Anisotropic dark energy: dynamics of the background and perturbations

By Tomi Koivisto, D. Mota. 2008

177 citations recorded by the source corpus.

We investigate cosmologies where the accelerated expansion of the universe is driven by a field with an anisotropic equation of state. We model such scenarios within the Bianchi I framework, introducing two skewness parameters to quantify the deviation of pressure from isotropy. We study the dynamics of the background expansion in these models. A special case of an anisotropic cosmological constant is analyzed in detail. The anisotropic expansion is then confronted with the redshift and angular distribution of the type Ia supernovae. In addition, we investigate the effects on the cosmic microwave background (CMB) anisotropies for which the main signature appears to be a quadrupole contribution. We find that the two skewness parameters can be very well constrained. Tightest bounds are imposed by the CMB quadrupole, but there are anisotropic models which avoid these bounds completely. Within these bounds, the anisotropy can be beneficial as a potential explanation for various anomalous cosmological observations, especially in the CMB at the largest angles. We also consider the dynamics of linear perturbations in these models. The covariant approach is used to derive the general evolution equations for cosmological perturbations, taking into account imperfect sources in an anisotropic background. The implications for galaxy formation are then studied. These results might help to make contact between the observed anomalies in CMB and large-scale structure and fundamental theories exhibiting Lorentz violation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/ca740a4dbd23274e2be7c14f3ae5dbce6471a1b0

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Citations in the corpus

Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “These difficulties vanish if an anisotropic expansion takes place only well after the decoupling between matter and radiation, for example at the time of dark energy domination [692, 691, 143, 311, 338].”
Probing the anisotropic local Universe and beyond with SNe Ia data (2010, background): “…of the Universe (Kolatt & Lahav 2001; Bonvin, Durrer & Kunz 2006; Gordon, Land & Slosar 2007; Schwarz & Weinhorst 2007; Gupta, Saini & Laskar 2008; Koivisto & Mota 2008a,b; Blomqvist, Enander & Mortsell 2008; Cooray, Holz & Caldwell 2010; Gupta & Saini 2010; Koivisto et al. 2011) and to determine…”
Imperfect Dark Energy from Kinetic Gravity Braiding (2010, background): “gy Condition. Other authors have also considered phenomenological models of dark energy which include deviations of the energy-momentum tensor away from the perfectuid form such as anisotropic stress [92, 93, 94]. 5.1 Phase Space The phase-space plot for ˚_ for an FRW cosmology, extended to show Jan”