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Diagrammatic bosonization, aspects of criticality, and the Hohenberg–Mermin–Wagner theorem in parquet approaches
No full textThe parquet equations present a cornerstone of some of the most important diagrammatic many-body approximations and methods currently on the market for strongly correlated materials: from non-local extensions of the dynamical mean-field theory to the functional renormalization group. The recently introduced single-boson exchange decomposition of the vertex presents an alternative set of equivalent equations in terms of screened interactions, Hedin vertices, and rest functions. This formulation has garnered much attention for several reasons: opening the door to new approximations, for avoiding vertex divergences associated with local moment formation plaguing the traditional parquet decomposition, and for its interpretative advantage in its built-in diagrammatic identification of bosons without resorting to Hubbard–Stratonovich transformations. In this work, we show how the fermionic diagrams of the particle–particle and particle–hole polarizations in the SBE formalism can be mapped to diagrammatics of a bosonic self-energy of two respective bosonic theories with pure bosonic constituents, solidifying the identification of the screened interaction with a bosonic propagator. Resorting to a spin-diagonalized basis for the bosonic fields and neglecting the coupling between singlet and triplet components are shown to recover the trace log theory known from Hubbard–Stratonovich transformations. Armed with this concrete mapping, we revisit a conjecture claiming that universal aspects of the parquet approximation coincide with those of the self-consistent screening approximation for a bosonic O(N) model. We comment on the role of the self-energy and crossing symmetry in enforcing the Hohenberg–Mermin–Wagner theorem in parquet-related approaches
Characterisation of starspot structure and differential rotation of Kepler-411
No full textStarspots and their movements on stellar surfaces enable the mechanisms of stellar magnetic activity to be investigated. Information on the spot distribution and differential rotation provide important constraints for the behaviour of stellar magnetic dynamos.
We analyse the Kepler photometry of Kepler-411, a known exoplanet host, to determine the distribution and properties of star spots on the stellar surface with two independent and complementary methods: modelling the photometric effect of the rotation of spots on the stellar surface and mapping spots by transiting planets.
By constructing a spot model accounting for geometry, differential rotation, and spot evolution, we modelled the spots of the stellar surface giving rise to the observed brightness variations. We also searched for evidence for occultations of starspots in high-cadence photometry.
Our spot models reproduce the observed photometric variations well and we are able to obtain information on the distribution and movement of spots on the stellar surface. We do not obtain evidence for differential rotation -- the rotational profile is consistent with rigid-body rotation with a period of 10.52±0.34 days. We detect three occultations of spots by planet c. The positions of these spots coincide well with the positions of larger spot structures identified by our modelling of the rotational modulation of the light curve
A Bayesian framework for astrometry in a sparse star field and its application to Triton observations
No full textThe DR3 catalog significantly improves ground-based astrometric precision for natural satellites, largely because sufficient reference stars with high-precision positions are typically available within an object's field. These stars enable the determination of a high-order plate model (e.g., a fourth-degree polynomial) that can fully absorb the geometric distortion (GD) in the CCD field. However, accurate calibration is still challenging when a natural satellite moves into a small sparse star field (about 12times12 arcmin2) containing only a dozen or so reference stars. Gaia
This study aims to improve natural satellite astrometry in sparse star fields without requiring the calibration observations that are needed for currently well-established GD solutions. Additionally, our previously published observations of Neptune’s largest satellite, Triton, from 2014 to 2016 show a significant positive systematic offset in right ascension, and the underlying reason will be clarified.
We present a Bayesian framework that models the GD effect using the CCD frames of the science object itself. This approach is self-calibrating and does not require additional calibration observations of dense star fields. The model parameters and their distributions are optimized using the Markov chain Monte Carlo algorithm, and the positional O-C (observed minus computed) values are derived by sampling from these posterior distributions, rather than employing point estimates.
The effectiveness of the proposed approach was evaluated using 985 CCD frames of Triton. The results demonstrate a significant improvement in astrometric precision over the commonly used LS method, and show comparable or even better performance relative to the well-established GD correction method, particularly in the absence of suitable calibration observations. Additionally, we find that the systematic offsets in our previous work on Triton are due to differences in Earth's precession-nutation theory adopted by the Jet Propulsion Laboratory ephemeris for Triton and adopted by the NOVAS library for reference stars
Intracluster globular clusters as tracers of the mass assembly of the Hydra I galaxy cluster
No full textIn galaxy clusters, the hierarchical model of galaxy assembly predicts the formation of stellar substructures and intracluster light (ICL), a diffuse component consisting of stars that are not gravitationally bound to any single galaxy but instead follow the global gravitational potential of the cluster. These features encode the details of the cluster's assembly history. However, observations are challenging due to their faint surface brightness, so independent tracers such as intracluster planetary nebulae and globular clusters (GCs) can provide valuable insight. For this work, we used deep VLT/FORS V- and I-band imaging to study the GC population in the Hydra,I galaxy cluster, a rich environment of galaxies that is located at a distance of 45.7 Mpc. Our photometric sample of GC candidates was constructed from the VI colour-magnitude diagram, where point sources with a similar colour as confirmed GCs were selected. Dividing our GC sample in two colour groups, we show a striking difference between the two populations: while red GCs tend to be clustered around Hydra’s massive galaxies (mainly NGC,3311 and NGC,3309), blue GCs are more extended and spatially coincide with the peak of the cluster’s X-ray emitting gas. The GCs around the central galaxies also have different spatial distributions according to their stellar population properties. Young metal-rich GCs are more extended and may be associated with ram-pressure tails, whereas old metal-poor GCs are more concentrated and could be related to disrupted dwarfs. The red, old, and metal-rich GCs are likely associated with the central massive galaxies. Comparing the GC number density profiles to the surface brightness profile of NGC,3311, we find that the red GCs closely follow the galaxy’s light, while the blue population significantly deviates from it and traces the global gravitational potential of the cluster. This result is also evidenced by the specific frequency of blue GCs, which is ∼5 times larger in the ICL-dominated outskirts when compared to the inner parts of the cluster and to the red population. Finally, we introduce a novel method to constrain the evolution of the galaxy luminosity function of the cluster from GC specific frequencies and colour distributions. This method results in a past Schechter slope of α=-1.81_ -0.16 ^ +0.16 for the faint end compared to α=-1.41_ -0.05 ^ +0.08 in the present day , which is consistent with measurements at high redshift and with cosmological simulations
A homogeneous view of asymptotic giant branch carbon stars as seen by Gaia
No full textContext. Carbon stars on the asymptotic giant branch are major contributors to the dust enrichment of galaxies, with gas mass-loss rate values up to ≈ 10^ M -4 ̊m M_⊙ -1 . They represent the final evolutionary stage of low- and intermediate-mass stars, during which recurrent dredge-up episodes enrich their atmospheres with carbon and trigger the formation of dust. Through their intense winds, they inject large amounts of newly formed carbonaceous dust into the interstellar medium, playing a central role in the chemical evolution of galaxies. Their stellar and dust properties have been studied for decades, with a particular focus on the carbon stars in the Magellanic Clouds (MCs). Aims. Our aim is to homogeneously analyse the DR3 Golden Sample of Carbon Stars through the spectral energy distribution (SED) fitting. Our focus is on sources belonging to the Milky Way (MW) and the MCs. Gaia Methods. Our dataset consists of 14,747 stars with complete multi-band photometry from , 2MASS, and WISE, combined with recent distance and extinction estimates. For a subsample of Mira variables made of 2,494 stars, we also modelled multi-band light curves to obtain accurate mean magnitudes. Stellar and circumstellar properties were derived by fitting the observations with a large grid of synthetic models computed with the DUSTY radiative transfer code, using COMARCS model atmospheres as input. For each target, we determined stellar and dust parameters such as the effective temperature, optical depth, and gas mass-loss rate. Gaia Results. The resulting distributions reveal typical effective temperatures of around 3150 K. Mass-loss rates range from ̊m 10^ -11 to ̊m 10^ -4 ̊m M_⊙ ̊m yr^ -1 . The average dust temperature at the inner bound of the dust shell is about T_d =1000 K. We also observe a correlation between photometric variability amplitude and mass-loss rate. Conclusions. This homogeneous framework provides a unified view of carbon stars across environments spanning a wide range of metallicities, supported by strong statistical coverage. Our results show that some of the physical properties of carbon stars exhibit a dependence on the galactic environment. However, these dependences do not necessarily reflect intrinsic metallicity effects, but are influenced by differences in luminosity distributions and by the selection biases affecting the available samples. The use of and WISE introduces combined selection effects that are significant, limiting the detection of both the most dust-enshrouded objects and the less luminous sources in the Magellanic Clouds. While this limits the completeness of the comparison, the observed trends remain statistically robust within the selected samples
Gaia GraL: The GraL catalogue of gravitationally lensed quasars. X. Matched with Gaia data, redshifts, and time delays
No full textDetermining the Hubble constant tension requires alternative strategies, and multiply imaged quasars, with their intermediate redshifts, can potentially be used in this regard. We provide a currently complete catalogue of spectroscopically confirmed lensed quasars with ESA/ Gaia astrometry and photometry, as well as redshifts and time delays when available. In addition to the improved astrometry, the catalogue increases the number of lensed quasars by a factor of 1.5 (now 364, of which 277 are doubles and 87 are quads or triples) and significantly increases the number of lensing galaxies detected (now 218), which represents a major step forward. Redshifts are provided for 347 quasars and 188 deflectors. A completely new table of time delays, required for estimates of H_0, is presented, with 195 time delays from 73 systems. Gaia absolute astrometry is sub-milliarcsecond and covers the entire sky. Future Gaia data releases will provide long-term photometry, which should provide many more time delays. The catalogues as presented here enable machine-learning techniques to be trained and tested and subsequently applied to the Gaia data releases. Finally, we derive simple but homogeneous models of the 18 quadruply imaged quasars for which images of all four components are presented in Gaia DR3
Improving The Quality of Drinking Water for The Community with Membrane and Ultraviolet Filtration Technology
No full textAccess to safe drinking water remains a critical public health priority. This study evaluates the effectiveness of a combined membrane and ultraviolet (UV) filtration system in improving water quality parameters to meet the Indonesian Ministry of Health standards No.2 2023. Raw water samples (A) and treated water samples (B) were analyzed for TDS, turbidity, color, pH, nitrate, and nitrite using standardized methods (SNI). Results showed substantial reductions in TDS from 172 mg/L to 122 mg/L, turbidity from 136 NTU to 11 NTU, and color from 36.4 PtCo to 12.2 PtCo. pH improved from 5.85 to 6.26, approaching the acceptable range of 6.5-8.5. Nitrate and nitrite concentrations remained well below maximum limits, with slight variations after treatment (nitrate: 0.495 to 0.658 mg/L; nitrite: 0.375 to 0.071 mg/L). The membrane filtration effectively removed suspended solids and reduced turbidity, while UV treatment provided microbial disinfection without altering chemical composition. These findings confirm that integrating membrane and UV technologies can significantly enhance the physicochemical quality of drinking water, making it safer for community consumption. The approach offers a practical, scalable solution for rural and peri-urban areas with limited access to centralized water treatment facilities. Future research should support broader implementation
The Change of
No full textPost-harvest handling is a crucial aspect of the distribution chain for fresh fish, as it ensures the safety and freshness of the commodity for consumers. The Indian mackerel (Rastrelliger sp.) is one of the primary marine protein commodities in East Kalimantan, Indonesia. The objective of the present study was to observe the quality change of indian mackerel fish during supply distribution in Samarinda City. The organoleptic quality, pH, total plate count (TPC), total volatile base (TVB) and water content of the fish were measured at four time points: 4 am in the fish handling facility (TPI Selili), 8 am, 11 am and 2 pm at the traditional market. The data were collected and compared with the National Standardization Body of Indonesia (SNI). The fish quality was found to change significantly at 11 am, with alterations being observed in the quality of the gills, eyes, mucus, aroma and texture of the fish. The TPC also indicated an increase in viable bacteria, exceeding the established standards. The pH level rises substantially due to the enzymes and microbes' activity, which accelerates the spoilage process. Meanwhile, the TVB of all samples remain categorized as safe to consume. The quick and right post-harvest handling is needed to preserve the quality of the fresh fish
Design and optimization of planar undulators for X-ray free-electron lasers: Comparative analyses considerations on magnetic structures
No full textA comparative design and magnetic performance analysis of planar undulator configurations is presented using the 3D magnetostatics simulation code RADIA. Three representative structures are investigated: a pure permanent magnet undulator, a hybrid configuration with Vanadium Permendur poles, and a hybrid configuration with iron poles. The designs are assessed in terms of achievable magnetic field strength, undulator parameter, harmonic content, field uniformity, and overall magnetic field quality. Numerical results obtained from RADIA are systematically compared with theoretical estimates based on established empirical models. Results indicate that the Vanadium Permendur-based hybrid configuration achieves the highest peak magnetic field and improved harmonic purity, thereby satisfying the requirements for high-brilliance synchrotron radiation sources and free-electron laser applications. The iron-based hybrid design provides a cost-effective alternative with competitive performance, while the pure permanent magnet configuration, despite its structural simplicity, shows limited field strength and increased harmonic distortions. These results confirm the reliability of RADIA as a predictive tool for planar undulator design and optimization
Neural networks for 3D characterisation of AGATA crystals
No full textPrecise localisation of gamma-ray interactions is crucial for the performance of the Advanced GAmma Tracking Array (AGATA). The Pulse Shape Analysis (PSA) method used for the position estimation of gamma-ray interactions relies on a simulated signal database. The Pulse Shape Comparison Scanning (PSCS) method was used to scan AGATA crystals in order to produce an experimental database of signals. This paper presents a novel approach using Long Short-Term Memory (LSTM) neural networks to determine the 3D interaction position of gamma rays within AGATA crystals, trained on data from IPHC Strasbourg, allowing for the construction of an experimental database. A custom masked loss function is introduced to enable training with incomplete position information. The database generated by this new method outperforms the existing simulated database, and the experimental database obtained from the conventional PSCS algorithm