Proxy For Mass Research Articles

Effect of blade inclination angle for straight-bladed vertical-axis wind turbines

Abstract. Vertical-axis wind turbines (VAWTs) have received renewed research interest in the offshore environment due to a number of design synergies that have the potential to decrease the cost of energy for offshore wind. Many studies have been completed on the rotor design for straight-bladed rotors (H-rotors); however, there is sparse information on the effect of blade inclination angle on VAWT aerodynamic performance and the optimal blade design of VAWTs with inclined blades (V-rotors) for maximum power capture. This paper presents a systematic study into the effect of blade inclination angle and chord distribution on VAWT performance for different aspect ratios using a 3D implementation of the 2D actuator cylinder model which has been previously validated against higher-fidelity methods. A systematic approach based on a grid search is used to allow the wider design space to be studied and trends identified. In the case of fixed-chord-length blades, it is found that significant power gains are available through blade inclination, between 12 % and 71 % depending on blade length. This is driven by the increase in rotor swept area. Further investigation indicates that despite this, under maximum blade stress limitations the most economical solution for fixed-chord-length blades is H-rotors. Optimal chord distributions, which maximise the rotor power coefficient, are then obtained, and a natural blade taper is observed. For rotors with optimal chord distributions, similar power gains are observed through blade inclination, again between 12 % and 71 % depending on blade length. However, rotor configurations with the largest power gains are found to have significantly increased blade mass. For a given power rating, whilst satisfying limitations on maximum blade root bending stress, it is found that blade volume, a proxy for the blade mass, can be reduced between 16 % and 42 % dependent on blade length, and rotor torque can be reduced between 4 % and 9 %. This indicates the potential of V-rotors to reduce the cost of energy compared to H-rotors in traditional VAWT designs. Additionally, inclined blades are shown to increase the operational tip-speed ratio, demonstrating their applicability to turbines using secondary rotors, such as the X-rotor, where high tip-speed ratios are required for efficient power conversion between primary and secondary rotors.

Letter to Editor - The Potential of Body Mass Index-Adjusted Calf Circumference as a Proxy for Low Muscle Mass in the Global Leadership Initiative on Malnutrition Criteria

Letter to Editor - The Potential of Body Mass Index-Adjusted Calf Circumference as a Proxy for Low Muscle Mass in the Global Leadership Initiative on Malnutrition Criteria

The relationship between primate distal fibula trabecular architecture and arboreality, phylogeny and size.

The fibula, despite being traditionally overlooked compared to the femur and the tibia, has recently received attention in primate functional morphology due to its correlation with the degree of arboreality (DOA). Highlighting further fibular features that are associated with arboreal habits would be key to improving palaeobiological inferences in fossil specimens. Here we present the first investigation on the trabecular bone structure of the primate fibula, focusing on the distal epiphysis, across a vast array of species. We collected μCT data on the distal fibula for 21 species of primates, with representatives from most of the orders, and we employed a recently developed approach implemented in the R package 'indianaBones' to isolate the entire trabecular bone underlying an epiphysis or articular facet. After extracting both traditional trabecular parameters and novel topological indices, we tested for the posited relationship between trabecular bone and DOA. To disentangle this effect from others related to body size and phylogenetic relationship, we included a body mass proxy as covariate and employed phylogenetic comparative methods. We ran univariate/multivariate and exploratory/inferential statistical analyses. The trabecular structure of the fibular distal epiphysis in primates does not appear to be associated with the DOA. Instead, it is strongly affected by body mass and phylogenetic relationships. Although we identified some minor trends related to human bipedalism, our findings overall discourage, at this stage, the study of distal fibula trabecular bone to infer arboreal behaviors in extinct primates. We further found that body size distribution is strongly related to phylogeny, an issue preventing us from unravelling the influence of the two factors and that we believe can potentially affect future comparative analyses of primates. Overall, our results add to previous evidence of how trabecular traits show variable correlation with locomotor aspects, size and phylogenetic history across the primate skeleton, thus outlining a complex scenario in which a network of interconnected factors affects the morphological evolution of primates. This work may represent a starting point for future studies, for example, focusing on the effect of human bipedalism on distal fibula trabecular bone, or aiming to better understand the effects of body size and phylogenetic history on primate morphological evolution.

X-ray and optical analysis of the distant merging double cluster SPT-CLJ2228-5828, its gas bridge, and its shock front

Galaxy cluster mergers are excellent laboratories for studying a wide variety of different physical phenomena. An example of such a cluster system is the distant SPT-CLJ2228-5828 merger located at z≈ 0.77. Previous analyses via the thermal Sunyaev-Zeldovich effect and weak lensing (WL) data suggested that the system was potentially a dissociative cluster post-merger, similar to the Bullet cluster. In this work, we perform an X-ray and optical follow-up analysis of this rare system. We used new deep XMM-Newton data to study the hot gas in X-rays in great detail, spectroscopic Gemini data to precisely determine the redshift of the two mass concentrations, and new Hubble Space Telescope data to improve the total mass estimates of the two components. We find that SPT-CLJ2228-5828 constitutes a pre-merging double cluster system instead of a post-merger as previously thought. The merging process of the two clusters has started, with their gas on the outskirts colliding with a ∼ 22^ ∘ ∘ on the plane of the sky. Both clusters have a similar radius of R_ ∼ 700 kpc, with the two X-ray emission peaks separated by ≈ 1 Mpc (2.1^ We fully characterized the surface brightness, gas density, temperature, pressure, and entropy profiles of the two merging clusters for their undisturbed non-interacting side. The two systems have very similar X-ray properties, with a moderate cluster mass of tot ∼ (2.1-2.4) ⊙ according to X-ray mass proxies. Both clusters show good agreement with known X-ray scaling relations when their merging side is ignored. The WL mass estimate of the western cluster agrees well with the X-ray-based mass, whereas the eastern cluster is surprisingly only marginally detected from its WL signal. A gas bridge with ≈ 333 kpc length connecting the two merging halos is detected at a $5.8σ$ level. The baryon overdensity of the excess gas (not associated with the cluster gas) is δ_ b ∼ (75-320) across the length of the bridge, and its gas mass is M_ gas ∼ 1.4 ⊙ . The gas density and temperature jumps at ∼ 10^ cm^-3 and ∼ 5.5 keV, respectively, are also found across the gas bridge, revealing the existence of a weak shock front with a Mach number mathcal M ∼ 1.1. The gas pressure and entropy also increase at the position of the shock front. We estimate the age of the shock front to be lesssim 100 Myr and its kinetic energy ∼ 2.4 erg s^-1. SPT-CLJ2228-5828 is the first such high-z pre-merger with a gas bridge and a shock front, consisting of similarly sized clusters, to be studied in X-rays.

Gas thermodynamics meets galaxy kinematics: Joint mass measurements for eROSITA galaxy clusters

The mass of galaxy clusters is a critical quantity for probing cluster cosmology and testing theories of gravity, but its measurement could be biased, given that assumptions are inevitable in order to make use of any approach. In this paper, we employ and compare two mass proxies for galaxy clusters: thermodynamics of the intracluster medium and kinematics of member galaxies. We selected 22 galaxy clusters from the cluster catalog in the first SRG/eROSITA All-Sky Survey (eRASS1) that have sufficient optical and near-infrared observations. We generated multiband images in the energy range of (0.3, 7) keV for each cluster, and derived their temperature profiles, gas mass profiles, and hydrostatic mass profiles using a parametric approach that does not assume dark matter halo models. With spectroscopically confirmed member galaxies collected from multiple surveys, we numerically solved the spherical Jeans equation for their dynamical mass profiles. Our results quantify the correlation between dynamical mass and the line-of-sight velocity dispersion, $ dyn los ^2r_ proj /G) - (3.87 with a root mean square (rms) scatter of 0.14 dex. We find that the two mass proxies lead to roughly the same total mass, with no observed systematic bias. As such, the $ tension is not specific to hydrostatic mass or weak lensing shears, but also appears with galaxy kinematics. Interestingly, the hydrostatic-to-dynamical mass ratios decrease slightly toward large radii, which could possibly be evidence for accreting galaxies in the outskirts. We also compared our hydrostatic masses with the latest weak lensing masses inferred with scaling relations. The comparison shows that the weak lensing mass is significantly higher than our hydrostatic mass by sim 110<!PCT!>. This might explain the significantly larger value of $ from the latest measurement using eRASS1 clusters than almost all previous estimates in the literature. Finally, we tested the radial acceleration relation established in disk galaxies. We confirm the missing baryon problem in the inner region of galaxy clusters using three independent mass proxies for the first time. As ongoing and planned surveys are providing deeper X-ray observations and more galaxy spectra for cluster members, we expect to extend the study to cluster outskirts in the near future.

The potential of body mass index-adjusted calf circumference as a proxy for low muscle mass in the global leadership initiative on malnutrition criteria

Background & AimsReduced muscle mass is one of the diagnostic components for Global Leadership Initiative on Malnutrition (GLIM), with various assessment methods proposed. Calf circumference (CC), a representative anthropometric marker of skeletal muscle mass, is now recommended to adjustment based on body mass index (BMI). This study aimed to evaluate the validity and efficacy of BMI-adjusted CC in very older adults, compared with other methods of assessing muscle mass. MethodsThis prospective cohort study included 284 patients aged 65 years and older who were admitted to the Department of Geriatric Medicine at the National Center for Geriatrics and Gerontology Hospital. Health indicators, including nutritional status, were assessed upon admission. Three months after discharge, a telephone survey was conducted to assess patients’ living conditions and survival status. Skeletal muscle mass was estimated using a dual-energy X-ray absorptiometry (DXA); moreover, anthropometric measurements (unadjusted and BMI-adjusted CC) were used as markers of muscle mass. Logistic regression analysis was performed to examine the association between mortality and GLIM-based malnutrition, using each muscle mass assessment method. ResultsThe mean age of the patients was 86.2 ± 6.2 years, and 60.9% were women. The prevalence of GLIM-based malnutrition ranged from 55.3% to 58.8% across the three methods used to assess reduced muscle mass. Three months after discharge, 244 patients were followed up, of whom 29 (11.9%) died. Multivariate logistic regression analysis, adjusted for age, sex, and comorbidities, showed that all methods significantly predicted 3-month mortality, with odds ratios of 5.67, 5.44, and 4.90 for unadjusted CC, BMI-adjusted CC, and appendicular skeletal muscle mass index using DXA, respectively. The prevalence and survival-predictive ability were similar across all methods. ConclusionGLIM-based malnutrition, diagnosed using different methods for assessing muscle mass, similarly predicted 3-month mortality in patients admitted to an acute geriatric ward. These results suggest that BMI-adjusted CC are sufficient alternatives when technical measurements such as DXA are not feasible.

The FLAMINGO project: a comparison of galaxy cluster samples selected on mass, X-ray luminosity, Compton-Y parameter, or galaxy richness

ABSTRACT Galaxy clusters provide an avenue to expand our knowledge of cosmology and galaxy evolution. Because it is difficult to accurately measure the total mass of a large number of individual clusters, cluster samples are typically selected using an observable proxy for mass. Selection effects are therefore a key problem in understanding galaxy cluster statistics. We make use of the $(2.8~\rm {Gpc})^3$ FLAMINGO hydrodynamical simulation to investigate how selection based on X-ray luminosity, thermal Sunyaev–Zeldovich effect or galaxy richness influences the halo mass distribution. We define our selection cuts based on the median value of the observable at a fixed mass and compare the resulting samples to a mass-selected sample. We find that all samples are skewed towards lower mass haloes. For X-ray luminosity and richness cuts below a critical value, scatter dominates over the trend with mass and the median mass becomes biased increasingly low with respect to a mass-selected sample. At $z\le 0.5$, observable cuts corresponding to median halo masses between $M_\text{500c}=10^{14}$ and $10^{15}~\rm {{\rm M}_{\odot }}$ give nearly unbiased median masses for all selection methods, but X-ray selection results in biased medians for higher masses. For cuts corresponding to median masses $\lt 10^{14}$ at $z\le 0.5$ and for all masses at $z\ge 1$, only Compton-Y selection yields nearly unbiased median masses. Importantly, even when the median mass is unbiased, the scatter is not because for each selection the sample is skewed towards lower masses than a mass-selected sample. Each selection leads to a different bias in secondary quantities like cool-core fraction, temperature, and gas fraction.

The circular velocity and halo mass functions of galaxies in the nearby Universe

ABSTRACT The circular velocity function (CVF) of galaxies is a fundamental test of the Lambda cold dark matter ($\Lambda$CDM) paradigm as it traces the variation of galaxy number densities with circular velocity ($v_{\rm {circ}}$), a proxy for dynamical mass. Previous observational studies of the CVF have either been based on H i-rich galaxies, or encompassed low-number statistics and probed narrow ranges in $v_{\rm {circ}}$. We present a benchmark computation of the CVF between $100\,{\text{and}}\,350\ \rm {km\ s^{-1}}$ using a sample of 3527 nearby Universe galaxies, representative for stellar masses between $10^{9.2}\,{\text{and}}\,10^{11.9} \rm {{\rm M}_{\odot }}$. We find significantly larger number densities above 150 $\rm {km\ s^{-1}}$ compared to results from H i surveys, pertaining to the morphological diversity of our sample. Leveraging the fact that circular velocities are tracing the gravitational potential of haloes, we compute the halo mass function (HMF), covering $\sim$1 dex of previously unprobed halo masses ($10^{11.7}{\!-\!}10^{12.7} \rm {{\rm M}_{\odot }}$). The HMF for our sample, representative of the galaxy population with $M_{200}\geqslant 10^{11.35} \rm {{\rm M}_{\odot }}$, shows that spiral morphologies contribute 67 per cent of the matter density in the nearby Universe, while early types account for the rest. We combine our HMF data with literature measurements based on H i kinematics and group/cluster velocity dispersions. We constrain the functional form of the HMF between $10^{10.5}-10^{15.5} \rm {{\rm M}_{\odot }}$, finding a good agreement with $\Lambda$CDM predictions. The halo mass range probed encompasses 72$\substack{+5 -6}$ per cent ($\Omega _{\rm {M,10.5-15.5}} = 0.227 \pm 0.018$) of the matter density in the nearby Universe; 31$\substack{+5 -6}$ per cent is accounted for by haloes below $10^{12.7}\rm {{\rm M}_{\odot }}$ occupied by a single galaxy.

Star-forming and Quiescent Central Galaxies Cluster Similarly: Implications for the Galaxy–Halo Connection

Abstract We measure the clustering of low-redshift SDSS galaxies as a function of stellar mass (10.0 < log (M*/M⊙) < 11.5) and specific star formation rate (sSFR) and compare the results to models of the galaxy–halo connection. We find that the auto-correlation functions of central galaxies exhibit little dependence on sSFR, with the well-known stronger clustering of quiescent galaxies mainly attributable to satellites. Because halo assembly history is known to affect distinct halo clustering, this result implies that there is little net correlation between halo assembly history and central galaxy sSFR. However, cross-correlations with satellites are stronger for quiescent centrals than star-forming centrals, consistent with quiescent centrals having more satellites in their haloes at fixed M*, as found in SDSS group catalogues. We model the galaxy–halo connection in an N-body simulation by assigning sSFRs to central galaxies in three different ways. Two of the models depend on halo assembly history (being based on halo accretion rate or concentration), while the third is independent of halo assembly history (being based on peak halo circular velocity, Vpeak, a proxy for halo mass). All three models replicate the observed auto-correlations of central galaxies, while only the Vpeak model reproduces the observed cross-correlations with satellites. This further suggests that the effects of halo assembly history may not be easily seen in auto-correlations of centrals and implies that a more complete understanding of central galaxy clustering may require more than auto-correlations of centrals alone. Additionally, the good agreement with the Vpeak model supports the idea that quiescent galaxies reside in more massive haloes than star-forming galaxies at fixed M*.

The SRG/eROSITA All-Sky Survey: Exploring halo assembly bias with X-ray-selected superclusters

Numerical simulations indicate that the clustering of dark matter halos is not only dependent on the halo masses but has a secondary dependence on other properties, such as the assembly history of the halo. This phenomenon, known as the halo assembly bias (HAB), has been found mostly on galaxy scales; observational evidence on larger scales is scarce. In this work, we propose a novel method for exploring HAB on cluster scales using large samples of superclusters. Leveraging the largest-ever X-ray galaxy cluster and supercluster samples obtained from the first SRG/eROSITA all-sky survey, we constructed two subsamples of galaxy clusters that consist of supercluster members and isolated clusters, respectively. After correcting for the selection effects on redshift, mass, and survey depth, we computed the excess in the concentration of the intracluster gas of isolated clusters with respect to supercluster members, defined as δcgas ≡ cgas, ISO/cgas, SC − 1, to investigate the environmental effect on the concentration of clusters, a sign of HAB on cluster scales. We find that the average gas mass concentration of isolated clusters is a few percent higher than that of supercluster members, with a maximum significance of 2.8σ. The result for δcgas varies with the overdensity ratio, f, in supercluster identification, cluster mass proxies, and mass and redshift ranges but remains positive in almost all the measurements. We measure slightly larger δcgas when adopting a higher f for supercluster identification. The δcgas is also higher for low-mass and low-redshift clusters. We performed weak lensing analyses to compare the total mass concentration of the two classes and find a similar trend in total mass concentration as obtained from the gas mass concentration. Our results are consistent with the prediction of HAB on cluster scales, where halos located in denser environments are less concentrated; this trend is stronger for halos with lower masses and at lower redshifts. These phenomena can be explained by the fact that clusters in denser environments, such as superclusters, have experienced more mergers than isolated clusters in their assembling history. This work paves the way to explore HAB with X-ray superclusters and demonstrates that large samples of superclusters with X-ray and weak-lensing data can advance our understanding of the evolution of the large-scale structure.

Mass calibration of DES Year-3 clusters via SPT-3G CMB cluster lensing

We measure the stacked lensing signal in the direction of galaxy clusters in the Dark Energy Survey Year 3 (DES Y3) redMaPPer sample, using cosmic microwave background (CMB) temperature data from SPT-3G, the third-generation CMB camera on the South Pole Telescope (SPT). Here, we estimate the lensing signal using temperature maps constructed from the initial 2 years of data from the SPT-3G 'Main' survey, covering 1500 deg2 of the Southern sky. We then use this lensing signal as a proxy for the mean cluster mass of the DES sample. The thermal Sunyaev-Zel'dovich (tSZ) signal, which can contaminate the lensing signal if not addressed, is isolated and removed from the data before obtaining the mass measurement. In this work, we employ three versions of the redMaPPer catalogue: a Flux-Limited sample containing 8865 clusters, a Volume-Limited sample with 5391 clusters, and a Volume&Redshift-Limited sample with 4450 clusters. For the three samples, we detect the CMB lensing signal at a significance of 12.4σ, 10.5σ and 10.2σ and find the mean cluster masses to be M 200m = 1.66±0.13 [stat.]± 0.03 [sys.], 1.97±0.18 [stat.]± 0.05 [sys.], and 2.11±0.20 [stat.]± 0.05 [sys.]×1014 M⊙, respectively. This is a factor of ∼ 2 improvement relative to the precision of measurements with previous generations of SPT surveys and the most constraining cluster mass measurements using CMB cluster lensing to date. Overall, we find no significant tensions between our results and masses given by redMaPPer mass-richness scaling relations of previous works, which were calibrated using CMB cluster lensing, optical weak lensing, and velocity dispersion measurements from various combinations of DES, SDSS and Planck data. We then divide our sample into 3 redshift and 3 richness bins, finding no significant discrepancies with optical weak-lensing calibrated masses in these bins. We forecast a 5.7% constraint on the mean cluster mass of the DES Y3 sample with the complete SPT-3G surveys when using both temperature and polarization data and including an additional ∼ 1400 deg2 of observations from the 'Extended' SPT-3G survey.

Diagnostic and prognostic value of calf circumference for sarcopenia in community-dwelling older adults

BackgroundAn age-dependent normative values of calf circumference (CC) has been recently proposed as an accessible proxy for muscle mass. However, its usefulness to estimate sarcopenia has not been assessed. The objectives of the present study were to determine if the substitution of the classical way to assess muscle mass by these values have enough diagnostic accuracy and prognostic value among older adults living in the community. MethodsData from the Toledo Study of Healthy Ageing (TSHA) were used. CC was measured using an anthropometric tape. We used two age-groups CC cut-off points: the TSHA CC median and the one proposed in the Longevity Check-up 7+ (Lookup 7+) project. Sarcopenia was defined based on the European Working Group on Sarcopenia in Older People (EWGSOP2), the Foundation for the National Institutes of Health (FNIH), and FNIH criteria standardized for our population (sFNIH). Frailty (according to the Frailty Phenotype and the Frailty Trait Scale-5) and disability (Katz index) were assessed at baseline and follow-up. Mortality and first hospitalization were also recorded. Logistic (incident frailty and worsening disability) and Cox (mortality and hospitalization) regressions were performed. Diagnostic accuracy was assessed through Kappa index, AUCs, positive and negative predictive values. Predictive ability was assessed through AUCs and integrated AUCs (IAUCs). Results1531 participants (74.8 ± 5.8 years; 45.6% men) were included in the analysis. Prevalence rates of sarcopenia were 22.7% (sFNIH), 15.0% (FNIH), and 13.9% (EWGSOP2). Using TSHA-based cut-points of CC, the prevalence of sarcopenia was 16.8% (sFNIH), 11.0% (FNIH), and 11.5% (EWGSOP2). According to LC7+-based CC cut-off points, sarcopenia prevalence was 17.6% (sFNIH), 11.9% (FNIH), and 12.4% (EWGSOP2). CC cut-off points showed low-to-moderate agreement (Kappa Index values between 0.49 and 0.69) with appendicular lean mass for the evaluation of sarcopenia. Sarcopenia identified by Lookup 7+ and TSHA CC cut-off points was associated with the adverse events examined, with similar AUCs and IAUCs than original sarcopenia definitions, and were lost after adjustment by baseline frailty, except when the original EWGSOP2 definition was used. ConclusionsUsing normalized values of CC as a criteria of muscle mass shows moderate agreement with classical criteria for diagnosing sarcopenia and offer similar predictive value in community-dwelling older adults.

#811 Effect of GLP-1 receptor agonists on the weight, urea distribution volume and blood pressure of hemodialysis (HD) patients

Abstract Background and Aims Glucagon-like-peptide-1 receptor agonists (GLP-1) drugs are a class of medications commonly used to treat type-2 diabetes. Diabetes is prevalent in almost 60% of the end stage kidney disease (ESKD) patients and an increasing number of dialysis patients use GLP-1 drugs. It is important to note that GLP-1 drugs may have additional benefits such as weight loss and potential cardiovascular benefits. However, little is known about the effects of these drugs in dialysis patients. We analysed the changes in body weight and blood pressure in hemodialysis (HD) patients who start using these drugs. We also analysed whether there are changes in patients’ urea distribution volume, a proxy of lean body mass, to understand whether these medications affect muscle mass. Method We retrospectively evaluated 236 ESKD patients who were prescribed GLP-1 drugs as part of routine clinical care in October of 2023 at clinics in a large dialysis organization. All patients received dialysis for at least 60 days before and after they started using the medication. We looked at the changes in the average post dialysis weight, urea distribution volume, and pre dialysis systolic blood pressure (pre-SBP) between the 60 days before using GLP-1 drugs (pre-GLP1 period) and 60 days after initiating the drug (post-GLP1 phase). For each metric, we performed a paired t-test to evaluate the changes between pre-GLP1 and post-GLP1. Results The average post dialysis weight pre-GLP1 was 103.98 kg and the average post dialysis weight post-GLP1 was 102.02 kg (difference: −1.96 kg, 95% CI :1.37 to 4.27, p-value <0.001). The average urea distribution volume was 36.0 L pre-GLP1, and 35.6 L post-GLP1 (difference: −0.47 L, 95% CI: −0.99 to 3.56, p-value=0.07). The mean pre-SBP was 147.83 mmHg pre-GLP1 and 149.67 mmHg post-GLP1 (difference: 1.85 mmHg, 95% CI: −5.49 to 24.93, p=0.29). Conclusion Our analysis showed a significant decrease in the average post dialysis weight of HD patients using GLP-1 drugs. While the decline in patients' urea distribution volume, which can be considered as a proxy for lean tissue mass, was not statistically significant, it may be clinically meaningful. We do not see a significant change in pre-SBP. Reductions in weight may suggest reduction in fat and muscle mass but can also be due to “regression to the mean” phenomena as patients who were on these medications tended to be larger. Further studies are necessary to evaluate this association.

The SRG/eROSITA All-Sky Survey

Clusters of galaxies can be used as powerful probes to study astrophysical processes on large scales, test theories of the growth of structure, and constrain cosmological models. The driving science goal of the SRG/eROSITA All-Sky Survey is to assemble a large sample of X-ray clusters with a well-defined selection function to determine the evolution of the mass function and, hence, the cosmological parameters. We present here a catalog of 12 247 optically confirmed galaxy groups and clusters detected in the 0.2–2.3 keV as extended X-ray sources in a 13 116 deg2 region in the western Galactic half of the sky, which eROSITA surveyed in its first six months of operation. The clusters in the sample span the redshift range 0.003 < z < 1.32. The majority (68%) of these clusters, 8361 sources, represent new discoveries without known counterparts in the literature. The mass range of the sample covers three orders of magnitude from 5 × 1012 Msun to 2 × 1015Msun. We construct a sample for cosmology with a higher purity level (~95%) than the primary sample, comprising 5259 securely detected and confirmed clusters in the 12791 deg2 common footprint of eRASS1 and the DESI Legacy Survey DR10. We characterize the X-ray properties of each cluster, including their flux, luminosity and temperature, the total mass, gas mass, gas mass fraction, and mass proxy YX. These are determined within two apertures, 300 kpc, and the overdensity radius R500, and are calculated by applying a forward modeling approach with a rigorous X-ray background treatment, K-factor, and the Galactic absorption corrections. Population studies utilizing log N-log S, the number of clusters detected above a given flux limit, and the luminosity function show overall agreement with the previous X-ray surveys after accounting for the survey completeness and purity through the selection function. The first eROSITA All-Sky Survey provides an unprecedented sample of galaxy groups and clusters selected in the X-ray band. The eRASS1 cluster catalog demonstrates the excellent performance of eROSITA for extended source detection, consistent with the pre-launch expectations for the final all-sky survey, eRASS:8.

Galaxy Quenching at the High Redshift Frontier: A Fundamental Test of Cosmological Models in the Early Universe with JWST-CEERS

We present an analysis of the quenching of star formation in massive galaxies (M * > 109.5 M ⊙) within the first 0.5–3 Gyr of the Universe’s history utilizing JWST-CEERS data. We utilize a combination of advanced statistical methods to accurately constrain the intrinsic dependence of quenching in a multidimensional and intercorrelated parameter space. Specifically, we apply random forest classification, area statistics, and a partial correlation analysis to the JWST-CEERS data. First, we identify the key testable predictions from two state-of-the-art cosmological simulations (IllustrisTNG and EAGLE). Both simulations predict that quenching should be regulated by supermassive black hole mass in the early Universe. Furthermore, both simulations identify the stellar potential (ϕ *) as the optimal proxy for black hole mass in photometric data. In photometric observations, where we have no direct constraints on black hole masses, we find that the stellar potential is the most predictive parameter of massive galaxy quenching at all epochs from z = 0–8, exactly as predicted by simulations for this sample. The stellar potential outperforms stellar mass, galaxy size, galaxy density, and Sérsic index as a predictor of quiescence at all epochs probed in JWST-CEERS. Collectively, these results strongly imply a stable quenching mechanism operating throughout cosmic history, which is closely connected to the central gravitational potential in galaxies. This connection is explained in cosmological models via massive black holes forming and growing in deep potential wells, and subsequently quenching galaxies through a mix of ejective and preventative active galactic nucleus feedback.

Halo Mass-observable Proxy Scaling Relations and Their Dependencies on Galaxy and Group Properties

Based on the DECaLS shear catalog, we study the scaling relations between halo mass (M h) and various proxies for Sloan Digital Sky Survey central galaxies, including stellar mass (M *), stellar velocity dispersion (σ *), abundance-matching halo mass (M AM), and satellite velocity dispersion (σ s), and their dependencies on galaxy and group properties. In general, these proxies all have strong positive correlations with M h, consistent with previous studies. We find that the M h–M * and M h–σ * relations depend strongly on group richness (N sat), while the M h–M AM and M h–σ s relations are independent of it. Moreover, the dependence on the star formation rate (SFR) is rather weak in the M h–σ * and M h–σ s relations, but very prominent in the other two. σ s is thus the best proxy among them, and its scaling relation is in good agreement with hydrodynamical simulations. However, estimating σ s accurately for individual groups/clusters is challenging because of interlopers and the requirement for sufficient satellites. We construct new proxies by combining M *, σ *, and M AM, and find that the proxy with 30% contribution from M AM and 70% from σ * can minimize the dependence on N sat and the SFR. We obtain the M h–supermassive black hole (SMBH) mass relation via the SMBH scaling relation and find indications for rapid and linear growth phases for the SMBH. We also find that correlations among M h, M *, and σ * change with M *, indicating that different processes drive the growth of galaxies and SMBHs at different stages.

The impact of gas accretion and AGN feedback on the scatter of the mass–metallicity relation

ABSTRACT The gas-phase metallicity of galaxies encodes important information about galaxy evolution processes, in particular star formation, feedback, outflows, and gas accretion, the relative importance of which can be extracted from systematic trends in the scatter of the mass–metallicity relation (MZR). Here, we use a sample of low-redshift (0.02 < z < 0.055) galaxies from SDSS to investigate the nature of the scatter around the MZR, the observables and physical processes causing it, and its dependence on galaxy mass. We use cold gas masses inferred from optical emission lines using the technique of Scholte & Saintonge (2023) to confirm that at fixed stellar mass, metallicity and gas mass are anticorrelated, but only for galaxies up to M* = 1010.5 M⊙. In that mass regime, we find a link between the offset of a galaxy from the MZR and halo mass, using the amplitude of the two-point correlation function as a proxy for halo mass; at fixed stellar mass, the most gas-poor galaxies reside in the most massive haloes. This observation is consistent with changes in gas accretion rates onto galaxies as a function of halo mass, with environmental effects acting on satellite galaxies also contributing. At higher stellar masses, the scatter of the MZR does no longer correlate with gas or halo mass. Instead, there is some indication of a link with AGN activity, as expected from models and simulations that metallicity is set by the interplay between gas in- and outflows, star formation, and AGN feedback, shaping the MZR and its scatter.

The RMS survey: A census of massive YSO multiplicity in the K band

ABSTRACT Close to 100 per cent of massive stars are thought to be in binary systems. The multiplicity of massive stars seems to be intrinsically linked to their formation and evolution, and massive young stellar objects (MYSOs) are key in observing this early stage of star formation. We have surveyed three samples totalling hundreds of MYSOs ($\gt 8\, \mathrm{M}_\odot$) across the Galaxy from the Red MSX Source (RMS) catalogue, using United Kingdom Infra-Red Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) and Vista Variables in the Via Lactea (VVV) point source data, and UKIRT K-band imaging to probe separations between 0.8 and 9 arcsec (approx 1000–100 000 au). We have used statistical methods to determine the binary statistics of the samples, and we find binary fractions of 64 ± 4 per cent for the UKIDSS sample, 53 ± 4 per cent for the VVV sample, and 49 ± 8 per cent for the RMS imaging sample. Also, we use the J- and K-band magnitudes as a proxy for the companion mass, and a significant fraction of the detected systems have estimated mass ratios >0.5, suggesting a deviation from the capture formation scenario which would be aligned with random IMF sampling. Finally, we find that YSOs located in the outer Galaxy have a higher binary fraction than those in the inner Galaxy. This is likely due to a lower stellar background density than observed towards the inner Galaxy, resulting in higher probabilities for visual binaries to be physical companions. It does indicate a binary fraction in the probed separation range of close to 100 per cent without the need to consider selection biases.

Muscle Mass and Serum Creatinine Concentration by Race and Ethnicity among Hemodialysis Patients.

Serum creatinine is a product of skeletal muscle metabolism. Differences in serum creatinine concentration between Black and non-Black individuals have been attributed to differences in muscle mass but have not been thoroughly examined. Furthermore, other race and ethnic groups have not been considered. If differences in body composition explain differences in serum concentration by race or ethnicity, then estimates of body composition could be used in eGFR equations rather than race. Adjustment for intracellular water (ICW) as a proxy of muscle mass among patients with kidney failure in whom creatinine clearance should minimally influence serum concentration does not explain race- and ethnicity-dependent differences. Differences in serum creatinine concentration among groups defined by race and ethnicity have been ascribed to differences in muscle mass. We examined differences in serum creatinine by race and ethnicity in a cohort of patients receiving hemodialysis in whom creatinine elimination by the kidney should have little or no effect on serum creatinine concentration and considered whether these differences persisted after adjustment for proxies of muscle mass. We analyzed data from 501 participants in the A Cohort Study to Investigate the Value of Exercise in ESKD/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESKD study who had been receiving hemodialysis for >1 year. We examined the independent associations among race and ethnicity (Black, Asian, non-Hispanic White, and Hispanic), serum creatinine, and ICW (L/m 2 ), a proxy for muscle mass, derived by whole-body multifrequency bioimpedance spectroscopy, using multivariable linear regression with adjustment for several demographic, clinical, and laboratory characteristics. We examined the association of race and ethnicity with serum creatinine concentration with and without adjustment for ICW. Black, Asian, and Hispanic patients had higher serum creatinine concentrations (+1.68 mg/dl [95% confidence interval (CI), 1.09 to 2.27], +1.61 mg/dl [95% CI, 0.90 to 2.32], and +0.83 [95% CI, 0.08 to 1.57], respectively) than non-Hispanic White patients. Overall, ICW was associated with serum creatinine concentration (0.26 mg/dl per L/m 2 ICW; 95% CI, 0.006 to 0.51) but was not statistically significantly different by race and ethnicity. Black, Asian, and Hispanic race and ethnicity remained significantly associated with serum creatinine concentration after adjustment for ICW. Among patients receiving dialysis, serum creatinine was higher in Black, Asian, and Hispanic patients than in non-Hispanic White patients. Differences in ICW did not explain the differences in serum creatinine concentration across race groups.

Galaxy cluster optical mass proxies from probabilistic memberships

ABSTRACT Robust galaxy cluster mass estimates are fundamental for constraining cosmological parameters from counts. For this reason, it is essential to search for tracers that, independent of the cluster’s dynamical state, have a small intrinsic scatter and can be easily inferred from observations. This work uses a simulated data set to focus on photometric properties and explores different optical mass proxies including richness, optical luminosity, and total stellar mass. We have developed a probabilistic membership assignment that makes minimal assumptions about the galaxy cluster properties, limited to a characteristic radius, velocity dispersion, and spatial distribution. Applying the estimator to over 919 galaxy clusters with zphot < 0.45 within a mass range of 1012.8–1015 M⊙, we obtain robust richness estimates that deviate from the median true value (from simulations) by −0.01 ± 0.12. The scatter in the mass–observable relations is $\sigma _{log_{10}(M|\mathcal {R})}=0.181 \pm 0.009$ dex for richness, $\sigma _{log_{10}(M|L_\lambda)}=0.151 \pm 0.007$ dex for optical luminosity, and $\sigma _{log_{10}(M|M_\lambda ^{*})}=0.097 \pm 0.005$ dex for stellar mass. We also discuss membership assignment, completeness and purity, and the consequences of small centre and redshift offsets. We conclude that the application of our method for photometric surveys delivers competitive cluster mass proxies.