Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                

Dark Energy Survey Year 3 results: Exploiting small-scale information with lensing shear ratios

C. Sánchez et al. (DES Collaboration)
Phys. Rev. D 105, 083529 – Published 26 April 2022
PDFHTMLExport Citation
Abstract
Authors
See Also
Article Text
  • INTRODUCTION
  • DATA AND SIMULATIONS
  • MODELING OF THE RATIOS
  • MEASUREMENT AND COVARIANCE OF THE RATIOS
  • VALIDATION OF THE MODEL
  • COMBINATION WITH OTHER PROBES AND EFFECT…
  • RESULTS WITH THE DES Y3 DATA
  • SUMMARY AND CONCLUSIONS
  • ACKNOWLEDGMENTS
  • APPENDICES
    • References

    Abstract

    Using the first three years of data from the Dark Energy Survey (DES), we use ratios of small-scale galaxy-galaxy lensing measurements around the same lens sample to constrain source redshift uncertainties, intrinsic alignments and other systematics or nuisance parameters of our model. Instead of using a simple geometric approach for the ratios as has been done in the past, we use the full modeling of the galaxy-galaxy lensing measurements, including the corresponding integration over the power spectrum and the contributions from intrinsic alignments and lens magnification. We perform extensive testing of the small-scale shear-ratio (SR) modeling by studying the impact of different effects such as the inclusion of baryonic physics, nonlinear biasing, halo occupation distribution descriptions and lens magnification, among others, and using realistic N-body simulations of the DES data. We validate the robustness of our constraints in the data by using two independent lens samples with different galaxy properties, and by deriving constraints using the corresponding large-scale ratios for which the modeling is simpler. The results applied to the DES Y3 data demonstrate how the ratios provide significant improvements in constraining power for several nuisance parameters in our model, especially on source redshift calibration and intrinsic alignments. For source redshifts, SR improves the constraints from the prior by up to 38% in some redshift bins. Such improvements, and especially the constraints it provides on intrinsic alignments, translate to tighter cosmological constraints when shear ratios are combined with cosmic shear and other 2pt functions. In particular, for the DES Y3 data, SR improves S8 constraints from cosmic shear by up to 31%, and for the full combination of probes (3×2pt) by up to 10%. The shear ratios presented in this work are used as an additional likelihood for cosmic shear, 2×2pt and the full 3×2pt in the fiducial DES Y3 cosmological analysis.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    10 More
    • Received 3 June 2021
    • Accepted 7 March 2022

    DOI:https://doi.org/10.1103/PhysRevD.105.083529

    © 2022 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Cosmological parametersCosmologyDark energyDark matterGravitational lensesLarge scale structure of the UniverseOptical, UV, & IR astronomy
    Gravitation, Cosmology & Astrophysics

    Authors & Affiliations

    Click to Expand

    See Also

    Dark energy survey year 3 results: High-precision measurement and modeling of galaxy-galaxy lensing

    J. Prat et al. (DES Collaboration)
    Phys. Rev. D 105, 083528 (2022)

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 105, Iss. 8 — 15 April 2022

    Reuse & Permissions
    Access Options
    CHORUS

    Article Available via CHORUS

    Download Accepted Manuscript
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      Top panel: redshift distributions of redmagic lens galaxies divided in five redshift bins. The first three redshift bins are used for the shear ratio analysis in this work, while the two highest-redshift ones (in gray) are not used. The n(z)  s are obtained by stacking individual p(z) distributions for each galaxy, as computed by the redmagic algorithm, and validated using clustering cross-correlations in Cawthon et al. [45]. Middle panel: same as above but for the maglim lens galaxy sample. The redshift distributions come from the directional neighborhood fitting photometric redshift algorithm [40, 46]. Bottom panel: the same but for the weak lensing source galaxies, using the metacalibration sample. In this case the redshift distributions come from the SOMPZ (self-organizing maps photometric redshifts) and WZ methods, described in Myles et al. [47] and Gatti et al. [48].

      Reuse & Permissions
    • Figure 2
      Figure 2

      Lensing ratios using the full model of the ratios we use in this work as a function of scale evaluated at the best-fit values of the 3×2pt analysis (see Sec. 3b) compared with the purely geometrical model used in previous shear-ratio analyses until this date, which is scale independent (see Sec. 3a). We can appreciate the geometrical component still dominates the modeling of the ratios but small but significant deviations are found when comparing with the full modeling. The unshaded regions correspond to the “small scales” we use in this analysis, which are adding extra information below the scales used in the 3×2pt cosmological analysis for the galaxy-galaxy lensing probe. The gray shaded regions are not used for the fiducial ratios in this work.

      Reuse & Permissions
    • Figure 3
      Figure 3

      Impact of different IA models (different parameter choices for TATT) on all the lensing ratios considered in this work. We find that for ratios whose modeling is close to a pure geometrical model (Fig. 2) the impact of IA is negligible. The different lines in the plot have different IA parameters in the ranges: a1=[0.5,1],a2=[−2,−0.8],α1=[−2.5,0],α2=[−4.,−1.2],bTA=[0.6,1.2]. The gray bands show the size of the data uncertainties on the ratios, for reference.

      Reuse & Permissions
    • Figure 4
      Figure 4

      Upper panel: true values of the ratios {r} for our fiducial theory model, together with the estimates of the simulated ratios using the measurement procedure described in Sec. 4a3 and the uncertainties estimated using the procedure described in Sec. 4a4. Middle panel: measured set of shear ratios and their uncertainties in the redmagic data, together with the best-fit model from the 3×2 DES Y3 cosmological analysis of the redmagic sample (χ2/ndf=11.3/9, p value of 0.26). Lower panel: measured set of shear ratios and their uncertainties in the maglim data, together with the best-fit model from the 3×2 DES Y3 cosmological analysis of the maglim sample (χ2/ndf=18.8/9, p value of 0.03, above the threshold for inconsistencies which we originally set at p value =0.01 for the DES Y3 analysis).

      Reuse & Permissions
    • Figure 5
      Figure 5

      Distribution of χs2 from Eq. (28), for small and large-scale ratios, compared to a chi squared distribution with a number of degrees of freedom equal to the numbers of ratios in {r}s.

      Reuse & Permissions
    • Figure 6
      Figure 6

      Summary of the posteriors on the model parameters corresponding to source redshifts, shear calibration and lens redshifts for different SR-only test runs described in Sec. 5 and combination runs from Sec. 6. All the above tests are performed using noiseless simulated data vectors except for the Buzzard ones which include noise. The colored bands show the 1σ prior in each parameter, while the black error bars show 1σ posteriors.

      Reuse & Permissions
    • Figure 7
      Figure 7

      This plot summarizes the posteriors on the two intrinsic alignment model parameters that are constrained by the ratios, for different SR only test runs described in Sec. 5, using noiseless simulated data vectors.

      Reuse & Permissions
    • Figure 8
      Figure 8

      Effects of HOD modeling and HOD evolution on the shear ratios, for both small and large angular scales. The error bars show the ratio uncertainties from the same covariance as used in the data.

      Reuse & Permissions
    • Figure 9
      Figure 9

      Impact of different effects on the lensing ratios, including cosmology dependence (see Sec. 5e), boost factors (see Sec. 5f) and reduced shear+source magnification (see Sec. 5g). All these tests use noiseless simulated data vectors, and the error bars show the ratio uncertainties from the same covariance as used in the data.

      Reuse & Permissions
    • Figure 10
      Figure 10

      Simulated likelihood analysis showing the constraints on cosmological parameters S8 and Ωm and intrinsic alignments parameters a1IA and a2IA from cosmic shear only (1×2pt) and cosmic shear and lensing ratios (1×2pt+SR).

      Reuse & Permissions
    • Figure 11
      Figure 11

      Mean source redshift constraints from a SR-only chain, with a flat uninformative prior, in comparison with the results from the combination of the alternative calibration methods of SOMPZ+WZ, and the final combined results of SOMPZ+WZ+SR on data using the redmagic sample.

      Reuse & Permissions
    • Figure 12
      Figure 12

      Mean source redshift constraints from different SR configurations, using the DES Y3 redshift prior (SOMPZ+WZ), comparing the fiducial small-scale constraints from those of the LS SR, for the two independent lens galaxy samples, redmagic and maglim.

      Reuse & Permissions
    • Figure 13
      Figure 13

      Data constraints on the two intrinsic alignment amplitude model parameters from different DES Y3 SR data configurations, comparing the fiducial small-scale constraints from those from the LS SR, for the two independent lens galaxy samples, redmagic and maglim.

      Reuse & Permissions
    • Figure 14
      Figure 14

      Differences in the DES Y3 data constraints on cosmological parameters S8 and Ωm with the addition of SR to the cosmic shear measurement (1×2pt). The left panel shows the case with SR using redmagic lenses, while the right panel shows the results with SR using the maglim lens sample. All the contours in the plot have been placed at the origin of the ΔΩm−ΔS8 plane, so that the plot shows only the impact of SR in the size of contours but does not include information on the central values of parameters or shifts between them. The impact of SR is significantly relevant for cosmic shear, with improvements in constraining S8 of 31% for redmagic SR and 25% for maglim SR.

      Reuse & Permissions
    • Figure 15
      Figure 15

      DES Y3 data constraints on the two intrinsic alignment amplitude model parameters from the full combination of probes (3×2pt) with and without the addition of SR, for the redmagic and maglim lens samples. The crossing of the dashed black lines shows the no IA case.

      Reuse & Permissions
    • Figure 16
      Figure 16

      Correlation matrix for the lensing ratios, on the left panel using the redmagic lens sample and on the right panel using the maglim sample.

      Reuse & Permissions
    • Figure 17
      Figure 17

      Constraints on the five parameters of the IA model described in Sec. 3 given the combination of SR and the other 2pt functions, using simulated DES Y3 data.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review D

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×