Pole dark energy

Abstract

Theories with a pole in the kinetic term have been used to great effect in studying inflation, owing to their quantum stability and attractor properties. We explore the use of such pole kinetic terms in dark energy theories, finding an interesting link between thawing and freezing models, and the possibility of enhanced plateaus with "superattractor"-like behavior. We assess the observational viability of pole dark energy, showing that simple models can give dark energy equation of state evolution with w(z) < −0.9 even for potentials that could not normally achieve this easily. The kinetic term pole also offers an interesting perspective with respect to the swampland criteria for such observationally viable dark energy models.

Cosmic Birefringence from Monodromic Axion Dark Energy

“…The first equation is close to the results in [83] and the second relation is compatible with the results discussed in [84,86]. The reason why these formulas are precise for different powers of the potential is that the field never rolls for long, thus it cannot see the full shape of the potential 13 .…”

Dark energy model with very large-scale inhomogeneity

“…Many theoretical models of dark energy have been investigated [6,8], in which dynamical models are very interesting [11][12][13][14][15][16][17][18], because they are related to the field theory associated with the primordial high-energy epoch of the universe and fundamental theories of theoretical physics [6,7,19]. Particularly interesting ones are the dynamical models based on the quantum fluctuations of ultralight scalar fields [12][13][14][15][16][17][18], which reveal an interesting connection to the string axiverse scenario [20][21][22][23][24][25][26].…”

“…As in the ΛCDM model and in many models of dark energy, a basic assumption of their property is spatial isotropy and homogeneity, which follows the cosmological principle. Nevertheless, since the late-time expansion of the universe is dominated by dark energy, some interesting outcomes may occur to affect cosmological observables if large-scale inhomogeneities of dark energy arise, which could be tested by various cosmological observations [19,[27][28][29][30].…”

Dark Twilight Joined with the Light of Dawn to Unveil the Reionization History

“…Monotonic histories are represented by the single bin treatment named B1, that allows also for step like histories, and the minimal case with a single node with the constraint ṅion t rec = n H at z = a int that restricts reionization to a single burst. For Helium reionization we assume the default hyperbolic tangent provided by the Boltzmann code [55] (note however that the study of Helium reionization is in rapid development [56][57][58]).…”