Phantom evolution in power-law potentials

Abstract

We investigate phantom models with power-law potentials and we extract the early-time, "tracker", solutions under the assumption of matter domination. Contrary to quintessence case, we find that energy positivity requires normal power-law potentials instead of inverse power-law ones, with the potential exponent being bounded by the quadratic form. In addition, we analytically present the general cosmological solution at intermediate times, that is at low redshifts, which is the period of the transition from matter to dark-energy domination. The comparison with the exact evolution, arising from numerical elaboration, shows that the tracker solution agrees with the later within 2% for redshifts z 1.5, while the intermediate solution is accurate within 2% up to z ≈ 0.5. PACS numbers: 95.36.+x,

Quintom cosmology: Theoretical implications and observations

“…This shows that for uncoupling and coupling exponential potentials the evolutions of our universe are very similar in the time interval we consider here. The lower figure is different from Fig.6 but has a common characteristic with the phantom with power-law potential [148], quintessence with inverse power-law potential and Chaplygin gas model [149] that it reaches the point of LCDM with the increasing of time. This is due to the fact that they all lead to the same fate of the universe-de Sitter expansion, but the trajectories to LCDM are different, therefore they can be differentiated.…”

“…Firstly we assume that there is no direct coupling between the phantom scalar field and the normal scalar field, that is we assume the simple exponential potentials of the previous subsection: V (σ, φ) = V σ 0 e −ασ + V φ 0 e −βφ , where α and β are constants. As we have shown, in this case the universe is moving towards the phantom dominated, late time attractor [81,82,137,148]. In Fig.6 it is depicted the time evolution of statefinder pair {r, s} in the time interval ∈ [0.…”

Phenomenological Fluids from Interacting Tachyonic Scalar Fields

“…Alternative models of dark energy suggest a dynamical form of dark energy, which at least in an effective level, can originate from a variable cosmological constant [24,25], or from various fields, such as a canonical scalar field [26][27][28][29][30] (quintessence), a phantom field [31][32][33][34][35][36][37][38] or the quintom [39][40][41][42][43][44][45][46][47][48][49][50][51]. By using some basic of quantum gravitational principles, we can formulate several other models for dark energy and in literature they are known as holographic dark energy paradigm [52][53][54][55][56][57][58][59][60][61][62][63] and agegraphic dark energy models [64][65][66].…”

Teleparallel quintessence with a nonminimal coupling to a boundary term

“…This can be achieved by adding to the matter sector a canonical scalar field [10][11][12][13][14][15][16][17][18][19][20][21][22][23], known as quintessence, a phantom scalar field [24][25][26][27][28][29], or a combination of both of these fields called quintom [30][31][32][33][34][35][36][37][38][39]. A review of these models can be found in [40,41].…”