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An efficient SAT encoding for solving The Social Golfer Problem
No full textThe Social Golfer Problem (SGP), a classic NP-complete combinatorial optimization chal- lenge, poses significant scalability issues for automated solvers. To address these limitations, this paper introduces a novel and efficient SAT encoding, the New SAT Encoding (NSE). NSE employs a com- pact three-index variable representation and integrates the New Sequential Counter (NSC) encoding, the proposed technique for Exactly K cardinality constraints, specifically for the SGP’s Group Size constraint. Rigorous experimental evaluation against established encodings, including Triska–Musliu Encoding and Set Constraint Encoding, demonstrates NSE’s superior robustness and performance. Notably, NSE solves a larger number of SGP instances, including the previously intractable 6–3–8 benchmark, outperforming existing SAT-based approaches. While NSE may exhibit a slightly larger clause count in certain configurations, its significantly reduced variable count and solver-friendly CNF structure, enabled by NSC, facilitate enhanced constraint propagation and search efficiency. These results highlight the effectiveness of the NSE encoding and the NSC technique, advancing the state-of- the-art SAT-based solutions for complex combinatorial problems like the Social Golfer Problem
A sustainable economic order quantity model with fuzzy inflation rate, fuzzy promotional effort and fuzzy deterioration rate
No full textThis study represent the exploration of an economic order quantity (EOQ) model where it is perceived that the cost at the starting time of an inventory and the estimated cost of an inventory are not necessarily the same. The reason is defined as a delay in the time interval between cost estimation. and the actual starting time of the inventory. Inflation of money, promotional strategies and debilitation rate of decaying items are included in the model. Instability in political ground or an uncertain situation of a country create more instability in the economic system. Thus, inflation of money is considered. The model represents deterioration rate, inflation of money, and promotional index in fuzzy sense for showing the parametric uncertainty. Therefore, the model is solved by the method of signed distance, triangular fuzzy, and trapezoidal fuzzy for maximization of profit. Carbon emissions due to transportation is calculated for adding the sustainability concept to the model. Optimal order quantity, optimal shortage quantity, optimal selling period and optimal shortage period are found to make the model distinctive. The formulated model is thoroughly explained for both crisp, triangular fuzzy, and trapezoidal fuzzy environment and it is concluded that the trapezoidal fuzzy number is better in its applicability for the decision makers. Because, under the trapezoidal fuzzy environment, the profit value is increased by 10.51% as compared to the crisp environment and 3.89% with respect to the triangular fuzzy environment. One more finding is that, trapezoidal fuzzy number is better with its simple arithmetic operation as well as its easy and intuitive interpretation approach. A practical example from a fertilizer company is considered in the model to add a real touch. Sensitivity analysis is performed and supported by graphical representation. Comparative analysis is derived to show the uniqueness of the model. The model ends with conclusions and direction to possible future studies
Circini: A massive hierarchical triple system with an eclipsing binary
No full textδ Circini is known to be a massive multiple system containing a 3.9 d inner eclipsing binary in a slightly elliptical orbit exhibiting slow apsidal motion and a distant tertiary with a probable period of 1644 d. All three components of the system are O- or B-type stars. We carried out a comprehensive study of the system, based on light curves from TESS and other instruments, a new series of echelle spectra, older spectra from the ESO archive, and several VLTI interferometric observations. Due to the large amount of different types of data covering both orbits in the system, we obtained a more precise value of the long orbital period (1603.24 ± 0.19 d) and fully determined all other orbital parameters. Although both orbits are eccentric, their period ratio is large enough for the system to be dynamically stable. The inner and outer orbits are in the same plane, which means that no Kozai-Lidov mechanism is acting in the system. Assuming solar metallicity in our MESA models, we found ages of (4.4 ± 0.1), (4.7 ± 0.2), and (3.8 ± 1.3) Myr for the primary, the secondary, and the tertiary, respectively. Our evolutionary scenario predicts that the inner eclipsing binary will merge within approximately 1.7 Myr and eventually evolve into a black hole. The distance to the system, estimated from the angular size of the outer orbit is (809.9 ± 1.8) pc, which implies that δ Cir might be located close to the centre of a stellar population ASCC 79, a subgroup of the young Circinus complex. With a total mass of (53.04 ± 0.29) M⊙, δ Cir can contribute a significant fraction of the total mass of the population
Quadruple system HD 135160 in a unique 2+2 configuration
No full textAnalysing a large body of observational data, we found that HD 135160 is a quadruple 2+2 system, composed of a massive ellipsoidal binary (‘heartbeat’ star) with components Aa and Ab in an eccentric 8.234 d orbit and an eclipsing binary (with components Ba and Bb), with a 5.853 d period and partial eclipses that have already been reported from the space photometry secured by the Transiting Exoplanet Survey Satellite (TESS). Our systematic echelle spectroscopy, secured since September 2021, led to the discovery that the optical spectra are dominated by spectral lines of three early-type stars, two moving around each other on a 8.234 d orbit of a high eccentricity, which causes periodic brightenings near the periastron passage, and the third one (component Ba) being the brighter component of the 5.853 d binary. Both pairs are physically bounded and revolve around each other with a period somewhere between 1600 and 2200 days (4.4–6 years). The object exhibits small cyclic light variations of a variable amplitude and characteristic time scale of 0071 (14.14 c d−1), seen throughout the whole orbit. The nature of these tiny changes deserves further investigation. It also seems that the earlier classification of the object as a Be star is unfounded
Confirmation of SRGt 062340.2-265751 as a nova-like cataclysmic variable with a possible magnetic nature
No full textSRGt 062340.2-265751, a cataclysmic variable identified by SRG/eROSITA thanks to its significant X-ray variability, remains poorly characterised despite the multi-wavelength follow-up. We present spectral and timing analyses from the first dedicated X-ray and ultraviolet observations with XMM-Newton, complemented by SRG/eROSITA data from four all-sky surveys (eRASS1-4) and ASAS-SN optical photometry. Our timing analysis reveals a > 8σ significant modulation at 3.6 ± 0.5 hours, likely representing the orbital period. Long-term ASAS-SN monitoring confirms the source as a VY Sculptoris-type nova-like system, while short-timescale X-ray and ultraviolet variability, down to a few minutes, suggests a possible underlying magnetic white dwarf. Two additional significant X-ray modulations at 43 ± 1 min and 36.0 ± 0.7 min tentatively point to the spin period of an intermediate polar. The best-fit XMM-Newton energy spectra reveal a multi-temperature thermal plasma (kT = 0.23, 0.94, and 5.2 keV), while the SRG/eROSITA spectra are consistent with a single-temperature thermal plasma of a few keV. We estimate unabsorbed X-ray luminosities of ≳1032 erg s−1 (0.2–12 keV). Broadband spectral energy distribution modelling, from near-ultraviolet to infrared, indicates a disc-dominated system consistent with a nova-like classification. We discuss these results in the context of the source’s confirmed nova-like classification and its possible magnetic nature, a scenario increasingly supported by discoveries of intermediate polars exhibiting VY Sculptoris-type nova-like features
Warm absorber outflows in radio-loud active galactic nucleus 3C 59
No full textContext. Both jets and ionized outflows in active galactic nuclei (AGNs) are thought to play important roles in affecting the star formation and evolution of host galaxies, but their relationship is still unclear.
Aims. As a pilot study, we performed a detailed spectral analysis of a radio-loud (RL) AGN 3C 59 (z = 0.1096) by systematically considering various factors that may affect the fitting results, thereby establishing a general spectral fitting strategy for subsequent research with a larger sample. AGN 3C 59 is a rare target for simultaneously studying jets and warm absorbers, which are one type of ionized outflow.
Methods. Based on the multiwavelength data from near-infrared (NIR) to hard X-ray bands detected by the Dark Energy Spectroscopic Instrument, Galaxy Evolution Explorer, and XMM-Newton, we used the spe
The PHANGS-MUSE/HST-H
No full textWe present the PHANGS-MUSE/HST-Hα nebulae catalogue, comprising 5177 spatially resolved nebulae across 19 nearby star-forming galaxies (D < 20 Mpc), based on high-resolution Hα imaging from HST, homogenised to a fixed (10 pc) physical resolution and sensitivity. Combined with MUSE integral field spectroscopy, this enables robust classification of 4882 H I
From redshift to real space: Combining linear theory with neural networks
No full textContext. Spectroscopic redshift surveys are key to tracing the large-scale structure (LSS) of the Universe and testing the Λ Cold Dark Matter model. However, redshifts as distance proxies introduce distortions in the 3D galaxy distribution. If uncorrected, these redshift-space distortions (RSDs) lead to systematic errors in LSS analyses and cosmological parameter estimation.
Aims. This study aims to develop and assess a new method that combines linear theory (LT) and a neural network (NN) to mitigate RSDs, with testing done on a suite of dark matter halo catalogs.
Methods. We present a hybrid reconstruction method (LT + NN) combining linear perturbation theory with a NN trained to map halo fields from redshift to real space using a mean squared error (MSE) loss. Training and validation were performed on halo fields from z = 1 snapshots of the Quijote N-body simulations. LT corrects large-scale distortions in the linear regime, while the NN captures smaller-scale and quasi-linear features. Training the NN on LT-corrected fields enables accurate reconstruction across scales.
Results. The LT + NN method reduces the MSE by ∼50% compared to LT and ∼12% compared to NN alone. The reconstructed fields correlate more tightly with the true real-space fields. Compared to LT, the hybrid method shows marked improvements in the halo-halo and halo-void correlation functions, extending to the baryon acoustic oscillation scale. While gains over NN are smaller, they are statistically significant, especially in reducing anisotropies on large and quasi-linear scales, as seen in the quadrupole of the correlation functions.
Conclusions. Combining a physically motivated model with an NN overcomes the limitations of each approach when used separately. This hybrid method offers an effective way to mitigate RSDs with modest training data and computational cost, supporting future applications to more realistic datasets
A search for cold molecular outflows in cosmic-noon galaxies
No full textThe flow of baryons in and out of galaxies is the primary driver for galaxy evolution – inflows bring fresh gas to galaxies that will eventually compress into molecular gas to form stars, and outflows entrain processed gas outside of galaxies. In addition to depleting the gas reservoir of galaxies, outflows also enrich their circumgalactic medium (CGM), which can further impact the next stages of gas accretion, resulting in the presence of molecular gas beyond the stellar component of galaxies out to CGM scales. In this work, we aim to search for cold molecular gas in the CGM of typical main-sequence (MS) star-forming galaxies (SFGs) at cosmic noon (zmed ∼ 1.3), where we expect outflows to be particularly prominent. Using Band-3 carbon monoxide (CO) observations from the Atacama Large Millimeter and submillimeter Array (ALMA), we studied the spatial extent of the cold molecular gas of a sample of 26 SFGs via stacking techniques. We compared this extent to that of the stacked stellar emission of our sample traced by UltraVISTA Ks-band observations. We also searched for broad wings in the stacked spectrum that can be indicative of ongoing outflows. Within the noise level of the observations, we find that the total intrinsic cold molecular gas of our sample spatially extends to scales of RCO ∼ 12 kpc, similarly to the stellar emission (RKs ∼ 13 kpc). We do not find broad wings in the stacked spectrum that could hint at ongoing molecular outflows, but we find a tentative minor excess of CO(2–1) emission at negative velocities that might be indicative of outflows, where the redshifted gas is optically thick. The absence of high-velocity molecular gas suggests that molecular outflows traced by CO(2–1) emission are weak in MS SFGs at cosmic noon. These weak outflows thus fail to expel a significant amount of molecular gas to CGM scales, as indicated by the absence of molecular emission extending beyond the stellar emission region. This lack of CO emission at large radii could also imply that the molecular gas does not survive at such distances
Probing the effect of the protocluster environment on galaxy morphology at
No full textContext. As galaxies evolve in dense cluster and protocluster environments, they interact and quench their star formation. This gradually transforms the dominant galaxy population from star-forming galaxies to quiescent red galaxies. This transformation is identifiable by observing the galaxy colors and can also be seen in the morphological transformation of late-type galaxies into early-type galaxies, which creates the morphology-density relation observed when populations in clusters are compared to field galaxies at a given epoch. However, high-z (z > 2) galaxy morphology studies are hindered by the high angular resolution necessary to characterize the morphology.
Aims. We studied HST WFC3 F160W observations of protoclusters from the MAMMOTH survey (BOSS1244 and BOSS1542) at z ∼ 2.23 with populations of previously identified Hα emitters.
Methods. By measuring the Sérsic index of 151 Hα emitters, we searched for the early morphological transformation of high-z star-forming galaxies in these well-studied large nonvirialized protoclusters, which we think are the precursors of present-day galaxy clusters.
Results. The morphology of the populations of star-forming galaxies in protoclusters does not differ from that of their field counterparts. However, we also identified a population of clumpy potentially merging galaxies, which might increase the population of early-type galaxies within these structures. In BOSS1244, which has two previously identified massive quiescent galaxies including a brightest cluster galaxy (BCG), we additionally found an abundance of early-type galaxies near the BCG and two coeval high-z quasars.
Conclusions. Although the morphology of field and protocluster galaxies are very similar, the population of early-type star-forming galaxies surrounding the spectroscopically confirmed quiescent BCG in BOSS1244, which is not observed in BOSS1542, might indicate differences in the evolutionary state of these two coeval protoclusters. It might be a sign of an early forming cluster core in BOSS1244