相关论文: Varying alpha from N-body Simulations
We investigate the static and spherically symmetric solutions of Einstein's equations for a scalar field with non-canonical kinetic term, assumed to provide both the dark matter and dark energy components of the Universe. In particular, we…
We study analytically the intermediate and late-time behaviour of the massive scalar field in the background of static spherically symmetric brane black hole solutions. The intermediate behavoiur of the scalar field reveals the dependence…
We consider three cosmological models with non-power-law spectra of primordial density perturbations and test them against $\Lambda$CDM in density profiles of dark matter halos. We found that, despite the significant difference in initial…
We show that if the $\alpha$-attractor model is realized by the spontaneous breaking of the scale symmetry, then the stability and the dynamics of the vector field that gauges the scale symmetry can severely constrain the $\alpha$-parameter…
Aims: We study the dependence of the dynamical properties of dark matter halos on their environment in a whole-sky $\Lambda$CDM light-cone simulation extending to $z\sim 0.65$. The properties of interest are halo shape (parametrized by its…
We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias $b_1$ and $b_2$ on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed…
We study cosmological models involving scalar fields coupled to radiation and discuss their effect on the redshift evolution of the cosmic microwave background temperature, focusing on links with varying fundamental constants and dynamical…
We consider scalar dark matter models where the theory has a shift symmetry only broken by the scalar mass term. We restrict ourselves to K-essence kinetic terms where the shift symmetric part of the Lagrangian is a function of the first…
We study the linear instability and the nonlinear dynamical evolution of the Reissner-Nordstr\"om (RN) black hole in the Einstein-Maxwell-scalar theory in asymptotic flat spacetime. We focus on the coupling function $f(\phi)=e^{-b\phi^2}$…
I review recent constraints on and claimed detections of a time-varying fine-structure constant $\alpha$, and discuss our own work, particularly on the effects of $\alpha$ in the cosmic microwave background and large-scale structure. Our…
We study the cosmology of a general scalar field and barotropic fluid during the early stage of a brane-world where the Friedmann constraint is dominated by the square of the energy density. Assuming both the scalar field and fluid are…
We present a new simulation technique in which any chosen mode $\mathbf{k}$ of the density contrast field can be amplified by an amplitude $\Delta$. These amplified-mode simulations allow us to study the response of the halo density field…
In 1976, Shlyakhter showed that the Sm data from Oklo results in the upper bound on the time-variability of the fine-structure constant: $|\dot{\alpha}/\alpha| \lsim 10^{-17}{\rm y}^{-1}$, which has ever been the most stringent bound. Since…
We study the cosmological evolution of a nonflat Friedmann-Robertson-Walker Universe filled by pressureless dark matter and Barrow Holographic Dark Energy (BHDE). The latter is a dark energy model based on the holographic principle with…
We study the non-linear gravitational collapse of dark matter into halos through numerical N-body simulations of Lemaitre-Tolman-Bondi void models. We extend the halo mass function formalism to these models in a consistent way. This…
The nonlinear perturbation theory of gravitational instability is extended to include effects of both biasing and redshift-space distortions, which are inevitable in predicting observable quantities in galaxy surveys. The precise…
We consider the signatures of a domain wall produced in the spontaneous symmetry breaking involving a dilaton-like scalar field coupled to electromagnetism. Domains on either side of the wall exhibit slight differences in their respective…
We present nearly self-consistent stellar-halo models of the Fornax dwarf spheroidal galaxy associated with the Milky Way galaxy. Such galaxies are dominated by dark matter and have almost no gas in the system. Therefore, they are excellent…
There are indications from the study of quasar absorption spectra that the fine structure constant $\alpha$ may have been measurably smaller for redshifts $z>2.$ Analyses of other data ($^{149}$Sm fission rate for the Oklo natural reactor,…
Speculation that the fine-structure constant $\alpha$ varies in spacetime has a long history. We derive, in 4-D general relativity and in isotropic coordinates, the solution for a charged spherical black hole according to the framework for…