Gas Cluster Research Articles

Redshift and Photon Energy Attenuation Constant in Vacuum

There obtained an estimate of the minimum value of the photon energy attenuation constant in vacuum α: α = 8 · 10–19 m–1 based on quantum concepts of the structure of vacuum and data on the red shift of the emitter spectra of distant galaxies. Presumably, the cosmic microwave radiation is partly the thermal vacuum radiation heated by the photon fluxes from the infinite universe. Despite the universe infinity, the sky is dark precisely due to the photon’s energy absorption from distant and ultra-distant galaxies in vacuum, and not only the photon absorption during various interactions with the gas or dust components of intergalactic clusters. Thus, the emission spectrum of these ultra-distant objects is transformed into the microwave range, which complements the intensity of thermal radiation in this range. The inconsistency of alternative explanations for the red shift is shown: the Doppler effect in the cosmological model of the expanding universe and the Big Bang, and the gravitational shift.

ICM-SHOX. I. Methodology Overview and Discovery of a Gas–Dark Matter Velocity Decoupling in the MACS J0018.5+1626 Merger

Galaxy cluster mergers are rich sources of information to test cluster astrophysics and cosmology. However, cluster mergers produce complex projected signals that are difficult to interpret physically from individual observational probes. Multi-probe constraints on the gas and dark matter (DM) cluster components are necessary to infer merger parameters that are otherwise degenerate. We present Improved Constraints on Mergers with SZ, Hydrodynamical simulations, Optical, and X-ray (ICM-SHOX), a systematic framework to jointly infer multiple merger parameters quantitatively via a pipeline that directly compares a novel combination of multi-probe observables to mock observables derived from hydrodynamical simulations. We report a first application of the ICM-SHOX pipeline to MACS J0018.5+1626, wherein we systematically examine simulated snapshots characterized by a wide range of initial parameters to constrain the MACS J0018.5+1626 merger geometry. We constrain the epoch of MACS J0018.5+1626 to the range 0–60 Myr post-pericenter passage, and the viewing angle is inclined ≈27°–40° from the merger axis. We obtain constraints for the impact parameter (≲250 kpc), mass ratio (≈1.5–3.0), and initial relative velocity when the clusters are separated by 3 Mpc (≈1700–3000 km s−1). The primary and secondary clusters initially (at 3 Mpc) have gas distributions that are moderately and strongly disturbed, respectively. We discover a velocity space decoupling of the DM and gas distributions in MACS J0018.5+1626, traced by cluster-member galaxy velocities and the kinematic Sunyaev–Zel'dovich effect, respectively. Our simulations indicate this decoupling is dependent on the different collisional properties of the two distributions for particular merger epochs, geometries, and viewing angles.

From surface to core: Comprehensive ToF-SIMS insights into pharmaceutical tablet analysis

This study presents an innovative approach to pharmaceutical analysis using time-of-flight secondary ion mass spectrometry (ToF-SIMS) to investigate tablets containing paracetamol in the solid state without the need for traditional pretreatment methods (dissolution, filtration, etc.). Employing both MS1 and MS2 ToF-SIMS spectra, signals characteristic of paracetamol and a fragmentation mechanism were assigned. Some findings challenge previous interpretations of certain ToF-SIMS signals attributed to paracetamol, highlighting the need for reevaluation. Moreover, as the sample was used without any pretreatment (a purchased tablet), which has a complex matrix, the resulting ToF-SIMS mass spectra can suffer from spectral interferences. The use of multivariate statistical analysis resulted in the assignment of unique signals for paracetamol. Additionally, ToF-SIMS imaging was utilized with high mass and lateral resolution, employing the delayed-extraction ToF analyzer mode, to image the two-dimensional distribution of species on the tablet’s surface with an emphasis on paracetamol distribution. The use of a gas cluster ion beam (GCIB) sputtering source in association with ToF-SIMS enabled the visualization of the three–dimensional distribution of species within the tablet. This thorough investigation advances knowledge regarding the characterization of paracetamol and offers the examination of pharmaceuticals without sample pretreatment with elemental and molecular-specific information.

Integrating machine learning and image processing for void fraction estimation in two-phase flow through corrugated channels

There is a substantial amount of information embedded in images of two-phase flow captured through high-speed video (HSV) or high-resolution photography. However, accurate image segmentation is necessary to unlock a meaningful analysis of the data. In this study, we discuss how to estimate the flow void fraction in chevron-type corrugated channels typical of compact plate heat exchangers (CPHE) from back-lit front-view HSV images, using machine learning (ML) algorithms and data processing techniques. A U-Net neural network was employed for image segmentation, demonstrating robust performance with evaluation metrics consistently exceeding 0.9. The binary masks (indicating gas or liquid phases) derived from segmentation were processed in MATLAB® to estimate void fraction through a 3D reconstruction algorithm of the gas cluster’s volume. In contrast to conventional void fraction estimates based on the area ratio of binary masks, this algorithm models the curvature of the liquid-vapor interface through the corrugated channel. When compared to other methods, our algorithm predicts very similar void fraction contour maps. However, the average discrepancy between our algorithm and the area-ratio approach can be as high as 80%, underscoring the importance of the processing method in analyzing the data and developing correlations. Finally, a drift flux model was introduced to predict the void fraction distribution using a two-part equation accommodating the dependency of the distribution coefficient C0 on the liquid flow rate for a corrugation Froude number Fr∼ larger than 1. The proposed model can predict the void fraction dataset with a mean average percentage error of 8.17%. In summary, U-Net’s pixel-level accuracy facilitates deep and precise post-processing of HSV images, enabling meaningful void fraction measurements. Thanks to its generality and minimal training effort requirements, the discussed methodology can be applied to estimate void fractions in various two-phase flow experiments and operating conditions.

The SRG/eROSITA All-Sky Survey: SRG/eROSITA cross-calibration with Chandra and XMM-Newton using galaxy cluster gas temperatures

Galaxy cluster gas temperatures ($T$) play a crucial role in many cosmological and astrophysical studies. However, it has been shown that $T$ measurements can significantly vary between different X-ray telescopes. These $T$ biases can propagate to several cluster applications in which $T$ can be used, such as measuring hydrostatic cluster masses and constraining the angular variation of cosmological parameters. Thus, it is important to accurately cross-calibrate X-ray instruments to account for systematic biases. In this work, we present the cross-calibration between Spectrum Roentgen Gamma/eROSITA (SRG/eROSITA) and Chandra /ACIS and between SRG/eROSITA and XMM-Newton /EPIC using for the first time a large sample of galaxy cluster $T$. To do so, we used the first eROSITA All-Sky Survey data and the preliminary extremely expanded HIgh FLUx Galaxy Cluster Sample, a large X-ray flux-limited cluster catalog. We spectroscopically measured X-ray $T$ for 186 independent cluster regions with both SRG/eROSITA and Chandra /ACIS in a self-consistent way for three energy bands: 0.7-7 keV (full), 0.5-4 keV (soft), and 1.5-7 keV (hard). We did the same with SRG/eROSITA and XMM-Newton /EPIC for 71 different cluster regions and all three bands. We find that SRG/eROSITA measures systematically lower $T$ than the other two instruments, with hotter clusters deviating more than cooler ones. For the full band, SRG/eROSITA returns 20$<!PCT!>$ and 14$<!PCT!>$ lower $T$ than Chandra /ACIS and XMM-Newton /EPIC, respectively, when the two other instruments each measure $k_ B T 3$ keV. The discrepancy respectively increases to 38<!PCT!> and 32<!PCT!> when Chandra /ACIS and XMM-Newton /EPIC each measure $k_ B T 10$ keV. On the other hand, the discrepancy becomes milder for low-$T$ galaxy groups. Moreover, a broken power law fit demonstrated that there is a break at the SRG/eROSITA- Chandra /ACIS scaling relation at $k_ B T 1.7-2.7$ keV, depending on the energy band. The soft band shows a marginally lower discrepancy compared to the full band. In the hard band, the cross-calibration of SRG/eROSITA and the other instruments show very strong differences. We tested several possible systematic biases (such as multiphase cluster gas, Galactic absorption, non-Gaussian scatter, and selection effects) to identify the reason behind the cross-calibration discrepancies, but none could significantly alleviate the tension. For now, it is most likely that the systematically lower SRG/eROSITA $T$ can be attributed to systematic effective area calibration uncertainties; however, the exact role of multiphase cluster gas in the observed $T$ discrepancies needs to be further investigated. Furthermore, we provide conversion factors between SRG/eROSITA Chandra /ACIS, and XMM-Newton /EPIC $T$ that will be beneficial for future cluster studies that combine SRG/eROSITA $T$ with data from other X-ray instruments. Finally, we also provide conversion functions between the official eRASS1 cluster catalog $T$ and the equivalent core and core-excised Chandra /ACIS and XMM-Newton /EPIC $T$.

Mapping the intracluster medium in the era of high-resolution X-ray spectroscopy

ABSTRACT High-resolution spectroscopy in soft X-rays will open a new window to map multiphase gas in galaxy clusters and probe physics of the intracluster medium (ICM), including chemical enrichment histories, circulation of matter and energy during large-scale structure evolution, stellar and black hole feedback, halo virialization, and gas mixing processes. An eV-level spectral resolution, large field of view, and effective area are essential to separate cluster emissions from the Galactic foreground and efficiently map the cluster outskirts. Several mission concepts that meet these criteria have been proposed recently, e.g. LEM, HUBS, and Super DIOS. This theoretical study explores what information on ICM physics could be recovered with such missions and the associated challenges. We emphasize the need for a comprehensive comparison between simulations and observations to interpret the high-resolution spectroscopic observations correctly. Using Line Emission Mapper (LEM) characteristics as an example, we demonstrate that it enables the use of soft X-ray emission lines (e.g. O vii/viii and Fe-L complex) from the cluster outskirts to measure the thermodynamic, chemical, and kinematic properties of the gas up to r200 and beyond. By generating mock observations with full backgrounds, analysing their images/spectra with observational approaches, and comparing the recovered characteristics with true ones from simulations, we develop six key science drivers for future missions, including the exploration of multiphase gas in galaxy clusters (e.g. temperature fluctuations, phase-space distributions), metallicity, ICM gas bulk motions and turbulence power spectra, ICM-cosmic filament interactions, and advances for cluster cosmology.

Refracted Gravity Solutions from Small to Large Scales

If visible matter alone is present in the Universe, general relativity (GR) and its Newtonian weak field limit (WFL) cannot explain several pieces of evidence, from the largest to the smallest scales. The most investigated solution is the cosmological model Λ cold dark matter (ΛCDM), where GR is valid and two dark components are introduced, dark energy (DE) and dark matter (DM), to explain the ∼70% and ∼25% of the mass–energy budget of the Universe, respectively. An alternative approach is provided by modified gravity theories, where a departure of the gravity law from ΛCDM is assumed, and no dark components are included. This work presents refracted gravity (RG), a modified theory of gravity formulated in a classical way where the presence of DM is mimicked by a gravitational permittivity ϵ(ρ) monotonically increasing with the local mass density ρ, which causes the field lines to be refracted in small density environments. Specifically, the flatter the system the stronger the refraction effect and thus, the larger the mass discrepancy if interpreted in Newtonian gravity. RG presented several encouraging results in modelling the dynamics of disk and elliptical galaxies and the temperature profiles of the hot X-ray emitting gas in galaxy clusters and a covariant extension of the theory seems to be promising.

Pressure resistance evaluation of an ultrathin SiNx membrane etched by a gas cluster ion beam

In this study, reactive etching of a SiNx free-standing membrane with a thickness of a few nanometers was performed using a gas cluster ion beam (GCIB) and the pressure resistance of the membrane with respect to its thickness was evaluated. The low-damage irradiation effect of a 7 keV GCIB in an acetylacetone (Hacac) atmosphere enabled the etching to retain its pressure resistance compared with that of 400 eV Ar+ beam irradiation. In a previous study, it was shown that irradiation of SiNx films with Ar plasma of several hundred eV causes defects in the bonding network of the Si–N bond and the network is easily oxidized. XPS measurements on SiNx films after GCIB etching with Hacac and Ar+ beam irradiation showed that the composition of the Si–O bond was smaller with GCIB irradiation compared to Ar+ beam irradiation. This indicates that GCIB etching with Hacac can suppress the formation of defects in the Si–N network, which reduces the degradation of the pressure resistance.

The FLAMINGO project: baryonic impact on weak gravitational lensing convergence peak counts

ABSTRACT Weak gravitational lensing convergence peaks, the local maxima in weak lensing convergence maps, have been shown to contain valuable cosmological information complementary to commonly used two-point statistics. To exploit the full power of weak lensing for cosmology, we must model baryonic feedback processes because these reshape the matter distribution on non-linear and mildly non-linear scales. We study the impact of baryonic physics on the number density of weak lensing peaks using the FLAMINGO cosmological hydrodynamical simulation suite. We generate ray-traced full-sky convergence maps mimicking the characteristics of a Stage IV weak lensing survey. We compare the number densities of peaks in simulations that have been calibrated to reproduce the observed galaxy mass function and cluster gas fraction or to match a shifted version of these, and that use either thermally driven or jet active galactic nucleus feedback. We show that the differences induced by realistic baryonic feedback prescriptions (typically 5–30 per cent for κ = 0.1–0.4) are smaller than those induced by reasonable variations in cosmological parameters (20–60 per cent for κ = 0.1–0.4) but must be modelled carefully to obtain unbiased results. The reasons behind these differences can be understood by considering the impact of feedback on halo masses, or by considering the impact of different cosmological parameters on the halo mass function. Our analysis demonstrates that, for the range of models we investigated, the baryonic suppression is insensitive to changes in cosmology up to κ ≈ 0.4 and that the higher κ regime is dominated by Poisson noise and cosmic variance.

Comparative study of inhibition mechanism and performance of kinetic hydrate inhibitors: Varying amide group orientation

In this work, the inhibition mechanisms of two kinetic hydrate inhibitors, poly(N-isopropyl acrylamide) (PNIPAM) and poly(N-vinyl isobutyramide) (PNVIBA), were investigated at the molecular level, and the influence of the orientation of the amide group on the inhibition performance was evaluated. The results show that two inhibitors have the similar inhibition behavior, and should have the comparable inhibition performance. However, PNIPAM is slightly better at decreasing the stability of gas clusters to inhibit hydrate nucleation, and PNVIBA is slightly better at disrupting liquid water structure and preventing hydrate nucleus from contacting with the surroundings.

Inferring the dark matter splashback radius from cluster gas and observable profiles in the FLAMINGO simulations

ABSTRACT The splashback radius, coinciding with the minimum in the dark matter radial density gradient, is thought to be a universal definition of the edge of a dark matter halo. Observational methods to detect it have traced the dark matter using weak gravitational lensing or galaxy number counts. Recent attempts have also claimed the detection of a similar feature in Sunyaev–Zel’dovich (SZ) observations of the hot intracluster gas. Here, we use the FLAMINGO simulations to investigate whether an extremum gradient in a similar position to the splashback radius is predicted to occur in the cluster gas profiles. We find that the minimum in the gradient of the stacked 3D gas density and pressure profiles, and the maximum in the gradient of the entropy profile, broadly align with the splashback feature though there are significant differences. While the dark matter splashback radius varies with specific mass accretion rate, in agreement with previous work, the radial position of the deepest minimum in the log-slope of the gas density is more sensitive to halo mass. In addition, we show that a similar minimum is also present in projected 2D pseudo-observable profiles: emission measure (X-ray), Compton-y (SZ), and surface mass density (weak lensing). We find that the latter traces the dark matter results reasonably well albeit the minimum occurs at a slightly smaller radius. While results for the gas profiles are largely insensitive to accretion rate and various observable proxies for dynamical state, they do depend on the strength of the feedback processes.

A MODEL FOR SURFACE NANORELIEF FORMATION UNDER GAS CLUSTER ION IRRADIATION

A model for the evolution of surface nanorelief under irradiation with gas cluster ions is proposed. The model is based on consideration of individual collisions of clusters with a surface. The amount of substance sputtered from the collision area and the e ciency of its redeposition onto other surface elements are determined. The performance of the model is shown when compared with experimental data. The stages of smoothing of a harmonic relief are studied. A new measure of the e ectiveness of surface smoothing is proposed.

Metal enrichment: the apex accretor perspective

The goal of this work is to devise a description of the enrichment process in large-scale structure that explains the available observations and makes predictions for future measurements. We took a spartan approach to this study, employing observational results and algebra to connect stellar assembly in star-forming halos with metal enrichment of the intra-cluster and group medium. On one hand, our construct is the first to provide an explanation for much of the phenomenology of metal enrichment in clusters and groups. It sheds light on the lack of redshift evolution in metal abundance, as well as the small scatter of metal abundance profiles, the entropy versus abundance anti-correlation found in cool core clusters, and the so-called Fe conundrum, along with several other aspects of cluster enrichment. On the other hand, it also allows us to infer the properties of other constituents of large-scale structure. We find that gas that is not bound to halos must have a metal abundance similar to that of the ICM and only about one-seventh to one-third of the Fe in the Universe is locked in stars. A comparable amount is found in gas in groups and clusters and, lastly and most importantly, about three-fifths of the total Fe is contained in a tenuous warm or hot gaseous medium in or between galaxies. We point out that several of our results follow from two critical but well motivated assumptions: 1) the stellar mass in massive halos is currently underestimated and 2) the adopted Fe yield is only marginally consistent with predictions from synthesis models and SN rates. One of the most appealing features of the work presented here is that it provides an observationally grounded construct where vital questions on chemical enrichment in the large-scale structure can be addressed. We hope that it may serve as a useful baseline for future works.

Analysis of Sustainability Report Disclosure and Sustainability Performance in Energy, Oil, and Gas Cluster BUMN Companies

Tujuan dari penelitian ini adalah untuk menganalisis pengungkapan Sustainability Report (SR) dan kinerja keberlanjutan pada PT Perusahaan Listrik Negara (Persero) dan PT Pertamina (Persero). Metode penelitian yang digunakan adalah metode kuantitatif deskriptif. Variabel yang diteliti meliputi Sustainability Report dan kinerja keberlanjutan. Hasil dari penelitian tersebut menunjukkan bahwa tingkat pengungkapan Sustainability Report (SR) PT Perusahaan Listrik Negara (PLN) dan PT Pertamina menunjukkan peningkatan yang positif. PT PLN mencatat peningkatan dari 84% pada tahun 2021 menjadi 88% pada tahun 2022. Sementara itu, PT Pertamina mencatat peningkatan dari 88% pada tahun 2021 menjadi 100% pada tahun 2022. Peningkatan ini mencerminkan komitmen dan upaya perusahaan dalam meningkatkan transparansi dan akuntabilitas terkait keberlanjutan. Penelitian ini menambah pengetahuan tentang pengungkapan SR dan kinerja keberlanjutan pada BUMN klaster energi, minyak dan gas. Hasil penelitian ini dapat meningkatkan kesadaran perusahaan akan pentingnya keberlanjutan. Perusahaan dapat menyadari bahwa kinerja keberlanjutan dapat meningkatkan reputasi perusahaan dan meningkatkan kepercayaan dari pemangku kepentingan.

Differential characteristics of the particles sputtered by gas cluster ions at elevated temperatures. Molecular dynamics simulation

The effect of the target temperature on sputtering by gas cluster ions was investigated using molecular dynamics simulation. The temperature of <111> copper target was set in range from 300 K to 1100 K, and bombarding 10 keV argon clusters had the size from 50 to 500 atoms. Sputter yield was found to increase with the temperature. The increase depended on the cluster size, and its value was much higher than it had been considered previously for nonlinear sputtering. Differential characteristics of the process, such as angular, energy, and time distributions of the sputtered atoms, as well as their initial positions, were obtained to promote understanding of the mechanisms involved. The dynamics of the collision crater size and its shape were described. The concept of temperature inside the collision area was used to explain the results.

Multimodal mass spectrometry imaging identifies cell-type-specific metabolic and lipidomic variation in the mammalian liver

Spatial single-cell omics provides a readout of biochemical processes. It is challenging to capture the transient lipidome/metabolome from cells in a native tissue environment. We employed water gas cluster ion beam secondary ion mass spectrometry imaging ([H2O]n>28K-GCIB-SIMS) at ≤3μm resolution using a cryogenic imaging workflow. This allowed multiple biomolecular imaging modes on the near-native-state liver at single-cell resolution. Our workflow utilizes desorption electrospray ionization (DESI) to build a reference map of metabolic heterogeneity and zonation across liver functional units at tissue level. Cryogenic dual-SIMS integrated metabolomics, lipidomics, and proteomics in the same liver lobules at single-cell level, characterizing the cellular landscape and metabolic states in different cell types. Lipids and metabolites classified liver metabolic zones, cell types and subtypes, highlighting the power of spatial multi-omics at high spatial resolution for understanding celluar and biomolecular organizations in the mammalian liver.

An ensemble of excited molecules collectively emits multiple-frequency real and virtual photons.

The interplay of molecules gives rise to collective phenomena absent in a single molecule. Many examples of collective phenomena have been reported as their knowledge is essential for understanding the behavior of matter. Here, we consider molecules sufficiently separated from each other to not form chemical bonds. If these molecules are excited, e.g., by a weak laser, can they concertedly relax by emitting a single high-energy photon possessing the total energy of all the relaxing molecules? We show that this concerted emission process is indeed possible. We estimate its probability and analyze its dependence on molecular properties, intermolecular distances, and relative orientations of the molecules. A numerical example on two pyridine molecules is given. The concerted emission found is a fundamental process expected to be operative in gas phase and clusters. Its true relevance lies in its intimate relationship to concerted emission of virtual photons and thus to collective energy transfer ionizing neighboring systems. The estimated rates and examples discussed of this collective intermolecular Coulombic decay shed much light on recent puzzling experiments.

High-spectral-resolution Observations of the Optical Filamentary Nebula Surrounding NGC 1275

We present new high-spectral-resolution observations (R = λ/Δλ = 7000) of the filamentary nebula surrounding NGC 1275, the central galaxy of the Perseus cluster. These observations have been obtained with SITELLE, an imaging Fourier transform spectrometer installed on the Canada–France–Hawai Telescope with a field of view of 11′×11′ , encapsulating the entire filamentary structure of ionized gas despite its large size of 80 kpc × 50 kpc. Here, we present renewed fluxes, velocities, and velocity dispersion maps that show in great detail the kinematics of the optical nebula at [S ii] λ6716, [S ii] λ6731, [N ii] λ6584, Hα (6563 Å), and [N ii] λ6548. These maps reveal the existence of a bright flattened disk-shaped structure in the core extending to r ∼10 kpc and dominated by a chaotic velocity field. This structure is located in the wake of X-ray cavities and characterized by a high mean velocity dispersion of 134 km s−1. The disk-shaped structure is surrounded by an extended array of filaments spread out to r ∼ 50 kpc that are 10 times fainter in flux, remarkably quiescent, and have a uniform mean velocity dispersion of 44 km s−1. This stability is puzzling given that the cluster core exhibits several energetic phenomena. Based on these results, we argue that there are two mechanisms that form multiphase gas in clusters of galaxies: a first triggered in the wake of X-ray cavities leading to more turbulent multiphase gas and a second, distinct mechanism, that is gentle and leads to large-scale multiphase gas spreading throughout the core.

SOCIAL NETWORK STRUCTURE AND FIRMS’ INTERNATIONALIZATION: NEW INSIGHTS FROM A WHOLE-NETWORK PERSPECTIVE

Objective: The aim of this study was to analyze the social network structure of the oil and gas (O&amp;G) cluster in Rio de Janeiro, Brazil. We explore whether internationalized firms concentrate in specific sections of the social network, and scrutinize whether internationalization is associated with a firm’s attributes and its direct and indirect network ties. Method: This research applies social network analysis, which allows us to identify dense sections, popular nodes, and strategic position. We apply partitioning techniques to determine the extent to which a firm’s internationalization is affected by those to whom it is connected. Main results: Our findings show that internationalized firms concentrate in dense sections of the network, which are characterized by high interconnectedness. Furthermore, there is indicative evidence that interaction among firms and their attributes embedded in the social network structure is associated, at least in part, with the diffusion of internationalization. Relevance / Originality: Most studies targeting the network focus on the so-called ego network. This study applies a whole-network perspective to consider popular communities and central nodes and, ultimately, show how social behavior is diffused within the social network structure. Theoretical / Methodological Contributions: Drawing upon the network theory, we emphasize interdisciplinarity to advance international business (IB) scholarship. In particular, we qualify the Uppsala model’s assumption of network/relational capability, that is, the ability to build, sustain, and coordinate relationships by demonstrating the relevance of the social network structure to the internationalization process.

Model of Surface Nanorelief Formation under Irradiation with Gas Cluster Ions

Model of Surface Nanorelief Formation under Irradiation with Gas Cluster Ions