arXiv subjects

Rui An

Publications and source records attributed to Rui An.

45 records · Page 3Linked to original sources

arXiv2019

Testing a quintessence model with Yukawa interaction from cosmological observations and N-body simulations

We consider a quintessence model with Yukawa interaction between dark energy and dark matter and constrain this model by employing the recent cosmological data including the updated cosmic microwave background (CMB) measurements from Planck 2015, the weak gravitational lensing measurements from Kilo Degree Survey (KiDS) and redshift-space distortions. We find that an interaction in the dark sector is compatible with observations. The updated Planck data can significantly improve the constraints compared with the previous results from Planck 2013, while the KiDS data has less constraining power than Planck. The Yukawa interaction model is found to be moderately favored by Planck and able to alleviate the discordance between weak lensing measurements and CMB measurements as previously inferred from the standard Lambda cold dark matter model. N-body simulations for Yukawa interaction model is also performed. We find that using the halo density profile is plausible to improve the constraints significantly in the future.

astro-ph.CO↗

arXiv2019

The first constraint from SDSS galaxy-galaxy weak lensing measurements on interacting dark energy models

We combine constraints from linear and nonlinear scales, for the first time, to study the interaction between dark matter and dark energy. We devise a novel N-body simulation pipeline for cosmological models beyond $Λ$CDM. This pipeline is fully self-consistent and opens a new window to study the nonlinear structure formation in general phenomenological interacting dark energy models. By comparing our simulation results with the SDSS galaxy-galaxy weak lensing measurements, we are able to constrain the strength of interaction between dark energy and dark matter. Compared with the previous studies using linear examinations, we point to plausible improvements on the constraints of interaction strength by using small scale information from weak lensing. This improvement is mostly due to the sensitivity of weak lensing measurements on nonlinear structure formation at low redshift. With this new pipeline, it is possible to look for smoking gun signatures of dark matter-dark energy interaction.

astro-ph.CO↗

arXiv2019

Signature of the interaction between dark sectors in the reionization process

We consider the reionization process in a cosmological model in which dark matter interacts with dark energy. Using a semi-analytical reionization model, we compute the evolution of the ionized fraction in terms of its spatial average and linear perturbations. We show that certain types of interactions between dark matter and dark energy can significantly affect the reionization history. We calculate the 21 cm signals in the interaction models, and compare the results with the predictions of the ${\rm ΛCDM}$ model.

astro-ph.CO↗

arXiv2019

Can Conformal and Disformal Couplings Between Dark Sectors Explain the EDGES 21cm Anomaly?

The recently announced result by EDGES points an unexpected excess in the 21 cm global brightness temperature from cosmic dawn at $z\sim 17$, potentially indicating new phenomena beyond the $Λ$CDM model. A generic cosmological model which allows conformal and disformal couplings between dark matter and dark energy is employed to investigate the impact on the 21cm absorption signal and understand the EDGES anomaly. After exploring a wide range of parameter space for couplings, we find that the coupling effects can lead to a moderate change in the Hubble parameter while a negligible change in the spin temperature in the early Universe. Consequently, the decrease of the Hubble parameter from the mixed conformal and disformal couplings can reproduce the 21cm absorption approximately in consistent with the EDGES result at $z=17.5$. However, there is still tension in corresponding parameter space between EDGES and other cosmological observations for this model.

astro-ph.CO↗

arXiv2018

A Fully Self-Consistent Cosmological Simulation Pipeline for Interacting Dark Energy Models

We devise a fully self-consistent simulation pipeline for the first time to study the interaction between dark matter and dark energy. We perform convergence tests and show that our code is accurate on different scales. Using the parameters constrained by Planck, Type Ia Supernovae, Baryon Acoustic Oscillations (BAO) and Hubble constant observations, we perform cosmological N-body simulations. We calculate the resulting matter power spectra and halo mass functions for four different interacting dark energy models. In addition to the dark matter density distribution, we also show the inhomogeneous density distribution of dark energy. With this new simulation pipeline, we can further refine and constrain interacting dark energy models.

astro-ph.CO↗

arXiv2018

Stephani Cosmology: Entropically Viable But Observationally Challenged

Inhomogeneous cosmological models such as the Stephani universes could, in principle, provide an explanation for the observed accelerated expansion of the Universe. Working with a concrete, popular model of the Stephani cosmology -- the Stephani-Dabrowski model, we found that it is entropically viable. We also comment on the energy conditions and the two-sheeted geometry of the spacetime. However, similar to the LTB models, despite satisfying the holographic principle, Stephani cosmology has difficulty satisfying all the constraints from observations.

gr-qc↗

arXiv2018

Relieving the Tension between Weak Lensing and Cosmic Microwave Background with Interacting Dark Matter and Dark Energy Models

We constrain interacting dark matter and dark energy (IDMDE) models using a 450-degree-square cosmic shear data from the Kilo Degree Survey (KiDS) and the angular power spectra from Planck's latest cosmic microwave background measurements. We revisit the discordance problem in the standard Lambda cold dark matter ($Λ$CDM) model between weak lensing and Planck datasets and extend the discussion by introducing interacting dark sectors. The IDMDE models are found to be able to alleviate the discordance between KiDS and Planck as previously inferred from the $Λ$CDM model, and moderately favored by a combination of the two datasets.

astro-ph.CO↗

arXiv2017

Constraints on the dark matter and dark energy interactions from weak lensing bispectrum tomography

We estimate uncertainties of cosmological parameters for phenomenological interacting dark energy models using weak lensing convergence power spectrum and bispectrum. We focus on the bispectrum tomography and examine how well the weak lensing bispectrum with tomography can constrain the interactions between dark sectors, as well as other cosmological parameters. Employing the Fisher matrix analysis, we forecast parameter uncertainties derived from weak lensing bispectra with a two-bin tomography and place upper bounds on strength of the interactions between the dark sectors. The cosmic shear will be measured from upcoming weak lensing surveys with high sensitivity, thus it enables us to use the higher order correlation functions of weak lensing to constrain the interaction between dark sectors and will potentially provide more stringent results with other observations combined.

astro-ph.CO↗

arXiv2016

Dynamical analysis of modified gravity with nonminimal gravitational coupling to matter

We perform a phase space analysis of a generalized modified gravity theory with nonminimally coupling between geometry and matter. We apply the dynamical system approach to this generalized model and find that in the cosmological context, different choices of Lagrangian density will apparently result in different phases of the Universe. By carefully choosing the variables, we prove that there is an attractor solution to describe the late time accelerating universe when the modified gravity is chosen in a simple power-law form of the curvature scalar. We further examine the temperature evolution based on the thermodynamic understanding of the model. Confronting the model with supernova type Ia data sets, we find that the nonminimally coupled theory of gravity is a viable model to describe the late time Universe acceleration.

gr-qc↗