Constraining scalar field dark energy with cosmological observations

Abstract

High precision cosmological observations in last decade suggest that about 70% of our universe's energy density is in so called "Dark Energy" (DE). Observations show that DE has negative effective pressure and therefore unlike conventional energy sources accelerates the cosmic expansion instead of decelerating it. DE is highly uniform and has become a dominant component only recently. The simplest candidate for DE is the time-independent cosmological constant $\Lambda$. Although successful in fitting available data, the cosmological constant model has a number of theoretical shortcomings and because of that alternative models of DE are considered. In one such scenario a cosmological scalar field that slowly rolls down its potential acts like a time-dependent cosmological constant. I have used different independent cosmological data sets to constrain the time dependence of DE's energy density in the framework of the slowly-rolling cosmological scalar field model. Present data favors a time-independent cosmological constant, but the time-dependent DE can not be ruled out at high confidence level. Ongoing and planned cosmological probes and surveys will provide more and better quality data over the next decade. When the new data sets are available we will be able to either detect the time dependence of DE or constrain it to a very small physically uninteresting value.

PhD thesis

References in corpus (15)

• f(R) Theories Of Gravity
• Clustering of Luminous Red Galaxies IV: Baryon Acoustic Peak in the Line-of-Sight Direction and a Direct Measurement of H(z)
• The Anthropic Landscape of String Theory
• Consistently Large Cosmic Flows on Scales of 100 Mpc/h: a Challenge for the Standard LCDM Cosmology
• LBDS 53W091: An Old red Galaxy at z=1.552
• A measurement of large-scale peculiar velocities of clusters of galaxies: results and cosmological implications
• A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram
• Cosmic flow from 2MASS redshift survey: The origin of CMB dipole and implications for LCDM cosmology
• Gamma-Ray Bursts in $1.8<z<5.6$ Suggest that the Time Variation of the Dark Energy is Small
• Cosmography by GRBs
• First Cosmological Constraints on Dark Energy from the Radial Baryon Acoustic Scale
• Constraints on dark energy from the lookback time versus redshift test
• Galaxy Cluster Gas Mass Fraction and Hubble Parameter versus Redshift Constraints on Dark Energy
• Constraints on dark energy models from radial baryon acoustic scale measurements
• Current lookback time-redshift bounds on dark energy

Cited by in corpus (6)

• First evidence of running cosmic vacuum: challenging the concordance model
• Determining the Hubble constant from Hubble parameter measurements
• Growth Rate in the Dynamical Dark Energy Models
• Time and distance constraints on accelerating cosmological models
• Implications of Dynamical Dark Energy in the expansion of the Universe and the Structure Formation
• Estimations of the cosmological parameters from the observational variation of the fine structure constant