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Register a new userDisentangling dark sector models using weak lensing statistics
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We perform multi-plane ray-tracing using the GLAMER gravitational lensing code within high-resolution light-cones extracted from the CoDECS simulations: a suite of cosmological runs featuring a coupling between Dark Energy and Cold Dark Matter. We show that the presence of the coupling is evident not only in the redshift evolution of the normalisation of the convergence power spectrum, but also in differences in non-linear structure formation with respect to {Lambda}CDM. Using a tomographic approach under the assumption of a {Lambda}CDM cosmology, we demonstrate that weak lensing measurements would result in a {sigma}8 value that changes with the source redshift if the true underlying cosmology is a coupled Dark Energy one. This provides a generic null test for these types of models. We also find that different models of coupled Dark Energy can show either an enhanced or a suppressed correlation between convergence maps with differing source redshifts as compared to {Lambda}CDM. This would provide a direct way to discriminate between different possible realisations of the coupled Dark Energy scenario. Finally, we discuss the impact of the coupling on several lensing observables for different source redshifts and angular scales with realistic source redshift distributions for current ground-based and future space-based lensing surveys.
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We forecast and optimize the cosmological power of various weak-lensing aperture mass ($M_{rm ap}$) map statistics for future cosmic shear surveys, including peaks, voids, and the full distribution of pixels (1D $M_{rm ap}$). These alternative methods probe the non-Gaussian regime of the matter distribution, adding complementary cosmological information to the classical two-point estimators. Based on the SLICS and cosmo-SLICS $N$-body simulations, we build Euclid-like mocks to explore the $S_8 - Omega_{rm m} - w_0$ parameter space. We develop a new tomographic formalism which exploits the cross-information between redshift slices (cross-$M_{rm ap}$) in addition to the information from individual slices (auto-$M_{rm ap}$) probed in the standard approach. Our auto-$M_{rm ap}$ forecast precision is in good agreement with the recent literature on weak-lensing peak statistics, and is improved by $sim 50$% when including cross-$M_{rm ap}$. It is further boosted by the use of 1D $M_{rm ap}$ that outperforms all other estimators, including the shear two-point correlation function ($gamma$-2PCF). When considering all tomographic terms, our uncertainty range on the structure growth parameter $S_8$ is enhanced by $sim 45$% (almost twice better) when combining 1D $M_{rm ap}$ and the $gamma$-2PCF compared to the $gamma$-2PCF alone. We additionally measure the first combined forecasts on the dark energy equation of state $w_0$, finding a factor of three reduction of the statistical error compared to the $gamma$-2PCF alone. This demonstrates that the complementary cosmological information explored by non-Gaussian $M_{rm ap}$ map statistics not only offers the potential to improve the constraints on the recent $sigma_8$ - $Omega_{rm m}$ tension, but also constitutes an avenue to understand the accelerated expansion of our Universe.
Upcoming weak-lensing surveys have the potential to become leading cosmological probes provided all systematic effects are under control. Recently, the ejection of gas due to feedback energy from active galactic nuclei (AGN) has been identified as major source of uncertainty, challenging the success of future weak-lensing probes in terms of cosmology. In this paper we investigate the effects of baryons on the number of weak-lensing peaks in the convergence field. Our analysis is based on full-sky convergence maps constructed via light-cones from $N$-body simulations, and we rely on the baryonic correction model of Schneider et al. (2019) to model the baryonic effects on the density field. As a result we find that the baryonic effects strongly depend on the Gaussian smoothing applied to the convergence map. For a DES-like survey setup, a smoothing of $theta_kgtrsim8$ arcmin is sufficient to keep the baryon signal below the expected statistical error. Smaller smoothing scales lead to a significant suppression of high peaks (with signal-to-noise above 2), while lower peaks are not affected. The situation is more severe for a Euclid-like setup, where a smoothing of $theta_kgtrsim16$ arcmin is required to keep the baryonic suppression signal below the statistical error. Smaller smoothing scales require a full modelling of baryonic effects since both low and high peaks are strongly affected by baryonic feedback.
We use the Equation of State (EoS) approach to study the evolution of the dark sector in Horndeski models, the most general scalar-tensor theories with second order equations of motion. By including the effects of the dark sector into our code EoS_class, we demonstrate the numerical stability of the formalism and excellent agreement with results from other publicly available codes for a range of parameters describing the evolution of the function characterising the perturbations for Horndeski models, $alpha_{rm x}$, with ${rm x}={{rm K}, {rm B}, {rm M}, {rm T}}$. After demonstrating that on sub-horizon scales ($kgtrsim 10^{-3}~{rm Mpc}^{-1}$ at $z=0$) velocity perturbations in both the matter and the dark sector are typically subdominant with respect to density perturbations in the equation of state for perturbations, we find an attractor solution for the dark sector gauge-invariant density perturbation $Delta_{rm ds}$ by neglecting its time derivatives in the equation describing its time evolution, as commonly done in the well-known quasi-static approximation. Using this result, we provide simplified expressions for the equation-of-state functions: the dark sector entropy perturbations $w_{rm ds}Gamma_{rm ds}$ and anisotropic stress $w_{rm ds}Pi_{rm ds}$. From this we derive a growth factor-like equation for both matter and dark sector and are able to capture the relevant physics for several observables with great accuracy. We finally present new analytical expressions for the well-known modified gravity phenomenological functions $mu$, $eta$ and $Sigma$ for a generic Horndeski model as functions of $alpha_{rm x}$. We show that on small scales they reproduce expressions presented in previous works, but on large scales, we find differences with respect to other works.
In this paper we constrain four alternative models to the late cosmic acceleration in the Universe: Chevallier-Polarski-Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell $1689$ are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SNIa), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained of the SL data are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak but they are similar to the BAO, SNIa and CMB estimations. We also compute the figure-of-merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modelling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters.
In this Letter, we report the observational constraints on the Hu-Sawicki $f(R)$ theory derived from weak lensing peak abundances, which are closely related to the mass function of massive halos. In comparison with studies using optical or x-ray clusters of galaxies, weak lensing peak analyses have the advantages of not relying on mass-baryonic observable calibrations. With observations from the Canada-France-Hawaii-Telescope Lensing Survey, our peak analyses give rise to a tight constraint on the model parameter $|f_{R0}|$ for $n=1$. The $95%$ CL limit is $log_{10}|f_{R0}| < -4.82$ given WMAP9 priors on $(Omega_{rm m}, A_{rm s})$. With Planck15 priors, the corresponding result is $log_{10}|f_{R0}| < -5.16$.
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