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Combining Different Measurements

Combining Different Measurements. Bob Nichol, ICG Portsmouth Tommaso Giannantonio, H-J Seo, Dan Carson , Hubert Lampeitl *, Josh Frieman, Bruce Bassett, Mat Smith, Will Percival (for SDSS Collaboration). * see poster. BAO with Redshift. Measure ratio of volume averaged distance

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Combining Different Measurements

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  1. Combining Different Measurements Bob Nichol, ICG Portsmouth Tommaso Giannantonio, H-J Seo, Dan Carson, Hubert Lampeitl*, Josh Frieman, Bruce Bassett, Mat Smith, Will Percival (for SDSS Collaboration) * see poster

  2. BAO with Redshift Measure ratio of volume averaged distance D0.35 /D0.2 = 1.812 ± 0.060 Flat CDM = 1.67 Systematics (damping, BAO fitting) also ~1Next set of measurements will need to worry about this 99.74% detection z~0.2 143k + 465k 79k z~0.35 Percival et al. (2006) Percival et al. 2007

  3. Cosmological Constraints Flatness assumed, constant w With CMB Only D0.35 /D0.2 W w= P/ 3 1 Favors w<-1 at 1.4 2 m

  4. Cosmological Constraints Flatness assumed m = 0.249 ± 0.018 w = -1.004 ± 0.089 With CMB Only D0.35 /D0.2 W W w= P/ 3 1 D0.35 /D0.2 = 1.66 ± 0.01 2 m m

  5. Discrepancy? • 2.4 difference between SN & BAO. The BAO want more acceleration at z<0.3 than predicted by z>0.3 SNe • ~1 possible from details of BAO damping - more complex then we thought • Assumption of flatness and constant w needs to be revisited

  6. Revisit with SDSS SNe Only look at measurements at z<0.4 • 500 Ia’s • 102 from 05 • LCDM line • 2s contours • q0 = -0.34 (2s) SDSS BAO points

  7. Cosmological Constraints Only look at measurements at z<0.4 • ISW (z<0.4) • Peacock et al Flat wCDM W SNe BAO w= -1 (15% stat & sym) SDSS BAO points

  8. Curvature Only look at measurements at z<0.4 • ISW (z<0.4) • Peacock et al

  9. Distance Duality Returning to BAO and SN discrepancy?

  10. Cosmic Chronometers Age of galaxies constraints age of universe (Jimenez & Loeb 2002) 5500 LRGs Carson et al. (in prep) (Using Thomas et al. models, marginalised over alpha-enhancement and metallicity)

  11. Cosmic Chronometers II Age of galaxies constraints age of universe (Jimenez & Loeb 2002) ALL FLAT raw t(z) HST TSR ISW WMAP

  12. Differential Ages H(z) We find H(z=0.2) ~ 80 +/- 12 km/s Same value as Gaztanaga et al. but not yet competitive in error

  13. Tension remains between BAO and SN (over same redshift range). But ~2s at best Cosmic Chronometers provide constraints on age-redshift relation (thus h and Wm). Also provide constraints on H(z) but not yet competitive BOSS could do much better, especially if we can do better on the stellar modeling (Maraston et al.) Conclusions

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