Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCore Mass Estimates in Strong Lensing Galaxy Clusters Using a Single-Halo Lens Model
107
0
0.0
(
0
)
Added by
Juan Remolina Gonz\\'alez
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
The core mass of galaxy clusters is an important probe of structure formation. Here, we evaluate the use of a Single-Halo model (SHM) as an efficient method to estimate the strong lensing cluster core mass, testing it with ray-traced images from the `Outer Rim simulation. Unlike detailed lens models, the SHM represents the cluster mass distribution with a single halo and can be automatically generated from the measured lensing constraints. We find that the projected core mass estimated with this method, M$_{rm SHM}$, has a scatter of $8.52%$ and a bias of $0.90%$ compared to the true mass within the same aperture. Our analysis shows no systematic correlation between the scatter or bias and the lens-source system properties. The bias and scatter can be reduced to $3.26%$ and $0.34%$, respectively, by excluding models that fail a visual inspection test. We find that the SHM success depends on the lensing geometry, with single giant arc configurations accounting for most of the failed cases due to their limiting constraining power. When excluding such cases, we measure a scatter and bias of $3.88%$ and $0.84%$, respectively. Finally, we find that when the source redshift is unknown, the model-predicted redshifts are overestimated, and the M$_{rm SHM}$ is underestimated by a few percent, highlighting the importance of securing spectroscopic redshifts of background sources. Our analysis provides a quantitative characterization of M$_{rm SHM}$, enabling its efficient use as a tool to estimate the strong lensing cluster core masses in the large samples, expected from current and future surveys.
rate research
Read More
The core mass of galaxy clusters is both an important anchor of the radial mass distribution profile and probe of structure formation. With thousands of strong lensing galaxy clusters being discovered by current and upcoming surveys, timely, efficient, and accurate core mass estimates are needed. We assess the results of two efficient methods to estimate the core mass of strong lensing clusters: the mass enclosed by the Einstein radius ($M_{corr}(<theta_E)$ where $theta_{rm E}$ is approximated from arc positions; Remolina Gonz{a}lez et al. 2020), and single-halo lens model ($M_{rm{SHM}}(<rm{e}theta_{rm{E}})$; Remolina Gonz{a}lez et al. 2021), against measurements from publicly available detailed lens models ($M_{rm{DLM}}$) of the same clusters. We use data from the Sloan Giant Arc Survey, the Reionization Lensing Cluster Survey, the Hubble Frontier Fields, and the Cluster Lensing and Supernova Survey with Hubble. We find a scatter of $18.3%$ ($8.4%$) with a bias of $-7.5%$ ($0.4%$) between $M_{corr}(<theta_E)$ ($M_{rm{SHM}}(<rm{e}theta_{rm{E}})$) and $M_{rm{DLM}}$. Last, we compare the statistical uncertainties measured in this work to those from simulations. This work demonstrates the successful application of these methods to observational data. As the effort to efficiently model the mass distribution of strong lensing galaxy clusters continues, we need fast, reliable methods to advance the field.
We present an axially symmetric formula to calculate the probability of finding gravitational arcs in galaxy clusters, being induced by their massive dark matter haloes, as a function of clusters redshifts and virial masses. The formula includes the ellipticity of the clusters dark matter potential by using a pseudo-elliptical approximation. The probabilities are calculated and compared for two dark-matter halo profiles, the Navarro, Frenk and White (NFW) and the Non-Singular-Isothermal-Sphere (NSIS). We demonstrate the power of our formulation through a Kolmogorov-Smirnov (KS) test on the strong lensing statistics of an X-ray bright sample of low redshift Abell clusters. This KS test allows to establish limits on the values of the concentration parameter for the NFW profile ($c_Delta$) and the core radius for the NSIS profile (rc), which are related to the lowest cluster redshift ($z_{rm cut}$) where strong arcs can be observed. For NFW dark matter profiles, we infer cluster haloes with concentrations that are consistent to those predicted by $Lambda$CDM simulations. As for NSIS dark matter profiles, we find only upper limits for the clusters core radii and thus do not rule out a purely SIS model. For alternative mass profiles, our formulation provides constraints through $z_{rm cut}$ on the parameters that control the concentration of mass in the inner region of the clusters haloes. We find that $z_{rm cut}$ is expected to lie in the 0.0--0.2 redshift, highlighting the need to include very low-$z$ clusters in samples to study the clusters mass profiles.
In the era of large surveys, yielding thousands of galaxy clusters, efficient mass proxies at all scales are necessary in order to fully utilize clusters as cosmological probes. At the cores of strong lensing clusters, the Einstein radius can be turned into a mass estimate. This efficient method has been routinely used in literature, in lieu of detailed mass models; however, its scatter, assumed to be $sim30%$, has not yet been quantified. Here, we assess this method by testing it against ray-traced images of cluster-scale halos from the Outer Rim N-body cosmological simulation. We measure a scatter of $13.9%$ and a positive bias of $8.8%$ in $M(<theta_E)$, with no systematic correlation with total cluster mass, concentration, or lens or source redshifts. We find that increased deviation from spherical symmetry increases the scatter; conversely, where the lens produces arcs that cover a large fraction of its Einstein circle, both the scatter and the bias decrease. While spectroscopic redshifts of the lensed sources are critical for accurate magnifications and time delays, we show that for the purpose of estimating the total enclosed mass, the scatter introduced by source redshift uncertainty is negligible compared to other sources of error. Finally, we derive and apply an empirical correction that eliminates the bias, and reduces the scatter to $10.1%$ without introducing new correlations with mass, redshifts, or concentration. Our analysis provides the first quantitative assessment of the uncertainties in $M(<theta_E)$, and enables its effective use as a core mass estimator of strong lensing galaxy clusters.
[Abridged] We present a comparison between weak-lensing (WL) and X-ray mass estimates of a sample of numerically simulated clusters. The sample consists on the 20 most massive objects at redshift z=0.25 and Mvir > 5 x 10^{14} Msun h^{-1}. They were found in a cosmological simulation of volume 1 h^{-3} Gpc^3, evolved in the framework of a WMAP-7 normalized cosmology. Each cluster has been resimulated at higher resolution and with more complex gas physics. We processed it thought Skylens and X-MAS to generate optical and X-ray mock observations along three orthogonal projections. The optical simulations include lensing effects on background sources. Standard observational tools and methods of analysis are used to recover the mass profiles of each cluster projection from the mock catalogues. Given the size of our sample, we could also investigate the dependence of the results on cluster morphology, environment, temperature inhomogeneity, and mass. We confirm previous results showing that WL masses obtained from the fit of the cluster tangential shear profiles with NFW functionals are biased low by ~ 5-10% with a large scatter (~10-25%). We show that scatter could be reduced by optimally selecting clusters either having regular morphology or living in substructure-poor environment. The X-ray masses are biased low by a large amount (~25-35%), evidencing the presence of both non-thermal sources of pressure in the ICM and temperature inhomogeneity, but they show a significantly lower scatter than weak-lensing-derived masses. The X-ray mass bias grows from the inner to the outer regions of the clusters. We find that both biases are weakly correlated with the third-order power ratio, while a stronger correlation exists with the centroid shift. Finally, the X-ray bias is strongly connected with temperature inhomogeneities.
A defining prediction of the cold dark matter (CDM) cosmological model is the existence of a very large population of low-mass haloes. This population is absent in models in which the dark matter particle is warm (WDM). These alternatives can, in principle, be distinguished observationally because halos along the line-of-sight can perturb galaxy-galaxy strong gravitational lenses. Furthermore, the WDM particle mass could be deduced because the cut-off in their halo mass function depends on the mass of the particle. We systematically explore the detectability of low-mass haloes in WDM models by simulating and fitting mock lensed images. Contrary to previous studies, we find that halos are harder to detect when they are either behind or in front of the lens. Furthermore, we find that the perturbing effect of haloes increases with their concentration: detectable haloes are systematically high-concentration haloes, and accounting for the scatter in the mass-concentration relation boosts the expected number of detections by as much as an order of magnitude. Haloes have lower concentration for lower particle masses and this further suppresses the number of detectable haloes beyond the reduction arising from the lower halo abundances alone. Taking these effects into account can make lensing constraints on the value of the mass function cut-off at least an order of magnitude more stringent than previously appreciated.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
