IS IT POSSIBLE TO OBSERVATIONALLY DISTINGUISH ADIABATIC
QUARTESSENCE FROM CDM?
Luca Amendola1, Martin Makler2, Ribamar R. R. Reis3 and Ioav Waga3 1 INAF/Osservatorio Astronomico di Roma,
2 Centro Brasileiro de Pesquisas Físicas,3 Instituto de Física – Universidade Federal do Rio de Janeiro
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.
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?
UNIFYING DARK MATTER OR QUARTESSENCE
A prototype – the generalized Chaplygin Gas.
• Chaplygin Gas (=1) – initially suggested as an alternative to quintessenceKamenshchik et al. PLB 511, 265 (2001).• Motivation: D-Branes.
Dark matter regime Dark energy regime
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
BACKGROUND DEPENDENT OBSERVATIONAL CONSTRAINTS
Makler, Quinet & Waga PRD 68,123521, 2003
SNeIa + Clusters + Radio-galaxies + weak lensing
PROBLEMS – LINEAR PERTURBATIONS
Sandvik, Tegmark, Zaldarriaga e Waga, Phys. Rev. D 69, 123524 (2004).Beça et al.- PRD 67,101301,2003Reis, 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
PERTURBATION THEORY IN COSMOLOGY
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.
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)
L. Amendola, I. Waga e F. Finelli, JCAP 11, 009 (2005)
CHAPLYGIN
OTHER CASES
Reis, Makler e Waga, Class. Quant. Grav. 22, 353 (2005) , Erratum-ibid.22, 1191 (2005).
= 0
= 0.1
= 0.2
= 0.3
OTHER CASES
Reis, Makler e Waga, Class. Quant. Grav. 22, 353 (2005) , Erratum-ibid.22, 1191 (2005).
= 0
= 0.1
= 0.2
= 0.3
A NEW TYPE OF QUARTESSENCEL. Amendola, M. Makler, R. R. R. Reis e I. Waga, Phys. Rev. D 74, 063524 (2006).
TYPE Ia SUPERNOVAE
X-RAY CLUSTER GAS FRACTION
CONSTRAINTS FROM SNeIa AND CLUSTERS
CONSTRAINTS FROM MATTER (SDSS)AND CMB POWER SPECTRUM (WMAP1)
COMBINED ANALYSIS: SNeIa + Clusters + SDSS + WMAP1
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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