The Halo Boundary of Galaxy Clusters in the SDSS

Mass around dark matter halos can be divided into "infalling" material and "collapsed" material that has passed through at least one pericenter. Analytical models and simulations predict a rapid drop in the halo density profile associated with the transition between these two regimes. Using data from SDSS, we explore the evidence for such a feature in the density profiles of galaxy clusters and investigate the connection between this feature and a possible phase space boundary. We first estimate the steepening of the outer galaxy density profile around clusters: the profiles show an abrupt steepening, providing evidence for truncation of the halo profile. Next, we measure the galaxy density profile around clusters using two sets of galaxies selected based on color. We find evidence of an abrupt change in the galaxy colors that coincides with the location of the steepening of the density profile. Since galaxies are likely to be quenched of star formation and turn red inside of clusters, this change in the galaxy color distribution can be interpreted as the transition from an infalling regime to a collapsed regime. We also measure this transition using a model comparison approach which has been used recently in studies of the "splashback" phenomenon, but find that this approach is not a robust way to quantify the significance of detecting a splashback-like feature. Finally, we perform measurements using an independent cluster catalog to test for potential systematic errors associated with cluster selection. We identify several avenues for future work: improved understanding of the small-scale galaxy profile, lensing measurements, identification of proxies for the halo accretion rate, and other tests. With upcoming data from the DES, KiDS and HSC surveys, we can expect significant improvements in the study of halo boundaries.Comment: 17 pages, 8 figure

Constraints on Dark Matter Self-Interactions from weak lensing of galaxies from the Dark Energy Survey around clusters from the Atacama Cosmology Telescope Survey

Self--interactions of dark matter particles impact the distribution of dark matter in halos. The exact nature of the self--interactions can lead to either expansion or collapse of the core within the halo lifetime, leaving distinctive signatures in the dark matter distributions not only at the halo center but throughout the virial region. Optical galaxy surveys, which precisely measure the weak lensing of background galaxies by massive foreground clusters, allow us to directly measure the matter distribution within clusters and probe subtle effects of self--interacting dark matter (SIDM) throughout the halo's full radial range. We compare the weak--lensing measurements reported by Shin et al. 2021, which use lens clusters identified by the Atacama Cosmology Telescope Survey and source galaxies from the Dark Energy Survey, with predictions from SIDM models having either elastic or dissipative self--interactions. To model the weak--lensing observables, we use cosmological N-body simulations for elastic self--interactions and semi-analytical fluid simulations for dissipative self--interactions. We find that current weak--lensing measurements already constrain the isotropic and elastic SIDM to a cross-section per mass of $\sigma/m<1~{\rm cm^2/g}$ at a $95\%$ confidence level. The same measurements also impose novel constraints on the energy loss per unit mass for dissipative SIDM. Upcoming surveys are anticipated to enhance the signal-to-noise of weak--lensing observables significantly making them effective tools for investigating the nature of dark matter, including self--interactions, through weak lensing

Shocks in the Stacked Sunyaev-Zel'dovich Profiles of Clusters I: Analysis with the Three Hundred Simulations

Gas infalling into the gravitational potential wells of massive galaxy clusters is expected to experience one or more shocks on its journey to becoming part of the intracluster medium (ICM). These shocks are important for setting the thermodynamic properties of the ICM and can therefore impact cluster observables such as X-ray emission and the Sunyaev-Zel'dovich (SZ) effect. We investigate the possibility of detecting signals from cluster shocks in the averaged thermal SZ profiles of galaxy clusters. Using zoom-in hydrodynamic simulations of massive clusters from the Three Hundred Project, we show that if cluster SZ profiles are stacked as a function of $R/R_{200m}$, shock-induced features appear in the averaged SZ profile. These features are not accounted for in standard fitting formulae for the SZ profiles of galaxy clusters. We show that the shock features should be detectable with samples of clusters from ongoing and future SZ surveys. We also demonstrate that the location of these features is correlated with the cluster accretion rate, as well as the location of the cluster splashback radius. Analyses of ongoing and future surveys, such as SPT-3G, AdvACT, Simons Observatory and CMB-S4, that include gas shocks will gain a new handle on the properties and dynamics of the outskirts of massive halos, both in gas and in mass.Comment: 13 pages, 8 figures; matches version accepted by MNRA

Physico-Chemical &amp;Microbial Assessment of Ground Water of DCM Industrial Area and Its Adjoining Areas, Kota [India].Part I

, As, Cu, Zn along with EC and Coli form Organism indicate towards major health concerns of living beings. On comparing results with drinking water quality standards laid down by WHO, it is found that most of the water samples are non potable for human beings due high concentration of one parameters or the other. Most of the samples have EC, free NH 4 , Coli form Organism much higher than the maximum permissible levels set up by WHO which are 300 μmhos/cm, 1.2 mg/L,&lt;500 mg/L respectively. The high values of these parameters have health implications require adequate time bound remedial measures. KEY WORDS: Ground water, physicochemical analysis, drinking water quality, health implications

Splashback in galaxy clusters as a probe of cosmic expansion and gravity

The splashback radius is a physical scale in dark matter halos that is set by the gravitational dynamics of recently accreted shells. We use analytical models and N-body simulations to study the dependence of splashback on dark energy and screened modified gravity theories. In modified gravity models, the transition from screened to unscreened regions typically occurs in the cluster outskirts, suggesting potentially observable signatures in the splashback feature. We investigate the location of splashback in both chameleon and Vainshtein screened models and find significant differences compared with ΛCDM predictions. We also find an interesting interplay between dynamical friction and modified gravity, providing a distinctive signature for modified gravity models in the behavior of the splashback feature as a function of galaxy luminosity

Adsorption of Cadmium from aqueous solution onto coffee grounds and wheat straw: Equilibrium and Kinetics Study

The adsorption kinetics of cadmium (Cd) from wastewater onto coffee grounds and wheat straw was ascertained under different process conditions. Batch tests were performed to study the effect of pH, adsorbent concentration, contact time and initial metal concentration on the removal of cadmium. The adsorption kinetics was envisaged by fitting the experimental data to the pseudo-first order and pseudo-second order kinetic models; and based on linear regression analysis, the best fit was found to be for the pseudo-second order kinetic model for both the adsorbents. Equilibrium conditions were achieved in less than 30 min. Two isotherm equations, namely Langmuir and Freundlich models were also used to fit the experimental adsorption equilibrium data. The results showed that both physisorption and chemisorption mechanisms controlled the adsorption rate and capacity. The maximum adsorption capacity of coffee grounds and wheat straw was calculated to be 16.2 mg/g and 31.6 mg/g, respectively.status: publishe

Three dimensional evaluation of accuracy of bracket positioning

Introduction: The success of orthodontic treatment depends on accurate bracket placement, so researchers are constantly exploring new direct and indirect bonding methods with the help of cutting-edge imaging technologies like cone beam computed tomography (CBCT), which provides full three-dimensional visualization of tissues down to the root of the tooth. Aim: The primary goals of this analysis are to determine the degree of section angulation and adhesive thickness, as well as the accuracy of the vertical and flat section positions. The correlation between total clinical crown height, minor edge to focus of section, and minimum edge to complete curve crown length is one of several possible goals of this investigation (FACC). Materials and Methods: Currently, 10 patients aged 15-30 who needed fixed appliance treatment were enrolled in an in vivo research conducted by the orthodontics department. Cases with and without extractions of the crooked teeth were counted. Full mouth analysis is being used in this investigation. Ten patients were selected at random and placed in either Group A (the study group) or Group B (the control group) (control group). Group A bonds are more indirect, whereas group B bonds are more like “normal” direct bonds. We used a Canon 700D camera, a biocompatible transparent 3D printing resin, and a 3M Gemini MBT.022 in bracket kit for CT scanning and imaging. Brackets are placed by experienced orthodontists in both treatment groups. Result: There is a statistically significant (P 0.05) difference between the indirect and direct bonding group when all five factors are taken into account, with the indirect bonding group demonstrating superiority in terms of accuracy. Conclusion: The results of the current investigation support the premise that there is a clinically significant difference between direct bonding and 3D indirect bonding in terms of bracket placement accuracy