Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Cluster Cosmology Constraints from the 2500 deg$^2$ SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope

S. Bocquet, J. P. Dietrich, T. Schrabback, L. E. Bleem, M. Klein, S. W. Allen, D. E. Applegate, M. L. N. Ashby, M. Bautz, M. Bayliss, B. A. Benson, M. Brodwin, E. Bulbul, R. E. A. Canning, R. Capasso, J. E. Carlstrom, C. L. Chang, I. Chiu, H-M. Cho, A. Clocchiatti, T. M. Crawford, A. T. Crites, T. de Haan, S. Desai, M. A. Dobbs, R. J. Foley, W. R. Forman, G. P. Garmire, E. M. George, M. D. Gladders, A. H. Gonzalez, S. Grandis, N. Gupta, N. W. Halverson, J. Hlavacek-Larrondo, H. Hoekstra, G. P. Holder, W. L. Holzapfel, Z. Hou, J. D. Hrubes, N. Huang, C. Jones, G. Khullar, L. Knox, R. Kraft, A. T. Lee, A. von der Linden, D. Luong-Van, A. Mantz, D. P. Marrone, M. McDonald, J. J. McMahon, S. S. Meyer, L. M. Mocanu, J. J. Mohr, R. G. Morris, S. Padin, S. Patil, C. Pryke, D. Rapetti, C. L. Reichardt, A. Rest, J. E. Ruhl, B. R. Saliwanchik, A. Saro, J. T. Sayre, K. K. Schaffer, E. Shirokoff, B. Stalder, S. A. Stanford, Z. Staniszewski, A. A. Stark, K. T. Story, V. Strazzullo, C. W. Stubbs, K. Vanderlinde, J. D. Vieira, A. Vikhlinin, R. Williamson, A. Zenteno

TL;DR

This study derives cosmological constraints from the 2500 deg$^2$ SPT-SZ cluster sample by jointly fitting cosmology and observable–mass scaling relations, now augmented with direct weak-lensing mass calibration from Magellan and HST. It jointly fits three mass proxies—SZ significance $ξ$, X-ray $Y_ ext{X}$, and WL mass $M_ ext{WL}$—while modeling intrinsic scatter and cross-correlations and incorporating external Planck CMB, BAO, and Pantheon SN data to constrain a flat $νΛ$CDM model. The analysis yields $Ω_m=0.276±0.047$, $σ_8=0.781±0.037$, and $σ_8(Ω_m/0.3)^{0.2}=0.766±0.025$, with $w=-1.55±0.41$ in a $νw$CDM cosmology; growth measurements show no tension with General Relativity. The X-ray scaling relations ($Y_ ext{X}$–mass and $M_ ext{gas}$–mass) are consistent with self-similar evolution to within $1σ$, though the mass-slope deviations are at the $2.3$–$2.5σ$ level; the paper also provides updated redshift and mass estimates for the SPT sample and demonstrates the power of WL self-calibration in cluster cosmology.

Abstract

We derive cosmological constraints using a galaxy cluster sample selected from the 2500~deg$^2$ SPT-SZ survey. The sample spans the redshift range $0.25< z<1.75$ and contains 343 clusters with SZ detection significance $ξ>5$. The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with $0.29<z<1.13$ (from Magellan and HST) and X-ray measurements of 89 clusters with $0.25<z<1.75$ (from Chandra). We rely on minimal modeling assumptions: i) weak lensing provides an accurate means of measuring halo masses, ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter $E(z)$ with a-priori unknown parameters, iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat $νΛ$CDM model, in which the sum of neutrino masses is a free parameter, we measure $Ω_\mathrm{m}=0.276\pm0.047$, $σ_8=0.781\pm0.037$, and $σ_8(Ω_\mathrm{m}/0.3)^{0.2}=0.766\pm0.025$. The redshift evolution of the X-ray $Y_\mathrm{X}$-mass and $M_\mathrm{gas}$-mass relations are both consistent with self-similar evolution to within $1σ$. The mass-slope of the $Y_\mathrm{X}$-mass relation shows a $2.3σ$ deviation from self-similarity. Similarly, the mass-slope of the $M_\mathrm{gas}$-mass relation is steeper than self-similarity at the $2.5σ$ level. In a $νw$CDM cosmology, we measure the dark energy equation of state parameter $w=-1.55\pm0.41$ from the cluster data. We perform a measurement of the growth of structure since redshift $z\sim1.7$ and find no evidence for tension with the prediction from General Relativity. We provide updated redshift and mass estimates for the SPT sample. (abridged)

Cluster Cosmology Constraints from the 2500 deg$^2$ SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope

TL;DR

This study derives cosmological constraints from the 2500 deg SPT-SZ cluster sample by jointly fitting cosmology and observable–mass scaling relations, now augmented with direct weak-lensing mass calibration from Magellan and HST. It jointly fits three mass proxies—SZ significance , X-ray , and WL mass —while modeling intrinsic scatter and cross-correlations and incorporating external Planck CMB, BAO, and Pantheon SN data to constrain a flat CDM model. The analysis yields , , and , with in a CDM cosmology; growth measurements show no tension with General Relativity. The X-ray scaling relations (–mass and –mass) are consistent with self-similar evolution to within , though the mass-slope deviations are at the – level; the paper also provides updated redshift and mass estimates for the SPT sample and demonstrates the power of WL self-calibration in cluster cosmology.

Abstract

We derive cosmological constraints using a galaxy cluster sample selected from the 2500~deg SPT-SZ survey. The sample spans the redshift range and contains 343 clusters with SZ detection significance . The sample is supplemented with optical weak gravitational lensing measurements of 32 clusters with (from Magellan and HST) and X-ray measurements of 89 clusters with (from Chandra). We rely on minimal modeling assumptions: i) weak lensing provides an accurate means of measuring halo masses, ii) the mean SZ and X-ray observables are related to the true halo mass through power-law relations in mass and dimensionless Hubble parameter with a-priori unknown parameters, iii) there is (correlated, lognormal) intrinsic scatter and measurement noise relating these observables to their mean relations. We simultaneously fit for these astrophysical modeling parameters and for cosmology. Assuming a flat CDM model, in which the sum of neutrino masses is a free parameter, we measure , , and . The redshift evolution of the X-ray -mass and -mass relations are both consistent with self-similar evolution to within . The mass-slope of the -mass relation shows a deviation from self-similarity. Similarly, the mass-slope of the -mass relation is steeper than self-similarity at the level. In a CDM cosmology, we measure the dark energy equation of state parameter from the cluster data. We perform a measurement of the growth of structure since redshift and find no evidence for tension with the prediction from General Relativity. We provide updated redshift and mass estimates for the SPT sample. (abridged)

Paper Structure

This paper contains 10 sections, 8 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Data
  3. The SPT-SZ 2500 deg$^2$ Cluster Sample
  4. X-ray Measurements
  5. Weak Gravitational Lensing Data
  6. External Cosmological Data Sets
  7. Analysis Method
  8. Observable--mass Relations
  9. The SZ $\xi$--mass Relation
  10. The Weak-Lensing Observable--Mass Relation

Figures (2)

  • Figure 1: The SPT-SZ 2500 deg$^2$ cluster cosmology sample, selected to have redshift $z>0.25$ and detection significance $\xi>5$. Top panel: The distribution of clusters in redshift and mass (assuming a fiducial observable--mass relation). Black points show the full sample, blue dots mark those 89 clusters for which X-ray follow-up data from Chandra are available, and green triangles (orange squares) mark those 19 with Magellan/Megacam (13 with the Hubble Space Telescope) WL follow-up data. Bottom panel: Histograms with the same color coding. While the X-ray follow-up dataset covers the entire redshift range, the WL follow-up covers $0.25<z\lesssim1.1$.
  • Figure 2: Updates in cluster redshifts since the publication of the SPT-SZ cluster catalog bleem15b. Top panel: Original redshifts plotted against the updated ones. Black points show unchanged redshifts (without error bars for ease of presentation), orange error bars show updated photometric redshifts, and blue error bars show new spectroscopic measurements. Bottom panel: Changes in redshifts; we omit unchanged redshifts and all error bars. Orange points show the change in photo-$z$s, blue points show changes due to new spec-$z$ measurements.