Spatially homogeneous universes with late-time anisotropy
Classical and Quantum Gravity IOP Publishing 40:24 (2023) 245015
Abstract:
The cosmological principle asserts that on sufficiently large scales the Universe is homogeneous and isotropic on spatial slices. To deviate from this principle requires a departure from the FLRW ansatz. In this paper we analyze the cosmological evolution of two spatially homogeneous but anisotropic universes, namely the spatially closed Kantowski–Sachs Universe and the open axisymmetric Bianchi type III Universe. These models are characterized by two scale factors and we study their evolution in universes with radiation, matter and a cosmological constant. In all cases, the two scale factors evolve differently and this anisotropy leads to a lensing effect in the propagation of light. We derive explicit formulae for computing redshifts, angular diameter distances and luminosity distances and discuss the predictions of these models in relation to observations for type Ia supernovae and the CMB. We comment on the possibility of explaining the observed luminosity distance plot for type Ia supernovae within the context of cosmologies featuring late-time anisotropy and a vanishing cosmological constant.Underdetermination of dark energy
Physical Review D American Physical Society 108:10 (2023) 103519
Abstract:
There is compelling evidence that the Universe is undergoing a late phase of accelerated expansion. One of the simplest explanations for this behavior is the presence of dark energy. A plethora of microphysical models for dark energy have been proposed. The hope is that, with the ever increasing precision of cosmological surveys, it will be possible to precisely pin down the model. We show that this is unlikely and that, at best, we will have a phenomenological description for the microphysics of dark energy. Furthermore, we argue that the current phenomenological prescriptions are ill-equipped for shedding light on the fundamental theory of dark energy.Extragalactic Magnetism with SOFIA (SALSA Legacy Program). VII. A tomographic view of far infrared and radio polarimetric observations through MHD simulations of galaxies
(2023)
FRB 20210405I: a nearby Fast Radio Burst localized to sub-arcsecond precision with MeerKAT
Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 527:2 (2023) 3659-3673
Constraining cosmology with the Gaia-unWISE Quasar Catalog and CMB lensing: structure growth
Journal of Cosmology and Astroparticle Physics IOP Publishing 2023:11 (2023) 43