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Five Innovative Methods to Measure Dark Energy

This presentation explores five groundbreaking methods to measure dark energy, an essential aspect of our understanding of the universe. The discussion includes insights into direct and indirect evidence of dark energy from Cosmic Microwave Background (CMB) studies, Type Ia Supernovae, gamma-ray bursts, and the analysis of galaxy voids. We will also examine advancements in cluster physics and their implications on dark energy density. The aim is to refine our understanding of dark energy's properties and its contribution to the universe's evolution using current and future data.

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Five Innovative Methods to Measure Dark Energy

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  1. Five Ways to Measure Dark Energy Yongzhong Xu Los Alamos National Laboratory Dark Matter & Dark Energy CCAST July 4-8th, 2005

  2. #1 Science Breakthrough in 1998 DM&DE,Jul 4-8

  3. #1 Science Breakthrough in 2003 DM&DE,Jul 4-8

  4. Outline • What do we know about dark energy? • How to constrain the dark energy density? (also in Prof. Fan’s talk) • CMB + LSS (power spectra), CMB x LSS (ISW) • Type Ia Supernovae (SNAP) • Cluster physics (abundance evolution, SZ+X-ray, lensing, fgas) • Gamma-ray bursts • Galaxy voids? • Summary DM&DE,Jul 4-8

  5. What we know? • Dark Energy exists • Indirect evidences (WMAP+2dFGRS, SDSS+WMAP) • Direct evidences (Integrated Sachs-Wolfe Effect) • WMAP x SDSS (Scranton etal.) • WMAP x 2MASS • Dark Energy Density (~70%) • w ~ -1 • Others? Nothing! DM&DE,Jul 4-8

  6. First result from WMAP Spergel et al., 2003 DM&DE,Jul 4-8

  7. w from WMAPext+2dfGRS DM&DE,Jul 4-8

  8. w from SDSS+WMAP Tegmark etal. 2004 DM&DE,Jul 4-8

  9. W from SDSS+WMAP DM&DE,Jul 4-8

  10. ISW Effect Hu 2004 DM&DE,Jul 4-8

  11. Detect ISW Effect Scranton et al. 2003 DM&DE,Jul 4-8

  12. Type Ia Supernovae (SNAP) DM&DE,Jul 4-8

  13. What SNAP Expects DM&DE,Jul 4-8

  14. Evolution of Cluster Abundance • Clusters in current redshfit surveys • Finding clusters in SDSS and/or 2dFGRS • Evolution of cluster abundance • Clusters in future surveys • LAMOST • Dark Energy Survey (one of the proposals for JDEM) DM&DE,Jul 4-8

  15. Finding Clusters in SDSS • Voronoi Tessellation • More than 3,000 clusters found in DR3 DM&DE,Jul 4-8

  16. Dark Energy Survey DM&DE,Jul 4-8

  17. Dark Energy Survey DM&DE,Jul 4-8

  18. Gamma-Ray Bursts Ghirlanda, Ghisellini, & Lazzati, 2004 Dai, Liang, & Xu, 2004 Atteia et al. 2003 DM&DE,Jul 4-8

  19. Galaxy Voids • 95% volume • Low mass, underdensity • About 1,000 voids found in SDSS DR3 • More dark energy in voids? DM&DE,Jul 4-8

  20. Summary • There are various methods to constrain the dark energy density and the equation of state w • Hopefully, we can constrain the evolution of w(z) using the current and future data • Can we use voids to measure dark energy? DM&DE,Jul 4-8

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