Mass Bias Research Articles

PITSZI: Probing Intra-cluster medium Turbulence with Sunyaev-Zel'dovich Imaging. Application to the triple merging cluster MACS J0717.5+3745

Turbulent gas motions are expected to dominate the non-thermal energy budget of the intracluster medium (ICM). The measurement of pressure fluctuations from high angular resolution Sunyaev-Zel'dovich imaging opens a new avenue to study ICM turbulence, complementary to X-ray density fluctuation measures. We developed a methodological framework designed to optimally extract information on the ICM pressure fluctuation power spectrum statistics, and publicly released the associated software named PITSZI (Probing ICM Turbulence from Sunyaev-Zel'dovich Imaging). We applied this tool to the New IRAM KIDs Array (NIKA) data of the merging cluster MACS J0717.5+3745 to measure its pressure fluctuation power spectrum at high significance, and to investigate the implications for its non-thermal content. Depending on the choice of the radial pressure model and the details of the applied methodology, we measured an energy injection scale L_ inj ∼ 800 kpc. The power spectrum normalization corresponds to a characteristic amplitude reaching A_ δ P / P (k_ peak ) ∼ 0.4. These results were obtained assuming that the ICM of MACS J0717.5+3745 can be described as pressure fluctuations on top of a single (smooth) halo, and were dominated by systematics due to the choice of the radial pressure model. Using simulations, we determined that fitting a radial model to the data can suppress the observed fluctuations by up to $ ∼ 50$%, while a poorly representative radial model can induce spurious fluctuations, which we also quantified. Assuming standard scaling relations between the pressure fluctuations and turbulence, we find that MACS J0717.5+3745 presents a turbulent velocity dispersion σ_v ∼ 1200 km/s, a kinetic to kinetic plus thermal pressure fraction P_ kin / P_ kin+th ∼ 20%, and we estimate the hydrostatic mass bias to b_ HSE ∼ 0.3-0.4. Our results are in excellent agreement with alternative measurements obtained from X-ray surface brightness fluctuations, and in agreement with the fluctuations being adiabatic in nature.

H i Intensity Mapping Cross-correlation with Thermal Sunyaev–Zel’dovich Fluctuations: Forecasted Cosmological Parameter Estimation for FAST and Planck

The 21 cm emission from neutral hydrogen surveys holds great potential as a valuable method for exploring the large-scale structure (LSS) of the Universe. In this paper, we forecast for the cross-correlation between the thermal Sunyaev–Zel’dovich (SZ) fluctuations as probed by the Planck satellite and fluctuations in the H i brightness temperature as probed by the ground-based Five-hundred-meter Aperture Spherical Telescope to trace the connection between galaxy clusters and the H i LSS. Assuming that the measurement is limited by instrumental noise rather than by foreground, we estimate the potential detectability of the cross-correlation signal and the improvement in the measurement of the H i cosmic density, the hydrostatic mass bias parameter, and the universal pressure profile parameters. We obtain a constraint on the cosmic neutral hydrogen density parameter significantly to σ(ΩH I) = 1.0 × 10−6. We also find that the average halo masses contributing to the H i − y cross-power spectrum in the one-halo regime is ∼1.5 × 1014 M ⊙. Our results also show that the H i–SZ cross-correlation has great potential to probe the distribution of neutral hydrogen (H i) within halos at low redshift.

Balcerzak, Michal and Julia Kapelańska-Pręgowska, eds. 2024. Artificial Intelligence and International Human Rights Law. Developing Standards for a Changing World

This work analyzes the intersections between artificial intelligence (AI) and human rights from an international perspective. It analyzes the regulatory efforts of essential entities such as the United Nations, the Council of Europe, and the European Union. Recent initiatives that aim to establish ethical and legal standards to address the risks associated with AI are highlighted. Mass surveillance, algorithmic bias, and privacy violations stand out among these aspects. The book takes a unique approach, integrating a normative perspective with analyses of specific cases to examine the impact of artificial intelligence in key areas such as justice, health, labor rights, and privacy. It delves into challenges such as video manipulation, facial recognition regulations, and ethical conflicts in applying autonomous technologies in international settings. The book underscores the necessity of a flexible legal framework that accommodates technological advances while upholding fundamental rights. It also underscores the need to strengthen the responsibility of states and private entities to protect these rights. This volume is a fundamental reference point in the creation of international norms that ensure artificial intelligence respects human rights and proactively participates in their promotion in a globalized and constantly evolving world. Its insights are invaluable in the field of AI ethics and human rights.

Hydrostatic mass bias for galaxy groups and clusters in the FLAMINGO simulations

ABSTRACT The masses of galaxy clusters are commonly measured from X-ray observations under the assumption of hydrostatic equilibrium (HSE). This technique is known to underestimate the true mass systematically. The fiducial FLAMINGO (Full-hydro Large-scale structure simulations with All-sky Mapping for the Interpretation of Next Generation Observations) cosmological hydrodynamical simulation predicts the median hydrostatic mass bias to increase from $b_\text{HSE} \equiv (M_\text{HSE,500c}-M_\text{500c})/M_\text{500c} \approx -0.1$ to −0.2 when the true mass increases from group to cluster mass scales. However, the bias is nearly independent of the hydrostatic mass. The scatter at fixed true mass is minimum for $M_\text{500c}\sim 10^{14}~\text{M}_\odot$, where $\sigma (b_\text{HSE})\approx 0.1$, but increases rapidly towards lower and higher masses. At a fixed true mass, the hydrostatic masses increase (decrease) with redshift on group (cluster) scales, and the scatter increases. The bias is insensitive to the choice of analytic functions assumed to represent the density and temperature profiles, but it is sensitive to the goodness of fit, with poorer fits corresponding to a stronger median bias and a larger scatter. The bias is also sensitive to the strength of stellar and active galactic nucleus feedback. Models predicting lower gas fractions yield more (less) biased masses for groups (clusters). The scatter in the bias at fixed true mass is due to differences in the pressure gradients rather than in the temperature at $R_\text{500c}$. The total kinetic energies within $r_\text{500c}$ in low- and high-mass clusters are sub- and supervirial, respectively, though all become subvirial when external pressure is accounted for. Analyses of the terms in the virial and Euler equations suggest that non-thermal motions, including rotation, account for most of the hydrostatic mass bias. However, we find that the mass bias estimated from X-ray luminosity weighted profiles strongly overestimates the deviations from HSE.

G.O.Joe: A new non‐commercial software tool for the processing of LA‐ICP‐MS trace element data

A common problem of trace element measurements by LA‐ICP‐MS is the existence of interferences that cannot be resolved instrumentally. The software G.O.Joe is developed to calculate trace element mass fractions in solid samples analysed by LA‐ICP‐MS, offering the opportunity to correct for isobaric interference (including mass bias) and abundance sensitivity. Designed as a platform‐independent web application, G.O.Joe is written in the Dart programming language and runs on all web browsers supported by Flutter (i.e., Chrome, Safari, Edge, Firefox) without the need for installation. G.O.Joe is freely accessible from any computer with an internet connection to facilitate immediate data evaluation and the efficient processing of large datasets (> 400 analyses). G.O.Joe features an intuitive user interface that simplifies the selection of peak and background signals, import of instrument settings and reference material compositions to convert the measured raw signals into element mass fractions. Key functions of G.O.Joe are presented by processing the analysis of tungstates and silicates (i.e., scheelite and garnet) including specific correction methods to demonstrate their large effect on interfered masses/isotopes achievable with only little effort. This study introduces G.O.Joe as a simple, time‐efficient and flexible software to significantly improve data quality in various trace element studies utilising LA‐ICP‐MS.

Testing the Ce Limit of Mass Bias Correction Using 145Nd/142Nd as Normalizing Ratio in Radiogenic Neodymium Isotope Analysis by MC-ICP-MS.

Neodymium isotopes are a powerful geochemical tool that has widely been used in terrestrial and extraterrestrial studies. Modern multicollector inductively coupled plasma mass spectrometers (MC-ICP-MS) allow fast, accurate, and precise analysis of the radiogenic Nd isotope ratio 143Nd/144Nd. These analyses comprise relatively high instrumental mass bias that is typically corrected for using the stable 146Nd/144Nd of 0.7219 and an exponential law. The instrument is usually tuned to optimize the operating conditions for isotope analysis, but this tuning is a trade-off primarily between signal intensity, stability, and accuracy. Alternative, more effective approaches for mass bias correction have been proposed that use 145Nd/142Nd as normalizing ratio. However, one drawback of using this ratio is that the efficient removal of Ce from Nd is required to minimize the effect of isobaric interference of 142Ce on 142Nd. Here, we analyzed international Nd and rock reference materials using a Thermo Scientific Neptune Plus MC-ICP-MS to evaluate the sensitivity of 145Nd/142Nd-based mass bias correction to varying Ce/Nd and in comparison with the commonly used 146Nd/144Nd-based correction. Our results show that the corrected 143Nd/144Nd of Ce-doped JNdi-1 and Ce-containing USGS BCR-2, NOD-A-1, and NOD-P-1 reference materials are insensitive to Ce/Nd of up ~1. The correction of instrumental mass bias with 145Nd/142Nd as a normalizing ratio yields, as previously suggested, improved trueness and precision of 143Nd/144Nd data in comparison with 146Nd/144Nd-based corrections, even under high Ce/Nd of to ~1. This allows improved optimization of signal intensity during instrument tuning, which is particularly useful for natural samples with low Nd content.

THE THREE HUNDRED project: Estimating the dependence of gas filaments on the mass of galaxy clusters

Context. Galaxy clusters are located in the densest areas of the universe and are intricately connected to larger structures through the filamentary network of the cosmic web. In this scenario, matter flows from areas of lower density to higher density. As a result, the properties of galaxy clusters are deeply influenced by the filaments that are attached to them, which are quantified by a parameter known as connectivity. Aims. We explore the dependence of gas-traced filaments connected to galaxy clusters on the mass and dynamical state of the cluster. Moreover, we evaluate the effectiveness of the cosmic web extraction procedure from the gas density maps of simulated cluster regions. Methods. Using the DisPerSE cosmic web finder, we identify filamentary structures from the 3D gas particle distribution in 324 simulated regions of 30 h−1 Mpc side from THE THREE HUNDRED hydrodynamical simulation at redshifts z = 0, 1, and 2. We estimate the connectivity at various apertures for ∼3000 groups and clusters spanning a mass range from 1013 h−1 M⊙ to 1015 h−1 M⊙. Relationships between connectivity and cluster properties like radius, mass, dynamical state, and hydrostatic mass bias are explored. Results. We show that the connectivity is strongly correlated with the mass of galaxy clusters, with more massive clusters being on average more connected. This finding aligns with previous studies in the literature, both from observational and simulated datasets. Additionally, we observe a dependence of the connectivity on the aperture at which it is estimated. We find that connectivity decreases with cosmic time, while no dependencies on the dynamical state and hydrostatic mass bias of the cluster are found. Lastly, we observe a significant agreement between the connectivity measured from gas-traced and mock-galaxy-traced filaments in the simulation.

Calcium isotope evidence for the formation of early condensates in the Solar System from unmixed reservoirs with distinct nucleosynthetic origins

Calcium-aluminum rich inclusions (CAIs) are the oldest condensates in the Solar System. Previous studies have revealed that moderately heavy and trace element isotope anomalies (e.g., Ti, Sr, Mo, and Nd) in CAIs record large nucleosynthetic isotope variations compared to bulk meteorites. Calcium is a major element in CAIs that has six stable isotopes with multiple nucleosynthetic origins. As such, Ca isotopes in CAIs have been an important target of isotopic analysis since the 1970s. However, the Ca isotope compositions of CAIs measured by previous-generation mass spectrometers are less precise than recent isotopic data of heavy elements, which complicates their direct comparisons. Obtaining high-precision Ca isotopic data provides a stronger link between CAI-formation processes from nebular gas and the origin of their source materials.In this study, we report high-precision Ca isotopic compositions of CAIs, amoeboid olivine aggregates, and an Al-rich chondrule from Vigarano-type carbonaceous chondrites. The obtained µ43Ca and µ48Ca values range from +5.8 ± 1.4 to +40.2 ± 5.2 and +181.2 ± 44.8 to +743.1 ± 8.3 ppm, respectively (µXCa represents the mass bias corrected relative deviation in the XCa/44Ca ratio of the sample from a standard material in parts per million). The improved precision of our measurements reveals that the Ca isotopic compositions of CAIs vary over a narrower range than previously thought. Our precise data also show that µ43Ca and µ48Ca values in CAIs are anti-correlated, which cannot be explained by analytical artifacts such as matrix effects. Additionally, the µ43Ca and µ48Ca values of CAIs increase and decrease, respectively, with increasing Ca abundances of the inclusions. These observations suggest the presence of two distinct gaseous reservoirs from which CAIs condensed, one of which was more enriched in 43Ca but depleted in 48Ca, while the other reservoir was more depleted in 43Ca but enriched in 48Ca. Given the distinct nucleosynthetic sources of 43Ca and 48Ca, this change in isotopic signature is best understood if the two reservoirs inherited material derived from distinct nucleosynthetic sites. As such, our results suggest the presence of more than two compositionally distinct gas reservoirs for Ca isotopes in the early Solar System. If correct, this suggests that the infalling material contributing to the CAI-forming reservoirs was not fully mixed.

Forecasting Constraints from Surface Brightness Fluctuations in Galaxy Clusters

Studies of surface brightness (SB) fluctuations in the intracluster medium present an indirect estimate of turbulent pressure support and associated Mach numbers. While high-resolution X-ray spectroscopy can directly constrain line-of-sight gas motions, including those due to turbulence, such observations are relatively expensive and will be limited to nearby, bright clusters. In this respect, SB fluctuations are the most economical means to constrain turbulent motions at large cluster radii across a range of redshifts and masses. To forecast what current and future X-ray and Sunyaev–Zel’dovich facilities may achieve in SB fluctuation studies, I review and synthesize matters of accuracy and precision with respect to calculating power spectra of SB fluctuations, from which turbulent properties are derived. Balancing concerns of power spectrum accuracy and precision across a range of spatial scales, I propose the use of three annuli with [0, 0.4]R 500, [0.4, 1]R 500, and [1, 1.5]R 500. Adopting these three regions, I calculate the uncertainty in the hydrostatic mass bias, σbM , that can be achieved for various instruments in several scenarios. I find that Lynx and AtLAST are competitive in their constraints at R 500, while AtLAST should perform better when constraining σbM at R 200.

Calculation acceleration for fuel cycle simulation of molten salt reactor based on multi-group cross section method

The time-consuming issue of transport calculations is prominent in the burnup calculation of nuclear reactor. Multi-Group Cross Section (MGXS) method is an acceleration technique developed based on the characteristics of Monte Carlo simulation, which can significantly reduce the computation time required to solve a single group cross section in transportation calculations. The effectiveness of the method has been verified in the test calculations of water reactor pins. However, liquid molten salt reactors (MSRs) exhibit significant differences from conventional water reactors in terms of neutron energy spectra and fuel cycle mode. The effectiveness of the MGXS method in MSR burnup simulations remains to be validated, and targeted adjustments are required during its application. In this study, OpenMC and ORIGEN2 are coupled to develop an accelerated calculation method for MSR burnup simulations based on the MGXS approach. The reasonable grouping structure of the MGXS method is explored, and the performance of different grouping structures is tested. Results show that the transport calculation can be accelerated by an average factor of 2.4 for a single burnup zone by using MGXS method and the acceleration effect is generally independent of the grouping structure adopted. The nuclide mass bias compared to the traditional direct solution can be reduced to approximately 1% when the fuel burnup is 250MWd/kg for the LEU loading scheme with the 10000 groups structure. For the TRU loading scheme, the mass bias compared to the traditional direct solution of important nuclides (such as U-233, U-235, Pu-239 and so on) can be controlled below 0.5% at a burnup of 230 MW d/kg. The results indicate that the grouping strategy proposed in this study can achieve the adaptation of MGXS to MSRs, and the 10000 groups structure adopted in the study exhibits good accuracy.

Weak-Lensing Shear-Selected Galaxy Clusters from the Hyper Suprime-Cam Subaru Strategic Program: II. Cosmological Constraints from the Cluster Abundance

We present cosmological constraints using the abundance of weak-lensing shear-selected galaxy clusters in the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The clusters are selected on the aperture-mass maps constructed using the three-year (Y3) weak-lensing data with an area of ≈500deg 2, resulting in a sample size of 129 clusters with high signal-to-noise ratios ν≥4.7. Owing to the deep, wide-field, and uniform imaging of the HSC survey, this is by far the largest sample of shear-selected clusters, for which the selection solely depends on gravity and is free from any assumptions about the dynamical state and complex baryon physics. Informed by the optical counterparts, the shear-selected clusters span a redshift range of z≲0.7 with a median of z≈0.3. The lensing sources are securely selected at z≳0.7 with a median of z≈1.3, leading to nearly zero cluster member contamination. We carefully account for (1) the bias in the photometric redshift of sources, (2) the bias and scatter in the weak-lensing mass using a simulation-based calibration, and (3) the measurement uncertainty that is directly estimated on the aperture-mass maps using an injection-based method developed in a companion paper (Chen et al. submitted). In a blind analysis, the fully marginalized posteriors of the cosmological parameters are obtained as Ωm=0.50−0.24+0.28, σ8=0.685−0.088+0.161, Ŝ8≡σ8(Ωm/0.3)0.25=0.835−0.044+0.041, and σ8Ωm/0.3=0.993−0.126+0.084 in a flat ΛCDM model. We compare our cosmological constraints with other studies, including those based on cluster abundances, galaxy-galaxy lensing and clustering, and Cosmic Microwave Background observed by Planck, and find good agreement at levels of ≲2σ. [abridged]

Cosmological constraints from the Planck cluster catalogue with new multi-wavelength mass calibration from Chandra and CFHT

We provide a new scaling relation between $Y_ SZ $, the integrated Sunyaev-Zeldovich signal and $M_ Y_ X $, the cluster mass derived from X-ray observations, using a sample of clusters from the Planck Early Sunyaev-Zeldovich (ESZ) catalogue observed in X-rays by Chandra and compare it to the results of the Planck collaboration obtained from XMM-Newton observations of a subsample of the ESZ. We calibrated a mass bias on a subset of the Planck cosmological cluster sample using published weak-lensing data from the Canadian Cluster Cosmology Project (CCCP) and Multi Epoch Nearby Cluster Survey (MENeaCS), for the new scaling relation as well as that from the Planck collaboration. We propose a novel method to account for selection effects and find a mass bias of $(1-b)=0.89 for the Chandra -calibrated scaling relation, and $(1-b)=0.76 for the XMM-Newton -calibrated scaling relation. We applied the scaling relations we derived to the full Planck cosmological cluster sample and obtain new constraints on the cosmological parameters. We find identical constraints regardless of the X-ray sample used, with $ and $S_8 We also provide constraints with a redshift evolution of the scaling relation fitted from the data instead of fixing it to the self-similar value. We find a redshift evolution significantly deviating from the self-similar value, leading to a higher value of $S_8=0.81 We compare our results to those from various cosmological probes, and find that our $S_8$ constraints are competitive with the tightest constraints from the literature. When assuming a self-similar redshift evolution, our constraints are in agreement with most late-time probes and in tension with constraints from the cosmic microwave background (CMB) primary anisotropies. When relaxing the assumption of redshift evolution and fitting it to the data, we find no significant tension with results from either late-time probes or the CMB.

Relativistic SZ temperatures and hydrostatic mass bias for massive clusters in the FLAMINGO simulations

ABSTRACT The relativistic Sunyaev-Zel’dovich (SZ) effect can be used to measure intracluster gas temperatures independently of X-ray spectroscopy. Here, we use the large-volume FLAMINGO simulation suite to determine whether SZ y-weighted temperatures lead to more accurate hydrostatic mass estimates in massive ($M_{\rm 500c} \gt 7.5\times 10^{14}\, {\rm M}_{\odot }$) clusters than when using X-ray spectroscopic-like temperatures. We find this to be the case, on average. The median bias in the SZ mass at redshift zero is $\left\langle b \right\rangle \equiv 1-\left\langle M_{\rm 500c,hse}/M_{\rm 500c,true} \right\rangle = -0.05 \pm 0.01$, over 4 times smaller in magnitude than the X-ray spectroscopic-like case, $\left\langle b \right\rangle = 0.22 \pm 0.01$. However, the scatter in the SZ bias, $\sigma _{b} \approx 0.2$, is around 40 per cent larger than for the X-ray case. We show that this difference is strongly affected by clusters with large pressure fluctuations, as expected from shocks in ongoing mergers. Selecting the clusters with the best-fitting generalized NFW pressure profiles, the median SZ bias almost vanishes, $\left\langle b \right\rangle = -0.009 \pm 0.005$, and the scatter is halved to $\sigma _{b} \approx 0.1$. We study the origin of the SZ/X-ray difference and find that, at $R_{\rm 500c}$ and in the outskirts, SZ weighted gas better reflects the hot, hydrostatic atmosphere than the X-ray weighted gas. The SZ/X-ray temperature ratio increases with radius, a result we find to be insensitive to variations in baryonic physics, cosmology, and numerical resolution.

Multimodal Resonances of a Rectangular Planar Dielectric Elastomer Actuator and Its Application in a Robot with Soft Bristles.

Inspired by the fact that flying insects improve their power conversion efficiency through resonance, many soft robots driven by dielectric elastomer actuators (DEAs) have achieved optimal performance via first-order modal resonance. Besides first-order resonance, DEAs contribute to multiple innovative functions such as pumps that can make sounds when using multimodal resonances. This study presents the multimodal resonance of a rectangular planar DEA (RPDEA) with a central mass bias. Using a combination of experiments and finite element modeling (FEM), it was discerned that under a prestretch of 1.0 × 1.1, the first-, second-, and third-order resonances corresponded to vertical vibration, rotation along the long axis, and rotation along the short axis, respectively. In first-order resonance, superharmonic, harmonic, and subharmonic responses were activated, while only harmonic and subharmonic responses were observed in the second- and third-order resonances. Further investigations revealed that prestretching tended to inhibit third-order resonance but could elevate the resonance frequencies of the first and second orders. Conveniently, both the experimental and FEM results showed that the frequencies and amplitudes of the multimodal resonances could be tuned by adjusting the amplitudes of the excitation signals, referring to the direct current (DC) amplitude and alternating current (AC) amplitude, respectively. Moreover, instead of linear vibration, we found another novel approach that used rotation vibration to drive a robot with soft bristles via hopping locomotion, showcasing a higher speed compared to the first-order resonance in our robot.

An Analytical Method for Quantification of Sn Isotope Variations in Geological Materials Using MC‐ICP‐MS

A robust analytical method is presented here, for measurements of Sn isotope variations with high precision using a multi‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS). A silicate rock dissolution procedure was used, together with means to remove organic matter introduced by the resin during ion‐exchange chromatography. The two‐stage ion exchange chromatography efficiently isolates Sn from the matrix and isobarically interfering elements, from samples with variable Sn mass fractions (~ 0.03 to 7 μg g−1). A double spike technique was also implemented to correct any secondary mass bias induced during sample processing and isotope ratio measurements. An intermediate precision (2s) of ± 0.47 was obtained for ε122/118Sn (using internal normalisation; n = 70 over a period of 29 months), ± 0.021‰ for δ122/118Sn (using double spike; n = 176 over a period of 29 months) and ± 0.059‰ for δ122/118Sn (using Sb doping; n = 34 over a period of 4.5 months) for the Sn standard solution, NIST SRM 3161a (Lot# 140917). The δ122/118SnNIST SRM 3161a of eleven geological reference materials are reported for the first time (BIR‐1a, BRP‐1, DTS‐2b, ECRM 782‐1, JP‐1, OKUM, QLO‐1a, RGM‐2, SGR‐1b, STM‐2 and UB‐N), with five others (AGV‐2, BCR‐2, BHVO‐2, GSP‐2 and W‐2a) showing similar results to previous studies, generally with improved precision. The intermediate precision (2s) of replicate dissolutions of ten RMs (AGV‐2, BCR‐2, BHVO‐2, BIR‐1a, DTS‐2b, GSP‐2, OKUM, SGR‐1b, STM‐2 and W‐2a) varied from 0.003 to 0.054‰. Typical repeatability precision (2SE) of individual measurements of these ten RMs over multiple measurement sessions varied from 0.031 to 0.297‰ (with 120Sn+ beam intensity < 2.37 V) and 0.017 to 0.025‰ (with 120Sn+ beam intensity > 2.37 V).

Accuracy Improvement in the LA‐MC‐ICP‐MS Measurement of 87Sr/86Sr in Bioapatite Using Dentin of Carcharinus leucas (Bull shark) to Estimate 87Rb/85Rb Instrument Induced Fractionation

In situ 87Sr/86Sr microanalysis in bioapatite using laser ablation (LA‐)MC‐ICP‐MS is an essential tool for provenance studies, as enamel tissue build‐up records the regional Sr isotopic composition of ingested food and water sources. Several factors hamper the acquisition of reliable and precise 87Sr/86Sr data: isobaric interferences, elemental and isotopic fractionation of Rb and Sr, and the lack of certified reference materials. Here we thoroughly characterise several teeth from Carcharinus leucas (Bull shark) for the spatial distribution of Sr and Rb mass fraction by LA‐ICP‐Q‐MS, and their 87Sr/86Sr ratio by solution MC‐ICP‐MS, MC‐TIMS and LA‐MC‐ICP‐MS, and which were used subsequently as a reference material during laser ablation measurement of Sr isotope ratios in bioapatite. We establish a protocol to estimate the 85Rb/87Rb mass bias from the analysis of shark teeth that demonstrates that the common assumption of equal Sr and Rb instrument induced fractionation can lead to a systematic bias in 87Sr/86Sr isotope ratios. Using the shark teeth as an "external" reference material to measure βRb yielded 87Sr/86Sr compositions in unknown samples that are within approximately ‐42 ppm to +66 ppm of expected values, instead of approximately ‐50 ppm to +190 ppm if assuming βRb = βSr. Finally, this methodology was tested on fossil gomphotherid (Rhynchotherium sp.) enamel, allowing us to make preliminary inferences about its palaeobiogeography.

Weak lensing mass bias and the alignment of centre proxies

ABSTRACT Galaxy cluster masses derived from observations of weak lensing suffer from a number of biases affecting the accuracy of mass-observable relations calibrated from such observations. In particular, the choice of the cluster centre plays a prominent role in biasing inferred masses. In the past, empirical miscentring distributions have been used to address this issue. Using hydrodynamic simulations, we aim to test the accuracy of weak lensing mass bias predictions based on such miscentring distributions by comparing the results to mass biases computed directly using intracluster medium (ICM)-based centres from the same simulation. We construct models for fitting masses to both centred and miscentred Navarro–Frenk–White profiles of reduced shear, and model the resulting distributions of mass bias with normal and lognormal distributions. We find that the standard approach of using miscentring distributions leads to an overestimation of cluster masses at levels of between 2 per cent and 6 per cent when compared to the analysis in which actual simulated ICM centres are used, even when the underlying miscentring distributions match in terms of the miscentring amplitude. While we find that neither lognormal nor normal distributions are generally reliable for accurately modelling the shapes of the mass bias distributions, both models can serve as reasonable approximations in practice.

Impact of Assimilating Radar Solid Precipitation Data in the Canadian Precipitation Analysis System

Abstract The Canadian Precipitation Analysis (CaPA) system provides near-real-time precipitation analyses over Canada by combining observations with short-term numerical weather prediction forecasts. CaPA’s snowfall estimates suffer from the lack of accurate solid precipitation measurements to correct the first-guess estimate. Weather radars have the potential to add precipitation measurements to CaPA in all seasons but are not assimilated in winter due to radar snowfall estimate imprecision and lack of precipitation gauges for calibration. The main objective of this study is to assess the impact of assimilating Canadian dual-polarized radar-based snowfall data in CaPA to improve precipitation estimates. Two sets of experiments were conducted to evaluate the impact of including radar snowfall retrievals, one set using the high-resolution CaPA (HRDPA) with the currently operational quality control configuration and another increasing the number of assimilated surface observations by relaxing quality control. Experiments spanned two winter seasons (2021 and 2022) in central Canada, covering part of the entire CaPA domain. The results showed that the assimilation of radar-based snowfall data improved CaPA’s precipitation estimates 81.75% of the time for 0.5-mm precipitation thresholds. An increase in the probability of detection together with a decrease in the false alarm ratio suggested an improvement of the precipitation spatial distribution and estimation accuracy. Additionally, the results showed improvements for both precipitation mass and frequency biases for low precipitation amounts. For larger thresholds, the frequency bias was degraded. The results also indicated that the assimilation of dual-polarization radar data is beneficial for the two CaPA configurations tested in this study.

Simulating the LOcal Web (SLOW)

Context. This is the second paper in a series presenting the results from a 500 h−1Mpc large constrained simulation of the local Universe (SLOW). The initial conditions for this cosmological hydro-dynamical simulation are based on peculiar velocities derived from the CosmicFlows-2 catalog. The simulation follows cooling, star formation, and the evolution of super-massive black holes. This allows one to directly predict observable properties of the intracluster medium (ICM) within galaxy clusters, including X-ray luminosity, temperatures, and the Compton-y signal. Aims. Comparing the properties of observed galaxy clusters within the local Universe with the properties of their simulated counterparts enables us to assess the effectiveness of the initial condition constraints in accurately replicating the mildly nonlinear properties of the largest, collapsed objects within the simulation. Methods. Based on the combination of several, publicly available surveys we compiled a sample of galaxy clusters within the local Universe, of which we were able to cross-identify 46 of them with an associated counterpart within the SLOW simulation. We then derived the probability of the cross identification based on mass, X-ray luminosity, temperature, and Compton-y by comparing it to a random selection. Results. Our set of 46 cross-identified local Universe clusters contains the 13 most massive clusters from the Planck SZ catalog as well as 70% of clusters with M500 larger than 2 × 1014 M⊙. Compared to previous constrained simulations of the local volume, we found in SLOW a much larger amount of replicated galaxy clusters, where their simulation-based mass prediction falls within the uncertainties of the observational mass estimates. Comparing the median observed and simulated masses of our cross-identified sample allows us to independently deduce a hydrostatic mass bias of (1 − b)≈0.87. Conclusions. The SLOW constrained simulation of the local Universe faithfully reproduces numerous fundamental characteristics of a sizable number of galaxy clusters within our local neighborhood, opening a new avenue for studying the formation and evolution of a large set of individual galaxy clusters as well as testing our understanding of physical processes governing the ICM.

Reliability Evaluation for Mercury Stable Isotope Ratio Measurement by MC-ICP/MS

This study assessed the reliability of Mercury (Hg) stable isotope ratio measurements using MC-ICP/MS hyphenated with three different systems: wet plasma, dry plasma, and a cold vapor generator (CVG). Precision measurements using wet plasma improved with concentration, showing a range of 0.4 - 10.0% at 100 µg/L, with corresponding accuracy from 0.0 – 0.4%. By contrast, dry plasma demonstrated precision between 0.02 - 2.2% at 10 µg/L for 202/198Hg, with accuracy ranging from 1.2 - 1.4%. The CVG system, however, displayed significantly enhanced accuracy, from 0.2% for 199/198Hg to 0.9% for 204/198Hg at 0.1 µg/L. The study also incorporated a mass bias correction using a thallium (NIST 997 standard) internal spike, emphasizing the importance of maintaining a total Hg beam above 0.5 V to ensure measurement precision and accuracy. The findings suggest that the CVG method is most suitable for environmental samples with trace Hg concentrations, while both dry and wet plasma systems can serve effectively at higher concentrations (≥ 100 µg/L), given their analytical convenience and performance.