arXiv subjects

Eric Jullo

Publications and source records attributed to Eric Jullo.

At least 37 records · Page 2Linked to original sources

arXiv2022

Dark Matter in Galaxy Clusters: a Parametric Strong Lensing Approach

We present a parametric strong lensing analysis of three massive clusters. Our aim is to probe the inner shape of dark matter haloes, in particular the existence of a core. We adopt the following working hypothesis: any group/cluster scale dark matter clump introduced in the modelling should be associated with a luminous counterpart. We also adopt some additional well motivated priors in the analysis, even if this degrades the quality of the fit, quantified using the RMS between the observed and model generated images. In particular, in order to alleviate the degeneracy between the smooth underlying component and the galaxy scale perturbers, we use the results from spectroscopic campaigns by Bergamini et al. (2019) allowing to fix the mass of the galaxy scale component. In the unimodal galaxy cluster AS1063, a cored mass model is favored with respect to a non cored mass model, and this is also the case in the multimodal cluster MACSJ0416. In the unimodal cluster MACSJ1206, we fail to reproduce the strong lensing constraints using a parametric approach within the adopted working hypothesis. We then successfully add a mild perturbation in the form of a superposition of B-spline potentials which allows to get a decent fit (RMS=0.5"), finally finding that a cored mass model is favored. Overall, our analysis suggest evidence for cored cluster scale dark matter haloes. These findings may be useful to interpret within alternative dark matter scenario, as self interacting dark matter. We propose a working hypothesis for parametric strong lensing modelling where the quest for the best fit model will be balanced by the quest for presenting a physically motivated mass model, in particular by imposing priors.

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arXiv2022

The Completed SDSS-IV Extended Baryon Oscillation Spectroscopic Survey: Growth rate of structure measurement from cosmic voids

We present a void clustering analysis in configuration-space using the completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 samples. These samples consist of Luminous Red Galaxies (LRG) combined with the high redshift tail of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) DR12 CMASS galaxies (called as LRG+CMASS sample), Emission Line Galaxies (ELG) and quasars (QSO). We build void catalogues from the three eBOSS DR16 samples using a ZOBOV-based algorithm, providing 2,814 voids, 1,801 voids and 4,347 voids in the LRG+CMASS, ELG and QSO samples, respectively, spanning the redshift range $0.6<z<2.2$. We measure the redshift space distortions (RSD) around voids using the anisotropic void-galaxy cross-correlation function and we extract the distortion parameter $β$. We test the methodology on realistic simulations before applying it to the data, and we investigate all our systematic errors on these mocks. We find $β^{\rm LRG}(z=0.74)=0.415\pm0.087$, $β^{\rm ELG}(z=0.85)=0.665\pm0.125$ and $β^{\rm QSO}(z=1.48)=0.313\pm0.134$, for the LRG+CMASS, ELG and QSO sample, respectively. The quoted errors include systematic and statistical contributions. In order to convert our measurements in terms of the growth rate $fσ_8$, we use consensus values of linear bias from the eBOSS DR16 companion papers~\citep{eBOSScosmo}, resulting in the following constraints: $fσ_8(z=0.74)=0.50\pm0.11$, $fσ_8(z=0.85)=0.52\pm0.10$ and $fσ_8(z=1.48)=0.30\pm0.13$. Our measurements are consistent with other measurements from eBOSS DR16 using conventional clustering techniques.

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arXiv2022

Scatter in the satellite galaxy SHMR: fitting functions, scaling relations & physical processes from the IllustrisTNG simulation

The connection between galaxies and their dark matter haloes is often described with the Stellar-to-Halo Mass relation (SHMR). Satellite galaxies in clusters have been shown to follow a SHMR distinct from central galaxies because of the environmental processes that they are subject to. In addition, the variety of accretion histories leads to an important scatter in this relation, even more for satellites than for central galaxies. In this work, we use the hydrodynamical simulation IllustrisTNG to study the scatter in the satellite galaxy SHMR, and extract the parameters that can best allow to understand it. Active galaxies, that represent a very small fraction of cluster galaxies, follow a very different relation than their passive counterparts, mainly because they were accreted much more recently. For this latter population, we find that the distance to the cluster centre is a good predictor of variations in the SHMR, but some information on the galaxy orbital history, such as the distance of closest approach to the host centre, is an even better one, although it is in practice more difficult to measure. In addition, we found that galaxy compactness is also correlated with the SHMR, while the host cluster properties (mass and concentration, formation redshift, mass and size of BCG) do not play a significant role. We provide accurate fitting functions and scaling relations to the scientific community, useful to predict the subhalo mass given a set of observable parameters. Finally, we connect the scatter in the SHMR to the physical processes affecting galaxies in clusters, and how they impact the different satellite sub-populations.

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arXiv2022

AMICO galaxy clusters in KiDS-DR3: Measurement of the halo bias and power spectrum normalization from a stacked weak lensing analysis

Galaxy clusters are biased tracers of the underlying matter density field. At very large radii beyond about 10 Mpc/\textit{h}, the shear profile shows evidence of a second-halo term. This is related to the correlated matter distribution around galaxy clusters and proportional to the so-called halo bias. We present an observational analysis of the halo bias-mass relation based on the AMICO galaxy cluster catalog, comprising around 7000 candidates detected in the third release of the KiDS survey. We split the cluster sample into 14 redshift-richness bins and derive the halo bias and the virial mass in each bin by means of a stacked weak lensing analysis. The observed halo bias-mass relation and the theoretical predictions based on the $Λ$CDM standard cosmological model show an agreement within $2σ$. The mean measurements of bias and mass over the full catalog give $M_{200c} = (4.9 \pm 0.3) \times 10^{13} M_{\odot}/\textit{h}$ and $b_h σ_8^2 = 1.2 \pm 0.1$. With the additional prior of a bias-mass relation from numerical simulations, we constrain the normalization of the power spectrum with a fixed matter density $Ω_m = 0.3$, finding $σ_8 = 0.63 \pm 0.10$.

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arXiv2021

Angular systematics-free cosmological analysis of galaxy clustering in configuration space

Galaxy redshift surveys are subject to incompleteness and inhomogeneous sampling due to the various constraints inherent to spectroscopic observations. This can introduce systematic errors on the summary statistics of interest, which need to be mitigated in cosmological analysis to achieve high accuracy. Standard practices involve applying weighting schemes based on completeness estimates across the survey footprint, possibly supplemented with additional weighting schemes accounting for density-dependent effects. In this work, we concentrate on pure angular systematics and describe an alternative approach consisting in analysing the galaxy two-point correlation function where angular modes are nulled. By construction, this procedure removes all possible known and unknown sources of angular observational systematics, but also part of the cosmological signal.We use a modified Landy-Szalay estimator for the two-point correlation function that relies on an additional random catalogue where angular positions are randomly drawn from the galaxy catalogue, and provide an analytical model to describe this modified statistic. We test the model by performing an analysis of the full anisotropic clustering in mock catalogues of luminous red and emission-line galaxies at 0.43 < z < 1.1. We find that the model fully accounts for the modified correlation function in redshift space, without introducing new nuisance parameters. The derived cosmological parameters from the analysis of baryon acoustic oscillations and redshift-space distortions display slightly larger statistical uncertainties, mostly for the growth rate of structure parameter fs8 that exhibits a 50% statistical error increase, but free from angular systematic error.

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arXiv2021

Halo Mass-Concentration Relation at High-Mass End

The concentration-mass (c-M) relation encodes the key information of the assembly history of the dark matter halos, however its behavior at the high mass end has not been measured precisely in observations yet. In this paper, we report the measurement of halo c-M relation with galaxy-galaxy lensing method, using shear catalog of the Dark Energy Camera Legacy Survey (DECaLS) Data Release 8, which covers a sky area of 9500 deg^2. The foreground lenses are selected from redMaPPer, LOWZ, and CMASS catalogs, with halo mass range from 10^{13} to 10^{15} M_sun and redshift range from z=0.08 to z=0.65. We find that the concentration decreases with the halo mass from 10^{13} to 10^{14} M_sun, but shows a trend of upturn after the pivot point of ~10^{14} M_sun. We fit the measured c-M relation with the concentration model c(M)=C_0 (M/(10^{12} M_sun/h)^{-γ} [1+(M/M_0)^{0.4}], and get the values (C_0, γ, log(M_0) = (5.119_{-0.185}^{0.183}, 0.205_{-0.010}^{0.010}, 14.083_{-0.133}^{0.130}), and (4.875_{-0.208}^{0.209}, 0.221_{-0.010}^{0.010}, 13.750_{-0.141}^{0.142}) for halos with 0.08<=z<0.35 and 0.35<=z<0.65, respectively. We also show that the model including an upturn is favored over a simple power-law model. Our measurement provides important information for the recent argument of massive cluster formation process.

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arXiv2021

The Uchuu Simulations: Data Release 1 and Dark Matter Halo Concentrations

We introduce the Uchuu suite of large high-resolution cosmological $N$-body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion ($12800^3$) dark matter particles in a box of side-length 2.0 Gpc/h, with particle mass $3.27 \times 10^{8}$ Msun/h. The highest resolution simulation, Shin-Uchuu, consists of 262 billion ($6400^3$) particles in a box of side-length 140 Mpc/h, with particle mass $8.97 \times 10^{5}$ Msun/h. Combining these simulations we can follow the evolution of dark matter halos and subhalos spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume. In this first paper, we present basic statistics, dark matter power spectra, and the halo and subhalo mass functions, which demonstrate the wide dynamic range and superb statistics of the Uchuu suite. From an analysis of the evolution of the power spectra we conclude that our simulations remain accurate from the Baryon Acoustic Oscillation scale down to the very small. We also provide parameters of a mass-concentration model, which describes the evolution of halo concentration and reproduces our simulation data to within 5 per cent for halos with masses spanning nearly eight orders of magnitude at redshift 0 0.5, whereas no upturn is detected at z<0.5. We make publicly available various $N$-body products as part of Uchuu Data Release 1 on the Skies & Universes site. Future releases will include gravitational lensing maps and mock galaxy, X-ray cluster, and active galactic nuclei catalogues.

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arXiv2021

Does Concentration Drive the Scatter in the Stellar-to-Halo Mass Relation of Galaxy Clusters?

Concentration is one of the key dark matter halo properties that could drive the scatter in the stellar-to-halo mass relation of massive clusters. We derive robust photometric stellar masses for a sample of brightest central galaxies (BCGs) in SDSS redMaPPer clusters at $0.17<z<0.3$, and split the clusters into two equal-halo mass subsamples by their BCG stellar mass $M_*$. The weak lensing profiles $ΔΣ$ of the two cluster subsamples exhibit different slopes on scales below 1 M$pc/h$. To interpret such discrepancy, we perform a comprehensive Bayesian modelling of the two $ΔΣ$ profiles by including different levels of miscentring effects between the two subsamples as informed by X-ray observations. We find that the two subsamples have the same average halo mass of $1.74 \times 10^{14} M_{\odot}/h$, but the concentration of the low-$M_*$ clusters is $5.87_{-0.60}^{+0.77}$, ${\sim}1.5σ$ smaller than that of their high-$M_*$ counterparts~($6.95_{-0.66}^{+0.78}$). Furthermore, both cluster weak lensing and cluster-galaxy cross-correlations indicate that the large-scale bias of the low-$M_*$, low-concentration clusters are ${\sim}10\%$ higher than that of the high-$M_*$, high-concentration systems, hence possible evidence of the cluster assembly bias effect. Our results reveal a remarkable physical connection between the stellar mass within 20{-}30 k$pc/h$, the dark matter mass within ${\sim}$ 200 k$pc/h$, and the cosmic overdensity on scales above 10 M$pc/h$, enabling a key observational test of theories of co-evolution between massive clusters and their central galaxies.

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arXiv2021

Impact of baryons in cosmic shear analyses with tomographic aperture mass statistics

NonGaussian cosmic shear statistics based on weak-lensing aperture mass ($M_{\rm ap}$) maps can outperform the classical shear two-point correlation function ($γ$-2PCF) in terms of cosmological constraining power. However, reaching the full potential of these new estimators requires accurate modeling of the physics of baryons as the extra nonGaussian information mostly resides at small scales. We present one such modeling based on the Magneticum hydrodynamical simulation for the KiDS-450 and DES-Y1 surveys and a Euclid-like survey. We compute the bias due to baryons on the lensing PDF and the distribution of peaks and voids in $M_{\rm ap}$ maps and propagate it to the cosmological forecasts on the structure growth parameter $S_8$, the matter density parameter $Ω_{\rm m}$, and the dark energy equation of state $w_0$ using the SLICS and cosmo-SLICS sets of dark-matter-only simulations. We report a negative bias of a few percent on $S_8$ and $Ω_{\rm m}$ and also measure a positive bias of the same level on $w_0$ when including a tomographic decomposition. These biases reach $\sim 5$% when combining $M_{\rm ap}$ statistics with the $γ$-2PCF as these estimators show similar dependency on the AGN feedback. We verify that these biases constitute a less than $1σ$ shift on the probed cosmological parameters for current cosmic shear surveys. However, baryons need to be accounted for at the percentage level for future Stage IV surveys and we propose to include the uncertainty on the AGN feedback amplitude by marginalizing over this parameter using multiple simulations such as those presented in this paper. Finally, we explore the possibility of mitigating the impact of baryons by filtering the $M_{\rm ap}$ map but find that this process would require to suppress the small-scale information to a point where the constraints would no longer be competitive.

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arXiv2021

Probing dark energy with tomographic weak-lensing aperture mass statistics

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 $S_8 - Ω_{\rm m} - w_0$ 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 ($γ$-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 $γ$-2PCF compared to the $γ$-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 $γ$-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 $σ_8$ - $Ω_{\rm m}$ tension, but also constitutes an avenue to understand the accelerated expansion of our Universe.

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arXiv2020

Unveiling the Intrinsic Alignment of Galaxies with Self-Calibration and DECaLS DR3 data

Galaxy intrinsic alignment (IA) is both a source of systematic contamination to cosmic shear measurement and its cosmological applications, and a source of valuable information on the large scale structure of the universe and galaxy formation. The self-calibration (SC) method \citep{SC2008} was designed to separate IA from cosmic shear, free of IA modeling. It was first successfully applied to the KiDS450 and KV450 data \citep{Yao2019}. We apply the SC method to the DECaLS DR3 shear + photo-z catalog and significantly improve the IA detection to $\sim 14σ$. We find a strong dependence of IA on galaxy color, with strong IA signal ($\sim17.6σ$) for red galaxies, while the IA signal for blue galaxies is consistent with zero. The detected IA for red galaxies are in reasonable agreement with the non-linear tidal alignment model and the inferred IA amplitude increases with redshift. We address the systematics in the SC method carefully and performed several sanity checks. We discuss various caveats and possible improvements in the measurement, theory and parameter fitting that will be addressed in future works.

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arXiv2020

The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Large-scale Structure Catalogs for Cosmological Analysis

We present large-scale structure catalogs from the completed extended Baryon Oscillation Spectroscopic Survey (eBOSS). Derived from Sloan Digital Sky Survey (SDSS) -IV Data Release 16 (DR16), these catalogs provide the data samples, corrected for observational systematics, and random positions sampling the survey selection function. Combined, they allow large-scale clustering measurements suitable for testing cosmological models. We describe the methods used to create these catalogs for the eBOSS DR16 Luminous Red Galaxy (LRG) and Quasar samples. The quasar catalog contains 343,708 redshifts with $0.8 < z < 2.2$ over 4,808\,deg$^2$. We combine 174,816 eBOSS LRG redshifts over 4,242\,deg$^2$ in the redshift interval $0.6 < z < 1.0$ with SDSS-III BOSS LRGs in the same redshift range to produce a combined sample of 377,458 galaxy redshifts distributed over 9,493\,deg$^2$. Improved algorithms for estimating redshifts allow that 98 per cent of LRG observations result in a successful redshift, with less than one per cent catastrophic failures ($Δz > 1000$ ${\rm km~s}^{-1}$). For quasars, these rates are 95 and 2 per cent (with $Δz > 3000$ ${\rm km~s}^{-1}$). We apply corrections for trends between the number densities of our samples and the properties of the imaging and spectroscopic data. For example, the quasar catalog obtains a $χ^2$/DoF$= 776/10$ for a null test against imaging depth before corrections and a $χ^2$/DoF$=6/8$ after. The catalogs, combined with careful consideration of the details of their construction found here-in, allow companion papers to present cosmological results with negligible impact from observational systematic uncertainties.

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arXiv2020

The BUFFALO HST Survey

The Beyond Ultra-deep Frontier Fields and Legacy Observations (BUFFALO) is a 101 orbit + 101 parallel Cycle 25 Hubble Space Telescope Treasury program taking data from 2018-2020. BUFFALO will expand existing coverage of the Hubble Frontier Fields (HFF) in WFC3/IR F105W, F125W, and F160W and ACS/WFC F606W and F814W around each of the six HFF clusters and flanking fields. This additional area has not been observed by HST but is already covered by deep multi-wavelength datasets, including Spitzer and Chandra. As with the original HFF program, BUFFALO is designed to take advantage of gravitational lensing from massive clusters to simultaneously find high-redshift galaxies which would otherwise lie below HST detection limits and model foreground clusters to study properties of dark matter and galaxy assembly. The expanded area will provide a first opportunity to study both cosmic variance at high redshift and galaxy assembly in the outskirts of the large HFF clusters. Five additional orbits are reserved for transient followup. BUFFALO data including mosaics, value-added catalogs and cluster mass distribution models will be released via MAST on a regular basis, as the observations and analysis are completed for the six individual clusters.

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arXiv2020

hybrid-Lenstool: A self-consistent algorithm to model galaxy clusters with strong- and weak-lensing simultaneously

We present a new galaxy cluster lens modeling approach, hybrid-Lenstool, that is implemented in the publicly available modeling software Lenstool. hybrid-Lenstool combines a parametric approach to model the core of the cluster, and a non-parametric (free-form) approach to model the outskirts. hybrid-Lenstool optimizes both strong- and weak-lensing constraints simultaneously (Joint-Fit), providing a self-consistent reconstruction of the cluster mass distribution on all scales. In order to demonstrate the capabilities of the new algorithm, we tested it on a simulated cluster. hybrid-Lenstool yields more accurate reconstructed mass distributions than the former Sequential-Fit approach where the parametric and the non-parametric models are optimized successively. Indeed, we show with the simulated cluster that the mass density profile reconstructed with a Sequential-Fit deviates form the input by $2-3σ$ at all scales while the Joint-Fit gives a profile that is within $1-1.5σ$ of the true value. This gain in accuracy is consequential for recovering mass distributions exploiting cluster lensing and therefore for all applications of clusters as cosmological probes. Finally we found that the Joint-Fit approach yields shallower slope of the inner density profile than the Sequential-Fit approach, thus revealing possible biases in previous lensing studies.

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arXiv2019

Weak Lensing Analysis of CODEX Clusters using Dark Energy Camera Legacy Survey : Mass-Richness Relation

We present the weak lensing analysis of 279 CODEX clusters using imaging data from 4200 $\text{deg}^{2}$ of the DECam Legacy Survey (DECaLS) Data Release 3. The cluster sample results from a joint selection in X-ray, optical richness in the range $20 \leq λ< 110$, and redshift in the range $0.1 \leq z \leq 0.2$. We model the cluster mass ($M_{\rm 200c}$) and the richness relation with the expression $\left\langle M_{\rm 200c} | λ\right\rangle \propto M_{0} \, (λ/ 40)^{F_λ}$. By measuring the CODEX cluster sample as an individual cluster, we obtain the best-fit values, $M_{0} = 3.24^{+0.29}_{-0.27} \times 10^{14} \text{M}_{\odot}$, and $F_λ = 1.00 ^{+0.22}_{-0.22}$ for the richness scaling index, consistent with a power law relation. Moreover, we separate the cluster sample into three richness groups; $λ= 20 - 30, 30 - 50$ and $50 - 110$, and measure the stacked excess surface mass density profile in each group. The results show that both methods are consistent. In addition, we find an excellent agreement between our weak lensing based scaling relation and the relation obtained with dynamical masses estimated from cluster member velocity dispersions measured by the SDSS-IV/SPIDERS team. This suggests that the cluster dynamical equilibrium assumption involved in the dynamical mass estimates is statistically robust for a large sample of clusters.

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arXiv2019

Dark matter stripping in galaxy clusters: a look at the Stellar to Halo Mass relation in the Illustris simulation

Satellite galaxies in galaxy clusters represent a significant fraction of the global galaxy population. Because of the unusual dense environment of clusters, their evolution is driven by different mechanisms than the ones affecting field or central galaxies. Understanding the different interactions they are subject to, and how they are influenced by them, is therefore an important step towards explaining the global picture of galaxy evolution. In this paper, we use the publicly-available high resolution hydrodynamical simulation Illustris-1 to study satellite galaxies in the three most massive host haloes (with masses $M_{200} > 10^{14}\,h^{-1}\rm{M}_{\odot}$) at $z=0$. We measure the Stellar-to-Halo Mass Relation (hereafter SHMR) of the galaxies, and find that for satellites it is shifted towards lower halo masses compared to the SHMR of central galaxies. We provide simple fitting functions for both the central and satellite SHMR. To explain the shift between the two, we follow the satellite galaxies since their time of accretion into the clusters, and quantify the impact of dark matter stripping and star formation. We find that subhaloes start losing their dark matter as soon as they get closer than $\sim 1.5\times R_{\rm{vir}}$ to the centre of their host, and that up to 80\% of their dark matter content gets stripped during infall. On the other hand, star formation quenching appears to be delayed, and galaxies continue to form stars for a few Gyr after accretion. The combination of these two effects impacts the ratio of stellar to dark matter mass which varies drastically during infall, from 0.03 to 0.3.

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arXiv2019

The Strong Gravitational Lens Finding Challenge

Large scale imaging surveys will increase the number of galaxy-scale strong lensing candidates by maybe three orders of magnitudes beyond the number known today. Finding these rare objects will require picking them out of at least tens of millions of images and deriving scientific results from them will require quantifying the efficiency and bias of any search method. To achieve these objectives automated methods must be developed. Because gravitational lenses are rare objects reducing false positives will be particularly important. We present a description and results of an open gravitational lens finding challenge. Participants were asked to classify 100,000 candidate objects as to whether they were gravitational lenses or not with the goal of developing better automated methods for finding lenses in large data sets. A variety of methods were used including visual inspection, arc and ring finders, support vector machines (SVM) and convolutional neural networks (CNN). We find that many of the methods will be easily fast enough to analyse the anticipated data flow. In test data, several methods are able to identify upwards of half the lenses after applying some thresholds on the lens characteristics such as lensed image brightness, size or contrast with the lens galaxy without making a single false-positive identification. This is significantly better than direct inspection by humans was able to do. (abridged)

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arXiv2018

Strong lensing modeling in galaxy clusters as a promising method to test cosmography I. Parametric dark energy models

In this paper we probe five cosmological models for which the dark energy equation of state parameter, $w(z)$, is parameterized as a function of redshift using strong lensing data in the galaxy cluster Abell 1689. We constrain the parameters of the $w(z)$ functions by reconstructing the lens model under each one of these cosmologies with strong lensing measurements from two galaxy clusters: Abell 1689 and a mock cluster, Ares, from the Hubble Frontier Fields Comparison Challenge, to validate our methodology. To quantify how the cosmological constraints are biased due to systematic effects in the strong lensing modeling, we carry out three runs considering the following uncertainties for the multiple images positions: 0.25", 0.5", and 1.0". With Ares, we find that larger errors decrease the systematic bias on the estimated cosmological parameters. With real data, our strong-lensing constraints on $w(z)$ are consistent those derived from other cosmological probes. We confirm that strong lensing cosmography with galaxy clusters is a promising method to constrain $w(z)$ parameterizations. A better understanding of galaxy clusters and their environment is however needed to improve the SL modeling and hence to estimate stringent cosmological parameters in alternatives cosmologies.

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