. I will descr
 ibe our recent work building new optimal Bayesian tools for CMB lensing an
 alysis\, including a new reformulation of weak gravitational lensing calle
 d LenseFlow which may have useful applications beyond the CMB\, e.g. to ga
 laxy\, Lyman-alpha\, or 21cm lensing.
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Room]
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