Cosmological Constraints from the XMM Cluster Survey (XCS) Martin Sahlén, for the XMM Cluster Survey Collaboration The Oskar Klein Centre for Cosmoparticle Physics Stockholm University
Key Points The XCS is the XMM-Newton equivalent of the ROSAT 400d survey; largest X-ray cluster survey to date (factor 4) Major potential for e.g. Cluster discovery Scaling relations Cosmology: ~2x on Ω m, σ 8, Σm ν & f NL > 30 might be testable Calibration of future surveys First data release (XCS-DR1) available Upcoming x2 Cosmological constraints constraints on e.g. from Ωthe M XCS, σ 8 /, M. w, Sahlén m ν, / γ, msa@fysik.su.se f NL 2/26
Complete XMM-Newton archive (serendipitous) >6000 observations, ~600 sq. deg. Science goals Find galaxy clusters Constrain cosmology using galaxy clusters Study redshift evolution of cluster gas (scaling relations) Study galaxy evolution in clusters Study properties of unusual X-ray sources, e.g. high-redshift quasars and isolated neutron stars www.xcs-home.org Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 3/26
Cluster Finding X-ray temperature, flux, redshift, spatial parameters Flux limit: ~5 x 10 14 erg s -1 cm -2 z max = 1.46 (so far) Final area: ~500 sq. deg. Several thousand clusters expected (3675 extended-source candidates so far) Targeted pointings excluded for cosmology (but useful for mass calibration) Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 4/26
Lloyd-Davies et al., arxiv:1010.0677 XMM observation pointings Green = DES footprint Area within red dashed lines (Galactic plane + Magellanic clouds) not used for clusters Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 5/26
XCS Data Release 1 Mehrtens et al. (2011) MNRAS submitted, arxiv:1106.3056 503 optically confirmed clusters (largest homogeneous X-ray cluster sample) 464 with redshift estimate 402 with temperature measurement 255 previously unknown clusters, 356 new to X-ray z>1: 10, T>5 kev: 67 Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 6/26
Current X-Ray Cluster Surveys Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 7/26
Current X-Ray Cluster Surveys Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 8/26
XCS-DR1 L T Relation 402 clusters Selection not included (L X -T X data not yet public) Most accurate L-T measurement to date valuable calibration for other surveys Lloyd-Davies et al, in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 9/26
0.1 < z < 0.3 T > 2 kev >300 counts 121 sq. deg. Measurement errors ignored First comparison: SDSS DR7 XCS-DR1 overlap 25 20 15 10 Observed clusters (SDSS DR7 overlap) Expected means, WMAP7 cosmology 41 6 observed, 36 expected mean 5 M.S. et al., in prep. 0 0.1 0.14 0.18 0.22 0.26 0.3 z Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 10/26
0.1 < z < 0.3 T > 2 kev >300 counts 121 sq. deg. Measurement errors ignored First comparison: SDSS DR7 XCS-DR1 overlap 25 20 15 10 Observed clusters (SDSS DR7 overlap) Expected means, WMAP7 cosmology 41 6 observed, 36 expected mean 5 M.S. et al., in prep. 0 2 3 4 5 6 7 8 9 T X [kev] Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 11/26
FORECASTS WORK IN PROGRESS Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 12/26
Predicted Detected Distributions XCS 500 Flat ΛCDM, Ω m = 0.3, σ 8 =0.8 T>2 kev, >500 photons M.S., P. Viana, A. Liddle, K. Romer et al. 2009 Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 13/26
Forecast Constraints Self-Calibrated L-T Relation w/ Scatter XCS 500 Results Self-calibration σ(ω of L-T m ) < 0.03 σ(σ 8 ) < 0.05 Note: not using flux measurements Fixed M-T (HIFLUGCS), 0.1 < z < 1 4 L-T parameters marginalized over Number counts only (serendipitous) M.S., P. Viana, A. Liddle, K. Romer et al. 2009 Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 14/26
Mean # clusters in bin ( z=0.05) 100 90 Predicted Detected Distributions XCS 300 Self-similar L-T relation Constant L-T relation 80 70 60 50 40 30 20 10 Flat ΛCDM, Ω m = 0.266, σ 8 =0.801 T>2 kev, >300 photons 1250 860 ~300 photons limit for small T (hence M) uncertainties ~3/4 increase in clusters by lowering the threshold 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 z Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 15/26 M.S. et al., in prep.
XCS 300 Forecast: ΛCDM Fiducial model Ω M = 0.266 Ω b = 0.0449 h = 0.71 σ 8 = 0.801 n S = 0.963 σ(α M-T ) = 15% 0.75 0.8 0.85 σ8 = 0.80 ± 0.01, ±0.02 Ω M = 0.266 ± 0.005, ±0.010 Varying σ 8 Ω M α M-T m 0.28 0.27 0.26 0.25 0.78 0.8 0.82 8 0.24 0.26 0.28 0.3 m α M-T is the normalization of the mass temperature (M T) relation, here used to illustrate many possible mass-calibration uncertainties M.S. et al., in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 16/26
Comparison to Current Results Works of 400d (Vikhlinin et al. 2009) and Allen group (Mantz et al. 2010) set a gold standard In a like-for-like comparison, we expect an improvement in constraints by a factor ~2 (based on numbers) or more (redshift coverage) Mantz et al. find σ(ω M ) = 0.04, σ(σ 8 ) = 0.05, which matches this expectation quite well Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 17/26
0.76 0.8 0.84 Forecast: m /ev XCS 300 Neutrino masses Σm ν /ev < 0.86 (0.95), 95% CL σ 8 = 0.80 ± 0.01, ±0.02 Ω M = 0.27 ± 0.01, ±0.02 Fiducial model Ω M = 0.266 Ω b = 0.0449 Σm ν = 0.0 ev h = 0.71 σ 8 = 0.801 n S = 0.963 σ(α M-T ) = 15% Fitting σ 8 Ω M Σm ν α M-T m 0.3 0.26 0.22 0.76 0.8 0.84 0.22 0.26 0.3 Work in progress, ultimately expect x2 improvement on CMB+clusters constraint 2 1 2 1 0 0.76 0.8 0.84 8 0 0.22 0.26 0.3 m 0 1 2 m /ev M.S. et al., in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 18/26
Forecast: Neutrino masses m /ev XCS 300 0.76 0.8 0.84 Σm ν /ev= 1.00 ± 0.40, ±0.43 σ 8 = 0.80 ± 0.02, ±0.03 Ω M = 0.27 ± 0.02, ±0.03 Fiducial model Ω M = 0.266 Ω b = 0.0449 Σm ν = 1.0 ev h = 0.71 σ 8 = 0.801 n S = 0.963 σ(α M-T ) = 15% Fitting σ 8 Ω M Σm ν α M-T m 0.3 0.26 0.22 0.76 0.8 0.84 0.22 0.26 0.3 Work in progress, ultimately expect x2 improvement on CMB+clusters constraint 2 1 2 1 0 0.76 0.8 0.84 8 0 0.22 0.26 0.3 m 0 1 2 m /ev M.S. et al., in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 19/26
XCS 300 Forecast: Non-Gaussianity f NL = 0 ± 16, ±51 f NL = 90 ± 16, ±52 Fiducial model Ω M = 0.266 Ω b = 0.0449 h = 0.71 σ 8 = 0.801 n S = 0.963 f NL = 0 and 90 σ(α M-T ) = 15% Fitting f NL α M-T -150-100 -50 0 50 100 150 local f NL Here using XCS 300 clusters up to z = 1.75-50 0 50 100 150 200 250 local f NL M.S. et al., in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 20/26
Other work in preparation: The Bayes Diet Bias! for overweight galaxy clusters M obs = 7.7 ± 1.1 x 10 14 h -1 M solar Can t idealize selection! M obs = 7.7 ± 3.7 x 10 14 h -1 M solar M t ~ 5.8 x 10 14 h -1 M solar Mass [10 15 h -1 M solar ] Mass [10 15 h -1 M solar ] M.S., in prep. Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 21/26
Conclusions The XMM Cluster Survey has released XCS- DR1, publicly available at www.xcs-home.org It is the largest homogeneous X-ray cluster sample to date, with 503 clusters, extending to high redshifts We find (in SDSS DR7 overlap) a distribution of clusters that agrees with a WMAP7 ΛCDM cosmology Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 22/26
Conclusions First cosmological constraints this year; next year considerable improvement [σ 8, Ω m, w, m ν, f NL, γ, ] With strong priors on Ω b, h, n S : Parameter Best-case σ Worst-case(?) σ Ω m ~ 0.02 ~ 0.03 σ 8 ~ 0.01 ~ 0.03 Σm ν * ~ 0.4 ev ~ 0.5 ev * but using e.g. full CMB covariance considerably better Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 23/26
Conclusions With strong priors on Ω b, h, Ω M & σ 8, n S : Parameter Best-case σ Worst-case(?) σ f NL ~ 15 ~ 50 Detailed constraints and forecasts in prep. Claims of too massive clusters often based on heavily biased mass estimates; in my opinion most likely no tension with ΛCDM Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 24/26
Other ideas Forecasts for e.g. XXL, erosita Quintessence models Public CosmoMC cluster module Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 25/26
THANK YOU http://okc.albanova.se Cosmological constraints from the XCS / M. Sahlén / msa@fysik.su.se 26/26