scholarly journals The impact of mass map truncation on strong lensing simulations

2020 ◽  
Vol 644 ◽  
pp. A108
Author(s):  
Lyne Van de Vyvere ◽  
Dominique Sluse ◽  
Sampath Mukherjee ◽  
Dandan Xu ◽  
Simon Birrer
Keyword(s):  
Galaxy Evolution ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Cosmological Parameters ◽  
Strong Gravitational Lensing ◽  
Strong Lensing ◽  
Dynamical Simulations ◽  
The Impact ◽  
Einstein Radius ◽  
Specific Impact

Strong gravitational lensing is a powerful tool to measure cosmological parameters and to study galaxy evolution mechanisms. However, quantitative strong lensing studies often require mock observations. To capture the full complexity of galaxies, the lensing galaxy is often drawn from high resolution, dark matter only or hydro-dynamical simulations. These have their own limitations, but the way we use them to emulate mock lensed systems may also introduce significant artefacts. In this work we identify and explore the specific impact of mass truncation on simulations of strong lenses by applying different truncation schemes to a fiducial density profile with conformal isodensity contours. Our main finding is that improper mass truncation can introduce undesired artificial shear. The amplitude of the spurious shear depends on the shape and size of the truncation area as well as on the slope and ellipticity of the lens density profile. Due to this effect, the value of H0 or the shear amplitude inferred by modelling those systems may be biased by several percents. However, we show that the effect becomes negligible provided that the lens projected map extends over at least 50 times the Einstein radius.

scholarly journals Testing dark energy models with a new sample of strong-lensing systems

2020 ◽  
Vol 498 (4) ◽  
pp. 6013-6033
Author(s):  
Mario H Amante ◽  
Juan Magaña ◽  
V Motta ◽  
Miguel A García-Aspeitia ◽  
Tomás Verdugo
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
Velocity Dispersion ◽  
Cosmological Parameters ◽  
Cosmic Acceleration ◽  
Dark Matter Halo ◽  
Measured Velocity ◽  
Strong Lensing ◽  
The Impact ◽  
Einstein Radius

ABSTRACT Inspired by a new compilation of strong-lensing systems, which consist of 204 points in the redshift range 0.0625 < zl < 0.958 for the lens and 0.196 < zs < 3.595 for the source, we constrain three models that generate a late cosmic acceleration: the ω-cold dark matter model, the Chevallier–Polarski–Linder, and the Jassal–Bagla–Padmanabhan parametrizations. Our compilation contains only those systems with early-type galaxies acting as lenses, with spectroscopically measured stellar velocity dispersions, estimated Einstein radius, and both the lens and source redshifts. We assume an axially symmetric mass distribution in the lens equation, using a correction to alleviate differences between the measured velocity dispersion (σ) and the dark matter halo velocity dispersion (σDM) as well as other systematic errors that may affect the measurements. We have considered different subsamples to constrain the cosmological parameters of each model. Additionally, we generate a mock data of SLS to asses the impact of the chosen mass profile on the accuracy of Einstein radius estimation. Our results show that cosmological constraints are very sensitive to the selected data: Some cases show convergence problems in the estimation of cosmological parameters (e.g. systems with observed distance ratio Dobs < 0.5), others show high values for the χ2 function (e.g. systems with a lens equation Dobs > 1 or high velocity dispersion σ > 276 km s−1). However, we obtained a fiduciary sample with 143 systems, which improves the constraints on each tested cosmological model.

Strong Gravitational Lensing Time Delay Statistics and the Density Profile of Dark Halos

2002 ◽  
Vol 568 (2) ◽  
pp. 488-499 ◽  
Author(s):  
Masamune Oguri ◽  
Atsushi Taruya ◽  
Yasushi Suto ◽  
Edwin L. Turner
Keyword(s):  
Time Delay ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Strong Gravitational Lensing

scholarly journals The impact of AGN feedback on galaxy intrinsic alignments in the Horizon simulations

2020 ◽  
Vol 492 (3) ◽  
pp. 4268-4282 ◽  
Author(s):  
Adam Soussana ◽  
Nora Elisa Chisari ◽  
Sandrine Codis ◽  
Ricarda S Beckmann ◽  
Yohan Dubois ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Gravitational Lensing ◽  
Large Scale ◽  
Galactic Nuclei ◽  
Three Dimensions ◽  
High Mass ◽  
Angular Momenta ◽  
The Galaxy ◽  
The Impact ◽  
The Universe

ABSTRACT The intrinsic correlations of galaxy shapes and orientations across the large-scale structure of the Universe are a known contaminant to weak gravitational lensing. They are known to be dependent on galaxy properties, such as their mass and morphologies. The complex interplay between alignments and the physical processes that drive galaxy evolution remains vastly unexplored. We assess the sensitivity of intrinsic alignments (shapes and angular momenta) to active galactic nuclei (AGN) feedback by comparing galaxy alignment in twin runs of the cosmological hydrodynamical Horizon simulation, which do and do not include AGN feedback, respectively. We measure intrinsic alignments in three dimensions and in projection at $z$ = 0 and $z$ = 1. We find that the projected alignment signal of all galaxies with resolved shapes with respect to the density field in the simulation is robust to AGN feedback, thus giving similar predictions for contamination to weak lensing. The relative alignment of galaxy shapes around galaxy positions is however significantly impacted, especially when considering high-mass ellipsoids. Using a sample of galaxy ‘twins’ across simulations, we determine that AGN changes both the galaxy selection and their actual alignments. Finally, we measure the alignments of angular momenta of galaxies with their nearest filament. Overall, these are more significant in the presence of AGN as a result of the higher abundance of massive pressure-supported galaxies.

scholarly journals Assessing the effect of lens mass model in cosmological application with updated galaxy-scale strong gravitational lensing sample

2019 ◽  
Vol 488 (3) ◽  
pp. 3745-3758 ◽  
Author(s):  
Yun Chen ◽  
Ran Li ◽  
Yiping Shu ◽  
Xiaoyue Cao
Keyword(s):  
Density Profile ◽  
Gravitational Lensing ◽  
Mass Density ◽  
Cosmological Parameters ◽  
Mass Model ◽  
Surface Mass ◽  
Cosmological Application ◽  
Surface Mass Density ◽  
Resolution Imaging ◽  
Lens Galaxies

ABSTRACT By comparing the dynamical and lensing masses of early-type lens galaxies, one can constrain both the cosmological parameters and the density profiles of galaxies. We explore the constraining power on cosmological parameters and the effect of the lens mass model in this method with 161 galaxy-scale strong lensing systems, which is currently the largest sample with both high-resolution imaging and stellar dynamical data. We assume a power-law mass model for the lenses, and consider three different parametrizations for γ (i.e. the slope of the total mass density profile) to include the effect of the dependence of γ on redshift and surface mass density. When treating δ (i.e. the slope of the luminosity density profile) as a universal parameter for all lens galaxies, we find the limits on the cosmological parameter Ωm are quite weak and biased, and also heavily dependent on the lens mass model in the scenarios of parametrizing γ with three different forms. When treating δ as an observable for each lens, the unbiased estimate of Ωm can be obtained only in the scenario of including the dependence of γ on both the redshift and the surface mass density, that is $\Omega _\mathrm{ m} = 0.381^{+0.185}_{-0.154}$ at 68 per cent confidence level in the framework of a flat ΛCDM model. We conclude that the significant dependencies of γ on both the redshift and the surface mass density, as well as the intrinsic scatter of δ among the lenses, need to be properly taken into account in this method.

scholarly journals CONSTRAINTS ON COSMIC EQUATION OF STATE USING GRAVITATIONAL LENSING STATISTICS WITH EVOLVING GALAXIES

2003 ◽  
Vol 12 (01) ◽  
pp. 101-119 ◽  
Author(s):  
ABHA DEV ◽  
DEEPAK JAIN ◽  
N. PANCHAPAKESAN ◽  
S. MAHAJAN ◽  
V. B. BHATIA
Keyword(s):  
Equation Of State ◽  
Galaxy Evolution ◽  
Gravitational Lensing ◽  
Entire Range ◽  
Cosmological Parameters ◽  
Observational Constraints ◽  
Number Density ◽  
Cosmological Observations ◽  
Likelihood Analysis ◽  
Luminosity Evolution

In this paper, observational constraints on the cosmic equation of state of dark energy (p = wρ) have been investigated using gravitational lensing statistics. A likelihood analysis of the lens survey has been carried out to constrain the cosmological parameters Ωmand w. Constraints on Ωmand w are obtained in three different models of galaxy evolution: no evolution model (comoving number density of galaxies remain constant), Volmerange and Guiderdoni Model and fast merging model. The last two models consider the number evolution of galaxies in addition to the luminosity evolution. The likelihood analysis shows that for the no-evolution case w ≤ -0.04 and Ωm≤ 0.90 at 1σ (68% confidence level (CL)). Similarly for the Volmerange & Guiderdoni Model the constraints are w ≤ -0.04 and Ωm≤ 0.91 at 1σ. In fast merging model the constraint become weaker and it allows almost the entire range of parameters. For the case of constant Λ (w = -1), all the models permit Ωm= 0.3 with 68% CL, which is consistent with the value of Ωminferred from various other cosmological observations.

scholarly journals Covariance matrices for galaxy cluster weak lensing: from virial regime to uncorrelated large-scale structure

2019 ◽  
Vol 490 (2) ◽  
pp. 2606-2626 ◽  
Author(s):  
Hao-Yi Wu ◽  
David H Weinberg ◽  
Andrés N Salcedo ◽  
Benjamin D Wibking ◽  
Ying Zu
Keyword(s):  
Gravitational Lensing ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Galaxy Cluster ◽  
Covariance Matrices ◽  
Density Fluctuations ◽  
Cosmic Acceleration ◽  
Weak Lensing ◽  
Wide Range ◽  
The Impact

ABSTRACT Next-generation optical imaging surveys will revolutionize the observations of weak gravitational lensing by galaxy clusters and provide stringent constraints on growth of structure and cosmic acceleration. In these experiments, accurate modelling of covariance matrices of cluster weak lensing plays the key role in obtaining robust measurements of the mean mass of clusters and cosmological parameters. We use a combination of analytical calculations and high-resolution N-body simulations to derive accurate covariance matrices that span from the virial regime to linear scales of the cluster-matter cross-correlation. We validate this calculation using a public ray-tracing lensing simulation and provide a software package for calculating covariance matrices for a wide range of cluster and source sample choices. We discuss the relative importance of shape noise and density fluctuations, the impact of radial bin size, and the impact of off-diagonal elements. For a weak lensing source density ns = 10 arcmin−2, shape noise typically dominates the variance on comoving scales $r_{\rm p}\lesssim 5\ h^{-1} \, \rm Mpc$. However, for ns = 60 arcmin−2, potentially achievable with future weak lensing experiments, density fluctuations typically dominate the variance at $r_{\rm p}\gtrsim 1\ h^{-1} \, \rm Mpc$ and remain comparable to shape noise on smaller scales.

scholarly journals Dark-Matter in Galaxies from Gravitational Lensing and Stellar Dynamics Studies

2009 ◽  
Vol 5 (H15) ◽  
pp. 74-74
Author(s):  
L. V. E. Koopmans
Keyword(s):  
Dark Matter ◽  
Mass Distribution ◽  
Density Profile ◽  
Gravitational Lensing ◽  
Total Mass ◽  
Stellar Dynamics ◽  
Early Type ◽  
Complementary Methods ◽  
Strong Gravitational Lensing

AbstractStrong gravitational lensing and stellar dynamics provide two complementary methods in the study of the mass distribution of dark matter in galaxies out to redshift of unity. They are particularly powerful in the determination of the total mass and the density profile of mass early-type galaxies on kpc to tens of kpc scales, and also reveal the presence of mass-substructure on sub-kpc scale. I will shortly discuss these topics in this review.

scholarly journals STRONG GRAVITATIONAL LENSING AND ITS COSMIC CONSTRAINTS

2013 ◽  
Vol 28 (14) ◽  
pp. 1350057 ◽  
Author(s):  
NANNAN WANG ◽  
LIXIN XU
Keyword(s):  
Cosmological Model ◽  
Gravitational Lensing ◽  
Velocity Dispersion ◽  
Model Space ◽  
Data Sets ◽  
Spatial Curvature ◽  
Strong Gravitational Lensing ◽  
Strong Lensing ◽  
Λcdm Model ◽  
Stellar Velocity

In this paper, we propose a new method to use the strong lensing data sets to constrain a cosmological model. By taking the ratio [Formula: see text] as cosmic observations, one can completely eliminate the uncertainty caused by the relation σSIS= fEσ0which characterizes the relation between the stellar velocity dispersion σ0and the velocity dispersion σSIS. Via our method, a relative tight constraint to the cosmological model space can be obtained, for the spatially flat ΛCDM model as an example [Formula: see text] in 3σ regions. And by using this method, one can also probe the nature of dark energy and the spatial curvature of our Universe.

scholarly journals Simulating Groups and the IntraGroup Medium: The Surprisingly Complex and Rich Middle Ground between Clusters and Galaxies

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 209
Author(s):  
Benjamin D. Oppenheimer ◽  
Arif Babul ◽  
Yannick Bahé ◽  
Iryna S. Butsky ◽  
Ian G. McCarthy
Keyword(s):  
Galaxy Evolution ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Cosmic Ray ◽  
Cosmological Simulations ◽  
Hydrodynamic Simulations ◽  
Galaxy Groups ◽  
Cooling Flows ◽  
Multi Phase ◽  
The Impact

Galaxy groups are more than an intermediate scale between clusters and halos hosting individual galaxies, they are crucial laboratories capable of testing a range of astrophysics from how galaxies form and evolve to large scale structure (LSS) statistics for cosmology. Cosmological hydrodynamic simulations of groups on various scales offer an unparalleled testing ground for astrophysical theories. Widely used cosmological simulations with ∼(100 Mpc)3 volumes contain statistical samples of groups that provide important tests of galaxy evolution influenced by environmental processes. Larger volumes capable of reproducing LSS while following the redistribution of baryons by cooling and feedback are the essential tools necessary to constrain cosmological parameters. Higher resolution simulations can currently model satellite interactions, the processing of cool (T≈104−5 K) multi-phase gas, and non-thermal physics including turbulence, magnetic fields and cosmic ray transport. We review simulation results regarding the gas and stellar contents of groups, cooling flows and the relation to the central galaxy, the formation and processing of multi-phase gas, satellite interactions with the intragroup medium, and the impact of groups for cosmological parameter estimation. Cosmological simulations provide evolutionarily consistent predictions of these observationally difficult-to-define objects, and have untapped potential to accurately model their gaseous, stellar and dark matter distributions.

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