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IS IT POSSIBLE TO OBSERVATIONALLY DISTINGUISH ADIABATIC QUARTESSENCE FROM CDM? Luca Amendola 1, Martin Makler 2, Ribamar R. R. Reis 3 and Ioav Waga 3 1 INAF/Osservatorio Astronomico di Roma, 2 Centro Brasileiro de Pesquisas Físicas, 3 Instituto de Física – Universidade Federal do Rio de Janeiro

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THE COSMOLOGICAL STANDARD MODEL

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The non-relativistic, pressureless, matter is predominantly dark and non-baryonic (from Big Bang Nucleosynthesis). The universe seems to be dominated by a smooth component that drives the accelerated expansion. The spatial curvature is very close to zero (from CMB). Allen et al. – astro-ph/0405340 K.G. Begeman, A.H. Broeils, R.H. Sanders, MNRAS 249 (1991) 523.

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SOME IMPORTANT QUESTIONS: - What is the nature of the Dark Matter? - What is the nature of the Dark Energy? -Could these components be different aspects of the same substance?

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UNIFYING DARK MATTER OR QUARTESSENCE A prototype – the generalized Chaplygin Gas. Chaplygin Gas ( =1) – initially suggested as an alternative to quintessence Kamenshchik et al. PLB 511, 265 (2001). Motivation: D-Branes. Dark matter regimeDark energy regime

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For every quartessence model, the density decreases towards to a minimum value min and remains constant. In this phase, it behaves like a cosmological constant (w=-1). w<-1 is forbidden for such models

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BACKGROUND DEPENDENT OBSERVATIONAL CONSTRAINTS Makler, Quinet & Waga PRD 68,123521, 2003 SNeIa + Clusters + Radio-galaxies + weak lensing

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PROBLEMS – LINEAR PERTURBATIONS Sandvik, Tegmark, Zaldarriaga e Waga, Phys. Rev. D 69, 123524 (2004). Beça et al.- PRD 67,101301,2003 Reis, Waga, Calvão & Jorás –PRD 68,061302 (2003). L. Amendola, I. Waga e F. Finelli, JCAP 11, 009 (2005) = - 0.1 = 0 = 0.1 = 0.2

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PERTURBATION THEORY IN COSMOLOGY

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Linear evolution equations in synchronous gauge (A=B=0) for a multi-component fluid. Assuming vanishing spatial curvature and anisotropic stress, and conservation of the energy-momentum tensor of each component.

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ORIGIN OF THE PROBLEM SOLUTION: A finite sound speed in recent times is responsible for the instabilities in the power spectrum Reis et al., Phys. Rev. D 68, 061302(R) (2003)

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L. Amendola, I. Waga e F. Finelli, JCAP 11, 009 (2005) CHAPLYGIN

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OTHER CASES Reis, Makler e Waga, Class. Quant. Grav. 22, 353 (2005), Erratum-ibid.22, 1191 (2005). = 0 = 0.1 = 0.2 = 0.3

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OTHER CASES Reis, Makler e Waga, Class. Quant. Grav. 22, 353 (2005), Erratum-ibid.22, 1191 (2005). = 0 = 0.1 = 0.2 = 0.3

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A NEW TYPE OF QUARTESSENCE L. Amendola, M. Makler, R. R. R. Reis e I. Waga, Phys. Rev. D 74, 063524 (2006).

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TYPE Ia SUPERNOVAE

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X-RAY CLUSTER GAS FRACTION

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CONSTRAINTS FROM SNeIa AND CLUSTERS

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CONSTRAINTS FROM MATTER (SDSS) AND CMB POWER SPECTRUM (WMAP1)

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COMBINED ANALYSIS: SNeIa + Clusters + SDSS + WMAP1

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ztzt

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We have on known manner of obtain quartessence models, distinct from CDM, in agreement with Large scale structure and CMB data: considering entropy perturbations; Observational constraints on the step-like model impose which implies that the transition has occurred at. The hypothesis of unifying dark matter cannot be ruled out with the present observational data. CONCLUSION

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TRABALHOS PUBLICADOS NA ÁREA R. R. R. Reis, Phys. Rev. D 67, 087301 (2003), Erratum-ibid. D 68, 089901 (2003). R. R. R. Reis, I. Waga, M. O. Calvão, and S. E. Jorás, Phys. Rev. D 68, 061302(R) (2003). R. R. R. Reis, M. Makler, and I. Waga, Phys. Rev. D 69, 101301(R) (2004). R. R. R. Reis, M. Makler and I. Waga, Class. Quant. Grav. 22, 353 (2005), Erratum- ibid. 22, 1191 (2005). L. Amendola, M. Makler, R. R. R. Reis and I. Waga, Phys. Rev. D 74, 063524 (2006).

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