The impact of the REFLEX cluster survey in cosmology Ariel Sánchez A.Balaguera-Antolinez, H. Boehringer, L. Guzzo, C. Collins, P. Schuecker Vulcano Workshop 2010 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Outline • Introduction: cosmology with clusters of galaxies • The REFLEX catalogue • The impact of REFLEX on cosmology • The near future: REFLEX II Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction Clusters as cosmological probes • Clusters are the largest clearly defined structures • Tracers of the large scale structure of the Universe. • n ( M,z ) : depends strongly on Ω m , w DE and σ 8 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction Clusters as cosmological probes Λ CDM Borgani & Guzzo (2001) EdS Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction Clusters as cosmological probes • X-ray emission is a good tracer of gravitational potential • Simple scaling relations between observables (e.g. L X , T X ) and mass. • Simple selection functions: flux limited samples Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction Clusters as cosmological probes • X-ray emission is a good tracer of gravitational potential • Simple scaling relations between observables (e.g. L X , T X ) and mass. Pratt et al. (2010) • Simple selection functions: flux limited samples Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction The REFLEX catalogue • REFLEX (ROSAT-ESO Flux Limited X-ray) Cluster Survey. • Largest statistically complete X-ray selected sample to date. • Combines X-ray data from RASS and ESO follow-up optical observations. • Flux limited sample: f X � 3 � 10 � 12 ergs � 1 cm � 2 ( ) 0.1 � 2.4 kev • Contains 452 clusters with z < 0.45. Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction The REFLEX catalogue Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Introduction The REFLEX catalogue Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology One-point statistics: cluster abundance • The luminosity function: observational proxy for n ( M ) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology One-point statistics: the luminosity function • REFLEX N ( z ) (Schuecker et al. 2003) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology One-point statistics: cluster abundance • N ( z ) contains cosmological information in two ways Mass Volume selection: Mass element L X - M and function limiting L X Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology One-point statistics: the luminosity function • REFLEX N ( z ) (Schuecker et al. 2003) • Strong degeneracy between Ω m and σ 8 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the correlation function • Two-points statistics are the most used tools for LSS • The two-point correlation function is given by d V 2 r r 12 d V 1 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the correlation function • Two-points statistics are the most used tools for LSS • The two-point correlation function is given by d V 2 r r 12 d V 1 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the correlation function • The REFLEX correlation function (Collins et al. 2000) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the correlation function • REFLEX data is inconsistent with models with Ω m = 1 • Models with Ω m = 0.3 give a much better fit to the data. Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum • The power spectrum is the Fourier transform of ξ ( r ). • Clusters are biased tracers of the underlying density field Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum • The REFLEX P ( k ) (Schuecker et al. 2001) • Excellent agreement with P ( k ) of optically selected galaxies. • Ruled out strongly non- linear biasing models. b cg � 2.6 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum � m = 0.3, � � = 0.7 Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum • The combination of P ( k ) and N ( z ) improves the constraints • The degeneracy between Ω m and σ 8 is broken. � m = 0.34 ± 0.030 (stat.) ± 0.08(sys.) � 8 = 0.711 ± 0.035 (stat.) ± 0.14(sys.) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum Schuecker (2005) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX & cosmology Two-point statistics: the power spectrum Tegmark & Zaldarriaga (2002), Schuecker (2005) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX Il The present: REFLEX II • The enduring value of all-sky surveys: REFLEX II • Extension to f X � 1.8 � 10 � 12 ergs � 1 cm � 2 ( ) 0.1 � 2.4 kev Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX Il The present: REFLEX II • Same footprint as REFLEX • Extension of NORAS (northern hemisphere) ongoing Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
REFLEX Il The present: REFLEX II • Several ongoing analysis: Φ ( L x ), ξ ( r ), P ( k ), ξ cg ( r ), ξ ( σ , π )… • Goal: obtain robust constraints on cosmological parameters Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Mock catalogues Mock catalogues Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Mock catalogues The M - L X relation Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The two-point correlation function • We measured the ξ ( r ) of the catalogue and the mocks for different L X cuts. • Amplitude increase with increasing luminosity • Good agreement with mock Sánchez et al. (in prep. ) catalogues Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum Balaguera-Antolinez et al. (in prep.) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum • Flux-limited samples suffer an important problem • Larger distances probed by more luminous clusters • Introduces a scale dependent distortion in the shape of P ( k ) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum • Shape of P ( k ) for flux-limited samples is distorted. • This introduces biases in the obtained constraints • PVP estimator corrects for this effect giving good agreement with volume limited samples Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
• REFLEX was the largest statistically complete X-ray selected cluster sample. • Large impact in cosmology: helped to establish the concordance cosmological model. • This legacy will be continued by the REFLEX II & NORAS II • The goal: robust constraints on cosmological parameters with clusters of galaxies. Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics Constraints on cosmological parameters • Best current constraints: Sánchez et al. (2009) • With CMB + shape of P ( k ) w DE ~ 20% • Full P ( k ) information + Φ ( L X ) : w DE ~ 10% Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
The data The luminosity function • We fitted this Φ ( L X ) using a Schechter function (solid line): • We constructed an extended Schechter function by Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Mock catalogues The M - L X relation • Assign luminosities to halos according to with • We assume a log-normal scatter of σ log L = 0.114 • We add a 20% error in L X Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Mock catalogues Mock catalogues • Fit parameters A , b 1 and b 2 using a MCMC technique in order to reproduce the REFLEX II Φ ( L X ) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Two-point statistics The power spectrum • To correct for this: weight halos according to their bias (Percival, Verde & Peacock 2005) Ariel Sánchez The impact of REFLEX in cosmology Vulcano 24/05/10
Recommend
More recommend
