Mass Parameters Research Articles

A 22 Billion M⊙ Black Hole in Holmberg 15A with Keck KCWI Spectroscopy and Triaxial Orbit Modeling

Abstract Holmberg 15A (H15A), the brightest cluster galaxy of A85, has an exceptionally low central surface brightness even among local massive elliptical galaxies with distinct stellar cores, making it exceedingly challenging to obtain high-quality spectroscopy to detect a supermassive black hole (SMBH) at its center. Aided by the superb sensitivity and efficiency of KCWI at the Keck II Telescope, we have obtained spatially resolved stellar kinematics over a ∼100″ × 100″ contiguous field of H15A for this purpose. The velocity field exhibits a low-amplitude (∼20 km s−1) rotation along a kinematic axis that is prominently misaligned from the photometric major axis, a strong indicator that H15A is triaxially shaped with unequal lengths for the three principal axes. Using 2500 observed kinematic constraints, we perform extensive calculations of stellar orbits with the triaxial Schwarzschild code, TriOS, and search over ∼40,000 galaxy models to simultaneously determine the mass and intrinsic 3D shape parameters of H15A. We determine a ratio of p = 0.89 for the middle-to-long principal axes and q = 0.65 for the short-to-long principal axes. Our best estimate of the SMBH mass, M BH = ( 2.1 6 − 0.18 + 0.23 ) × 1 0 10 M ⊙ , makes H15A—along with NGC 4889—the galaxy hosting the most massive SMBHs known in the local Universe. Both SMBHs lie significantly above the mean M BH–σ scaling relation. Repeating the orbit modeling with the axisymmetrized version of TriOS produces worse fits to the KCWI kinematics and increases M BH to (2.55 ± 0.20) × 1010 M ⊙, which is still significantly below the M BH = (4.0 ± 0.8) × 1010 M ⊙ reported in a prior axisymmetric study of H15A.

Appraising constrained second-order power corrections in HQET with Λb→Λclν

We derive the Λb→Λc form factors for the Standard Model and beyond at second order in heavy quark effective theory, applying the recently proposed residual chiral expansion to reduce the set of unknown subsubleading hadronic functions to a single, highly constrained function, that is fully determined by hadron mass parameters at zero recoil. We fit a form factor parametrization based on these results to all available lattice QCD predictions and experimental data. We find that the constrained and predictive structure of the form factors under the residual chiral expansion is in excellent agreement with lattice QCD predictions and experimental data, as well as prior heavy-quark-effective-theory-based fits. Published by the American Physical Society 2025

Gravity from Pre-geometry

Abstract The gravitational interaction, as described by the Einstein–Cartan theory, is shown to emerge as the by-product of the spontaneous symmetry breaking of a gauge symmetry in a pre-geometric four-dimensional spacetime. Starting from a formulation a ` la Yang–Mills on an SO ( 1 , 4 ) or SO ( 3 , 2 ) principal bundle and not accounting for a spacetime metric, the Einstein–Hilbert action is recovered after the identification of the effective spacetime metric and spin connection for the residual SO ( 1 , 3 ) gauge symmetry of the spontaneously broken phase—i.e. the stabiliser of the SO ( 1 , 4 ) or SO ( 3 , 2 ) gauge group. Thus, the two fundamental tenets of general relativity, i.e. diffeomorphism invariance and the equivalence principle, can arise from a more fundamental gauge principle. The two mass parameters that characterise Einstein gravity, namely the Planck mass and the cosmological constant, are likewise shown to be emergent. The phase transition from the unbroken to the spontaneously broken phase is expected to happen close to the Planck temperature. This is conjectured to be dynamically driven by a scalar field that implements a Higgs mechanism, hence providing mass to new particles, with consequences for cosmology and high-energy physics. The couplings of gravity to matter are discussed after drawing up a dictionary that interconnects pre-geometric and effective geometric quantities. In the unbroken phase where the fundamental gauge symmetry is restored, the theory is potentially power-counting renormalisable without matter, offering a novel path towards a UV completion of Einstein gravity.

The Effect of Anti-Activin Receptor Type IIA and Type IIB Antibody on Muscle, Bone and Blood in Healthy and Osteosarcopenic Mice.

Anti-Activin Receptor Type IIA and Type IIB antibody (αActRIIA/IIB ab) is a recently developed drug class that targets the activin receptor signalling pathway. Inhibition of receptor ligands (activins, myostatin, growth differentiation factor 11, etc.) can lead to skeletal muscle hypertrophy, bone formation, and increased haematopoiesis. Despite the αActRIIA/IIB ab, bimagrumab, having progressed to clinical trials, two crucial questions about αActRIIA/IIB ab therapy remain: Does αActRIIA/IIB ab influence bone metabolism and bone strength similarly to its generic classmates (activin receptor-based ligand traps)? Does αActRIIA/IIB ab affect red blood cell parameters, thereby increasing the risk of thromboembolism, similar to its generic classmates? Therefore, the aim of the present study was to investigate the therapeutic potential of αActRIIA/IIB ab in a mouse model of concurrent sarcopenia and osteopenia and to investigate the effect on bone and haematopoiesis in more detail. In C57BL/6JRj mice, combined sarcopenia and osteopenia were induced locally by injecting botulinum toxin A into the right hindlimb, resulting in acute muscle paresis. Immediately after immobilization, mice received twice-weekly intraperitoneal injections with αActRIIA/IIB ab (10 mg/kg) for 21 days, after which they were sacrificed. Muscle mass, skeletal muscle fibre size and Smad2 expression were analysed in the rectus femoris and gastrocnemius muscles. Bone mass and bone microstructure were analysed in the trabecular bone at the distal femoral metaphysis, while the cortical bone was analysed at the femoral mid-diaphysis. In a substudy, the effect on haematopoiesis was explored 2 and 7 days after a single αActRIIA/IIB ab (30 mg/kg) injection in C57BL/6JRj mice. αActRIIA/IIB ab caused a large increase in muscle mass in both healthy (+21%) and immobilized (sarcopenic and osteopenic) (+12%) mice. Furthermore, αActRIIA/IIB ab increased trabecular bone (bone volume fraction) for both healthy (+65%) and immobilized (+44%) mice. For cortical bone, αActRIIA/IIB ab caused a small, but significant, increase in bone area (+6%) for immobilized mice, but not for healthy mice. Treatment with αActRIIA/IIB ab did not change red blood cell count, haemoglobin concentration or mean cell volume after either 2 or 7 days. Treatment with αActRIIA/IIB ab caused a significant increase in both skeletal muscle mass and bone parameters in both healthy and immobilized mice, suggesting a potential in the treatment of concurrent osteopenia and sarcopenia. Interestingly, the bone anabolic effect of the treatment was much more pronounced on trabecular bone than on cortical bone. There was no pronounced effect of short-term treatment on haematopoiesis.

Heat and Mass Transfer in Shrimp Hot-Air Drying: Experimental Evaluation and Numerical Simulation

Shrimp is one of the most popular and widely consumed seafood products worldwide. It is highly perishable due to its high moisture content. Thus, dehydration is commonly used to extend its shelf life, mostly via air drying, leading to a temperature increase, moisture removal, and matrix shrinkage. In this study, a mathematical model was developed to describe the changes in moisture and temperature distribution in shrimp during hot-air drying. The model considered the heat and mass transfer in an irregular-shaped computational domain and was solved using the finite element method. Convective heat and mass transfer coefficients (57.0–62.9 W/m2∙K and 0.007–0.008 m/s, respectively) and the moisture effective diffusion coefficient (6.5 × 10−10–8.5 × 10−10 m2/s) were determined experimentally and numerically. The shrimp temperature and moisture numerical solution were validated using a cabinet dryer with a forced air circulation at 60 and 70 °C. The model predictions demonstrated close agreement with the experimental data (R2≥ 0.95 for all conditions) and revealed three distinct drying stages: initial warming up, constant drying rate, and falling drying rate at the end. Initially, the shrimp temperature increased from 25 °C to around 46 °C and 53 °C for the process at 60 °C and 70 °C. Thus, it presented a constant drying rate, around 0.04 kg/kg min at 60 °C and 0.05 kg/kg min at 70 °C. During this stage, the process is controlled by the heat transferred from the surroundings. Subsequently, the internal resistance to mass transfer becomes the dominant factor, leading to a decrease in the drying rate and an increase in temperatures. A numerical analysis indicated that considering the irregular shape of the shrimp provides more realistic moisture and temperature profiles compared to the simplified finite cylinder geometry. Furthermore, a sensitivity analysis was performed using the validated model to assess the impact of the mass and heat transfer parameters and relative humidity inside the cavity on the drying process. The proposed model accurately described the drying, allowing the further evaluation of the quality and safety aspects and optimizing the process.

Searches for long-lived dark photons at proton accelerator experiments

A systematic and unified analysis of the capability of lifetime frontier experiments to probe the parameter space of hypothetical long-lived particles is crucial for defining the targets of future searches. However, such a comprehensive study has not yet been conducted for dark photons—hypothetical massive particles that kinetically mix with Standard Model photons. Existing studies often rely on outdated assumptions about dark photon phenomenology, leading to inaccurate calculations of the parameter space, including regions already excluded or relevant for future experiments. In this paper, we present a comprehensive calculation of the parameter space for GeV-scale dark photons and light dark matter accessible to lifetime frontier experiments. Our analysis highlights how theoretical uncertainties in dark photon phenomenology can significantly impact experimental sensitivity across coupling and mass parameters. To facilitate further investigation, we provide these results in a publicly accessible form, incorporating updated dark photon phenomenology into the event generator ensalc. Published by the American Physical Society 2025

Gauge-Invariant Perturbation Theory on the Schwarzschild Background Spacetime Part II: Even-Mode Perturbations

This is the Part II paper of our series of papers on a gauge-invariant perturbation theory on the Schwarzschild background spacetime. After reviewing our general framework of the gauge-invariant perturbation theory and the proposal of gauge-invariant treatments for l=0,1-mode perturbations on the Schwarzschild background spacetime in the Part I paper, we examine the linearized Einstein equations for even-mode perturbations. We discuss the strategy to solve the linearized Einstein equations for these even-mode perturbations including l=0,1 modes. Furthermore, we explicitly derive the l=0,1-mode solutions to the linearized Einstein equations in both the vacuum and the non-vacuum cases. We show that the solutions for l=0-mode perturbations includes the additional Schwarzschild mass parameter perturbation, which is physically reasonable. Then, we conclude that our proposal of the resolution of the l=0,1-mode problem is physically reasonable due to the realization of the additional Schwarzschild mass parameter perturbation and the Kerr parameter perturbation in the Part I paper.

Circular motion and chaos-bound violation for dyonic global monopole spacetime surrounded by a perfect fluid

In this paper, we investigate the circular motion and chaotic behavior of charged particles in the dyonic global monopole spacetime surrounded by a perfect fluid. We classified the black hole into three special regimes: dark matter, dust, and radiation. We precisely calculated the Lyapunov exponent for each regime as an eigenvalue of the Jacobian matrix. We examine, through numerical and graphical analysis, the circular motion and chaos bound violation across all the regimes. In the dark matter regime, stable orbits conform to the chaos bound. Even though the bound brings orbits with small charges and those far from the event horizon closer, they never violate it. In the dust regime, there can be more than one orbit for a fixed mass, charge, topological defect, and fluid parameter, especially when the angular momentum is small. At this point, the orbits are unstable, and those that are closer to the event horizon violate the bound. Similarly, in the radiation regime, orbits that are closer to the event horizon are unstable and chaotic, especially with greater angular momentum. In fact, regardless of the charge, topological defect, and fluid parameter, all orbits, whether they are far from or close to the horizon, become unstable and violate the bound when the angular momentum is significantly large.

Antiosteoporosis and Bone Protective Effect of Phyllanthin Against Glucocorticoid-induced Osteoporosis in Rats via Alteration of HO-1/Nrf2 and RANK/RANKL/OPG Pathway.

: SD rats were used in this study and subcutaneous administration of DEX (3 mg/kg) was used for the induction of osteoporosis and rats were treated with phyllanthin and alendronate for 12 weeks. The body weight, femur mass, length, hormones, nutrients, antioxidant, cytokines and bone parameters were estimated. The mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG were estimated. : Phyllanthin treatment significantly (p < 0.001) improved the body weight, femur mass and femur length. Phyllanthin significantly (p < 0.001) altered the level of hormones estrodiol, PTH; nutrients such as calcium, phosphorus, magnesium; Bone mineral content (BMC) and bone mineral density (BMD); Bone formation marker like ALP, TRAP, osteocalcin, β-CTX, BGP, cathepsin K, DPD; Bone parameters viz., Tb.N, BV/TV, Tb.sp, BS/BV, Tb.Th; Bone structure analysis includes maximum load, energy, stiffness, maximum stress, young's modules; oxidative stress parameters such as TBARS, CAT, GPx, GSH, GR; cytokines such as TNF-α, IL-1β, IL-6, IL-10 and antioxidant marker such as HO-1 and Nrf2. Phyllanthin significantly (P < 0.001) altered the mRNA expression of HO-1, Nrf2, RANK, RANKL and OPG. : On the basis of result, we can say that phyllanthin exhibited the antiosteoporosis effect against glucocorticoid-induced osteoporosis in rats via alteration of HO-1/Nrf2 and RANK/RANKL/OPG pathway.

Prognostic value of CT-based skeletal muscle and adipose tissue mass and quality parameters in patients with liver metastases and intrahepatic cholangiocarcinoma undergoing Yttrium-90 radioembolization.

To investigate baseline patient characteristics associated with the risk of computed tomography (CT)-based sarcopenia and assess whether sarcopenia and other morphometric parameters influence survival outcomes in patients with liver metastases and cholangiocarcinoma after Yttrium-90 radioembolization. We retrospectively analyzed 120 cancer patients (mean age, 62 ± 13.3 years, 61 men) who underwent preprocedural CT. Skeletal muscle index (SMI) was measured at the L3 vertebral level to identify sarcopenia. The Cox proportional hazard model was performed to assess the prognostic value of the variables, and Kaplan-Meier analysis with log-rank text was used for overall survival (OS) assessment. Sarcopenia was diagnosed in 70 patients (58.3%). The multivariate regression analysis demonstrated that malesex, body mass index (BMI), visceral fat radiation attenuation (VFRA), skeletal muscle radiation attenuation (SMRA), and subcutaneous fat radiation attenuation (SFRA) were associated with the incidence of sarcopenia with the odds ratio of 8.81 (95% CI, 2.09-37.1, p = 0.003), 0.64 (95% CI, 0.48-0.85, p = 0.002), 1.23 (95% CI, 1.06-1.42, p = 0.006), 0.79 (95% CI, 0.69-0.91, p = 0.001) and 0.84 (95% CI, 0.76-0.93, p = 0.001), respectively. Age, skeletal muscle index, and tumor subtypes were independent prognostic factors for OS with the hazard ratio of 1.03 (95% CI, 1.01-1.05, p = 0.01), 0.92 (95% CI, 0.86-0.99, p = 0.021) and 2.09 (95% CI, 1.31-3.33 p = 0.002), respectively. In patients with intrahepatic cholangiocarcinoma, median OS was significantly longer in thenon-sarcopenic group than in the sarcopenic patient (25.9 versus 6.5 months, p = 0.029). Malesex, BMI, VFRA, SMRA, and SFRA were associated with the incidence of sarcopenia. SMI value could be used as a biomarker for OS in patients treated with Yttrium-90 radioembolization. Question The prognostic significance of CT-based sarcopenia and other morphometric parameters in patients with liver metastases and cholangiocarcinoma undergoing Yttrium-90 radioembolization remains unclear. Findings A high skeletal muscle index has been identified as an independent protective factor for overall survival in cancer patients treated with Yttrium-90 radioembolization. Clinical relevance The negative impact of CT-based sarcopenia has been confirmed in the context of Yttrium-90 radioembolization. Clinicians should strive to prevent the progression of sarcopenia or maintain skeletal muscle index in perioperative management.

New models of quintessential inflation featuring plateau and hilltop potentials

We introduce a new class of hilltop and plateau potentials which can successfully unify inflation and dark energy resulting in quintessential inflation (QI). Interestingly these new potentials are related through an inverse transformation. Namely, if V(ϕ)=V0v(ϕ) is a plateau potential then the inverse potential V(ϕ)=V0v(ϕ)-1 describes hilltop QI. A simple example is provided by the KKLT-inspired potential v(ϕ)=M2n+ϕ2nN2n+ϕ2n. When M/N≪1 this potential describes plateau QI, while its inverse, v(ϕ)-1 describes hilltop QI. Other simple models of QI arise for the class of potentials V(ϕ)∼exp∓f(ϕ), where the − (+) sign is associated with a plateau (hilltop). A key feature of this new class of QI models is the near absence of small dimensionless parameters, or small mass parameters (relative to the energy scale of the Standard Model of particle physics) – which are usually associated with the presence of dark energy. A forecast for the gravitational wave background generated in these models is provided.

Linear stability of the regular N-gon periodic solutions for the planar N-body problem with quasi-homogeneous potential

Abstract This paper considers the planar N-body problem with a quasi-homogeneous potential given by $$ \begin{align*}W = \sum_{1\leq k&lt;j\leq N} \left[ \frac{ m_k m_j}{\|\boldsymbol{r}_k-\boldsymbol{r}_j\|} +\frac{m_k m_j C_{jk}}{\|\boldsymbol{r}_k-\boldsymbol{r}_j\|^p} \right], \end{align*} $$ where $ m_k&gt;0 $ are the masses and $C_{jk}= C_{kj}$ are nonzero real constants, and the exponent g being $ p&gt; $ 1. Generalizing techniques of the classical N-body problem, we first characterize the periodic solutions that form a regular polygon (relative equilibria) with equal masses ( $m_k= m$ , $k=1, \ldots , N$ ) and equal constants $C_{jk}= C$ , for all $j, k=1, \ldots , N$ (for short, N-gon solutions). Indeed, for $C&gt;0$ we prove that there exists a unique regular N-gon solution for each fixed positive mass m. In contrast, for the case $C &lt;0$ , we demonstrate that there can be a maximum of two distinct regular N-gon solutions for a fixed positive mass m. More precisely, there is a range of values for the mass parameter m for which no solutions of the form of an N-gon exist. Furthermore, we examine the linear stability of these solutions, with a particular focus on the special case $ N=3 $ , which is fully characterized.

Impact of skeletal muscle mass of the trunk and extremities on standing spine parameters before and after surgery for adult spinal deformity with a minimum 2-year follow-up.

The effect of skeletal muscle mass of the trunk and extremities on sagittal imbalance of the spine before and after surgery for adult spinal deformity (ASD) has not been elucidated. The purpose of this study was to examine the correlation between reduced skeletal muscle mass of the trunk and extremities, as well as spinopelvic parameters, preoperatively, postoperatively and at least 2years after surgery for ASD. This retrospective observational study included 140 consecutive patients who had undergone surgery for ASD and were followed-up for at least 2years and whose skeletal muscle mass could be measured preoperatively using whole-body dual-energy X-ray absorptiometry. Correlations between skeletal muscle mass and spinopelvic parameters were assessed preoperatively, postoperatively, and after 2years of follow-up. All spinopelvic parameters were significantly improved postoperatively compared with preoperatively. Between the postoperative period and two years post-surgery, a significant loss of correction was observed in SVA and GT. Trunk muscles mass showed significant negative correlations with preoperative PT, SS, PI-LL, SVA, GT, and TPA, but there was no significant correlation with postoperative parameters. Through univariate and multivariate regression analysis, lower limb skeletal muscle mass showed a significant negative correlation with SVA at two years postoperatively and the loss of corrected SVA (ΔSVA) over two years. This study revealed that lower extremity muscle mass was implicated in the loss of corrected SVA 2years after surgery. This study is clinically meaningful as it suggests that strength training for the lower extremities, performed preoperatively and/or postoperatively, can improve sagittal imbalances of the spine in patients with severe ASD or maintain SVA after corrective surgery.

Exploring Sex-Based Variations in Head Kinematics During Soccer Heading.

While studies indicate that females experience a higher concussion risk and more severe outcomes in soccer heading compared to males, comprehensive data on the underlying factors contributing to these sex-based differences are lacking. This study investigates the sex differences in the head-to-ball impact kinematics among college-aged soccer headers in a laboratory-controlled setting. Forty subjects (20 females, 20 males) performed ten headers, and impact kinematics, including peak angular acceleration and velocity (PAA, PAV) and peak linear acceleration (PLA), were measured using mouthguards. Video recordings verified impacts and impact locations. Participants' head mass was estimated from their weights. The relationship between head mass and kinematic parameters was analyzed using Pearson correlation. The effects of head mass, sex, and impact location on kinematic parameters were assessed using MANOVA with and without head mass as a covariate. Results showed that head mass, larger in males than females, significantly affects PAA and PLA, the greater the head mass, the lower PAA and PLA. However, head mass has no effect on PAV. Females showed significantly higher PAA and PLA components but no significant differences in PAV. Impact location significantly influenced PAV, showing higher magnitudes for frontal impacts compared to top-front impacts, with no significant effects on PAA and PLA. Our results agree with epidemiological evidence that female soccer players face greater concussion risks than males, which can be attributed to their higher header-induced PAA. Future research could consider interventions like changing ball pressure, using protective headgear, and improving heading techniques to reduce high-magnitude accelerations in females.

Insights into dark matter direct detection experiments: decision trees versus deep learning

The detection of Dark Matter (DM) remains a significant challenge in particle physics. This study exploits advanced machine learning models to improve detection capabilities of liquid xenon time projection chamber experiments, utilizing state-of-the-art transformers alongside traditional methods like Multilayer Perceptrons and Convolutional Neural Networks. We evaluate various data representations and find that simplified feature representations, particularly corrected S1 and S2 signals as well as a few shape-related features including the time difference between signals, retain critical information for classification. Our results show that while transformers offer promising performance, simpler models like XGBoost can achieve comparable results with optimal data representations. We also derive exclusion limits in the cross-section versus DM mass parameter space, showing minimal differences between XGBoost and the best performing deep learning models. The comparative analysis of different machine learning approaches provides a valuable reference for future experiments by guiding the choice of models and data representations to maximize detection capabilities.

Adaptive time-varying sliding mode attitude maneuver control for multirotary-joint solar power satellite under constraints

This paper focuses on the problem of attitude maneuver for the Multirotary-joint Solar Power Satellite (MR-SPS) subject to the angular velocity and control torque constraints, mass parameter uncertainties, and external disturbances. The attitude dynamics and kinematics considering the mass parameter uncertainties and external disturbances are first established. Subsequently, a gain-scheduling disturbance observer is designed to eliminate the effect of the mass parameter uncertainties and the external disturbances. A novel nonlinear implicit time-varying sliding surface is constructed to eliminate the reaching phase and limit the angular velocity to a certain range. Based on the time-varying sliding surface, a sliding mode controller is designed in conjunction with the disturbance observer. The time-varying term in the sliding surface can be adjusted according to the control torques to restrict them within an appropriate range to avoid saturation. Lyapunov stability analysis demonstrates that the sliding mode controller can ensure the asymptotic stability of the system. Finally, numerical simulations are performed to illustrate the effectiveness of the proposed control scheme.

Fermion masses, neutrino mixing and Higgs-mediated flavor violation in 3HDM with S3 permutation symmetry

The Yukawa and scalar sectors of a general S3-symmetric three-Higgs doublet model (3HDM) are investigated. The Yukawa interactions are constructed in an S3-invariant way, while the scalar potential contains S3 soft-breaking terms. Global fits to the quark/lepton masses and CKM/PMNS matrices are performed. Excellent fits to all fermion mass and mixing parameters are obtained. Both normal ordering and inverted ordering of neutrino masses are found to be admissible within the framework, with a prediction for the CP-violation phase, δCP ≃ 120°. The fit results in the Yukawa sector are further investigated, together with the scalar sector, imposing constraints from Higgs-mediated neutral meson mixing and neutron electric dipole moment (EDM). We explore the lowest allowed mass of the heavy Higgs bosons, consistent with these constraints, and find it to be about 17 TeV. The corresponding neutron EDM is around 1.7 × 10−27 e-cm, which is within reach of proposed experiments. It is found that the constraints from the K-meson system dominate, while those from the D meson system are marginal.

Numerical Modeling of Engineering-Scale Jointed Coal Mass and Confining Pressure Effect

In coal masses, joints serve as crucial components influencing mechanical responses and failure mechanisms. The joint distribution complicates the acquisition of physical parameters for engineering-scale coal masses, and traditional laboratory or in situ tests often suffer from inaccuracies and high costs. Therefore, examination of the dynamic properties of engineering-scale coal mass is generally performed by numerical simulations. This paper proposes a model construction approach using two-dimension Particle Flow Code (PFC2D) software to study the mechanical properties of engineering-scale jointed coal mass, addressing the limitations of conventional models by integrating scale effects, accuracy, and computational efficiency. Firstly, the distribution characteristics and mechanical parameters of the joints in the coal mass were obtained based on field statistics and laboratory experiments. The parameters of the laboratory-scale model were calibrated by the numerical matching method. The discrete element model for the engineering-scale coal mass was constructed by the step-by-step matching method. The confining pressure effect on the coal mass under a biaxial loading condition was studied, while the strength change, fissure evolution, and failure mechanism under different confining pressures and fissure degrees were investigated. Based on the simulation results, a quantitative relationship was established between the mechanical parameters, fissure degree, and confining pressure under compression conditions. Ultimately, the failure zone ahead of the working face and the distribution of the abutment pressure were assessed using the mechanics parameters of coal masses with diverse joint distributions.

Constraints on the parameters of keV-scale mass annihilating dark matter obtained with SRG/ART-XC observations

Constraints on the parameters of keV-scale mass annihilating dark matter obtained with SRG/ART-XC observations

Detection and characterization of giant planets with Gaia astrometry

ABSTRACT Astrometric observations with Gaia are expected to play a valuable role in future exoplanet surveys. With current data from Gaia’s third data release (DR3), we are sensitive to periods from less than 1 yr to more than 4 yr but, unlike radial velocity (R.V.) are not as restricted by the orbital inclination of a potential planet. The presence and potential properties of a companion affect the primary’s renormalized unit weight error (RUWE) making this a valuable quantity in the search for exoplanets. Using this value and the fitted astrometric tracks from Gaia, we use Bayesian inference to constrain the mass and orbital parameters of companions in known systems. Combining this with R.V. measurements, we show it is possible to independently measure mass and inclination and suggest HD 66141 b is a possible brown dwarf with maximum mass 23.9$^{+7.2}_{-6.4}$ $\mathrm{ M}_{\mathrm{J}}$. We show how this method may be applied to directly imaged planets in the future, using $\beta$-Pictoris c as an example but note that the host star is bright and active, making it difficult to draw clear conclusions. We show how the next Gaia data release, which will include epoch astrometry, will allow us to accurately constrain orbital parameters from astrometric data alone, revolutionizing future searches for exoplanets. Combining predicted observational limits on planet mass with theoretical distributions, we estimate the probability that a star with a given RUWE will host a detectable planet, which will be highly valuable in planning future surveys.