kids+viking: cosmic shear tomography with optical+ir data · 2019. 10. 15. · kids+viking: cosmic...
TRANSCRIPT
KiDS+VIKING: Cosmic shear tomography with optical+IR data
Hendrik Hildebrandt - Ruhr-University BochumGerman Centre for Cosmological Lensing (GCCL)
KiDS: Kilo Degree Survey DES: Dark Energy Survey
HSC: Hyper-Suprime Cam SurveyStage III SurveysVIKING
Stage III cosmic shear results
= σ 8
(Ωm
/0.3
)0.5
Hildebrandt et al. (2018)
George E.: Wrong or new physics?
2.3σ
Hildebrandt et al. (2018)
Hildebrandt et al. (2018)
Hildebrandt et al. (2018)
Hildebrandt et al. (2018)
KV450 photometric redshifts
Wright et al. (2018)Spec-z
Re-weight spec-z surveys to be more representative.
1. Magnitude space needs to be fully covered.2. Requires unique relation colour-redshift relation.
Redshift calibration with spec-z
Hildebrandt et al. (2017)
σ<z> ≈ 0.01 − 0.04
from bootstrapping
the data
cross-checked on MICE
simulations
Self-organising map of mag space
~99% coverage of 9D mag space in KV450.Wright et al. (2019)
KV450 “gold” sample
Wright et al. (2019)
~85% of the sources.
σ<z> ≈ 0.007
Spectroscopic calibration of DES-Y1
Caveat: Re-weighting done in 4D only.Joudaki et al. (2019)
0.1 0.2 0.3 0.4 0.5
≠m
0.72
0.80
0.88
0.96
S8
DES-Y1 (original n(z), KV450 setup)
DES-Y1 (KV450 setup)
Planck 2018
S8 constraints
Joudaki et al. (2019)
1.9σ tension between DES and Planck
0.1 0.2 0.3 0.4 0.5
≠m
0.7
0.8
0.9
S8
KV450
DES-Y1
KV450 + DES-Y1
Planck 2018
KV450 and DES-Y1 combined
Joudaki et al. (2019)
2.5σ tension between WL and Planck
3.2σ tension between WL and Planck
Asgari et al. submitted
KV450 cosmic shear + BOSS wedges
Tröster et al. (2019)
3.5σ tension between WL and Planck
(but only ~2.1σ over full parameter space)
Important: Sampling with ΛCDM, not geometric BAO
parameters.
Problems with the redshift calib.• Calibration with photo-z (e.g. COSMOS-2015):• Outliers => underestimate <z>• Bias => underestimate <z>
• Calibration with spec-z:• Magnitude-space coverage => underestimate <z>• Uniqueness of colour-redshift relation => underestimate <z>• Wrong spec-z => <z> drawn to the mean of all spec-z
=> We might still overestimate S8!
Summary & Outlook
• ~2-3σ tension in S8 between Planck and low-z WL measurements (KV450, DES-Y1 re-calibrated). Like H0 a few years ago?
• Are we “wrong”? Systematics? Redshift calibration?
• Other LSS probes show similar discrepancies. No S8 higher than Planck!Related to H0 crisis? Will this evolve into a serious problem for ΛCDM?
• Exciting times: KiDS+VIKING and DES finished; all 3 stage-III surveys analysing several times more data now.