Presentation on theme: "L. Perivolaropoulos Department of Physics University of Ioannina Open page."— Presentation transcript:
L. Perivolaropoulos Department of Physics University of Ioannina Open page
Talk Made in Corfu-Greece Summer 2006
Dark Energy Probes include -SnIa (Gold sample and SNLS), -CMB shift parameter (WMAP 3-year), -Baryon Acoustic Oscillation Peak in LSS surveys, -Cluster gas mass fraction, -Linear growth rate from 2dF (z=0.15) Some of these probes mildly favor an evolving w(z) crossing the phantom divide w=-1 over ΛCDM Minimally Coupled Quintessence is inconsistent with such crossing Scalar Tensor Quintessence is consistent with w=-1 crossing Extended Gravity Theories (DGP, Scalar Tensor etc) predict unique signatures in the perturbations growth rate Boisseau, Esposito-Farese, Polarski, Starobinsky 2000 LP 2005
Directly Observable Dark Energy (Inferred) No Yes Flat Friedmann Equation Not Consistent
z~0.5: Acceleration starts 157 SnIa from Spergel et. al Q: What causes this accelerating expansion? Flat
Chevalier-Polarski 2001, Linder 2003 Sahni et. al Huterer-Cooray 2004 Nesseris-LP 2004 Constant w Weller-Albrecht 2002 Pogosian et. al. 2005
All best fit parameterizations cross the phantom divide at z~0.25 The parametrization with the best χ 2 is oscillating Lazkoz, Nesseris, LP 2005
Espana-Bonet, Ruiz-Lapuente astro-ph/ Wang, Lovelace 2001 Huterer, Starkman 2003 Saini 2003 Wang, Tegmark 2005 Espana-Bonet, Ruiz-Lapuente 2005 Q: Do other SnIa data confirm this trend?
Trunc. Gold (140 points, z<1) Full Gold (157 points, z<1.7)SNLS (115 points z<1) SNLS data show no trend for crossing the phantom divide w=-1! S. Nesseris, L.P. Phys. Rev. D72:123519, 2005 astro-ph/
Q: Does R contain all the info about H(z) in the CMB Spectrum?
CMB Spectrum practically unaffected All the useful H(z) related info coming from the CMB spectrum is contained in R.
Gold dataset Riess -et. al. (2004) SNLS dataset Astier -et. al. (2005) Other data: CMB, BAO, LSS, Clusters S. Nesseris, L.P. in prep. Other data: CMB, BAO, LSS, Clusters Gold dataset Riess -et. al. (2004) SNLS dataset Astier -et. al. (2005) Other data: CMB, BAO, LSS, Clusters Minimize: Eisenstein et. al Wang, Mukherjee 2006 Allen et. al dF:Verde et. al. MNRAS 2002
What theory produces crossing of the w=-1?
+: Quintessence -: Phantom To cross the w=-1 line the kinetic energy term must change sign (impossible for single phantom or quintessence field) Generalization for k-essence:
ΛCDM (SnIa best fit, Ω m =0.26 ) DGP SnIa best fit + Flat Constraint Scalar Tensor (α=-0.5, Ω m =0.26 ) Flat Matter Only Verde et. al. MNRAS 2002 Hawkins et. al. MNRAS 2003
Interesting probes of the dark energy evolution include: - SnIa (Gold sample, SNLS) - CMB shift parameter - Baryon Acoustic Oscillations (BAO) Peak of LSS correlation (z=0.35) - Clusters X-ray gas mass fraction - Growth rate of perturbations at z=0.15 (from 2dFGRS) All recent data indicate that w(z) is close to -1. Thus w(z) may be crossing the w=-1 line. Minimally Coupled Scalar predicts no crossing of w=-1 line Scalar Tensor Theories are consistent with crossing of w=-1 Extended Gravity Theories (DGP, Scalar Tensor etc) predict unique signatures in the growth rate of cosmological perturbations
Growth Factor: Models degenerate in ISW are also degenerate in linear growth factor.
Hubble free luminosity Distance Apparent Magnitude: χ 2 depends on M: where Minimize:
Gold SampleSNLS Uniform Analysis of Data (light curves) by one Group Combination of Data from Various Instruments Use of a single ground based instrument (megaprime of CFH 3.6m telescope) Redshift Range 0