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Two birds with one stone: Simultaneous realization of Lunar Coordinate Time and lunar geoid time with a single orbital clock
No full textThere are three options for defining the lunar reference time. Option O1, using Lunar Coordinate Time, has the advantage of simplicity, while options O2 -- using the lunar geoid (selenoid) time -- and O3 -- using an average alignment with Terrestrial Time -- have the advantage of convenience for users with instruments on the lunar surface and those using Earth navigation satellite signals, respectively. Clock steering must be performed for all three options. O2 and O3 provide new scalings of spatial coordinates and mass parameters in the Solar System.
We propose a `time-aligned orbit' in which the readings of an ideal clock in this orbit are equal to the selenoid time in O2; these readings can be converted to Lunar Coordinate Time in O1 via a known linear transformation.
We show that there exists a time-aligned orbit around the Moon with a semi-major axis of about 1.5 lunar radii that slightly depends on its inclination with respect to the equator of the Moon. We conducted a set of numerical simulations to assess to what extent a clock on these orbits could be used in O2 in a more realistic lunar environment.
The proper time in our simulations de-synchronizes from the selenoid time by up to 190 ns after a year with a frequency offset of 6 which is only 3.75% of the frequency difference in O2 caused by the lunar surface topography. This could be further reduced to 13 ns and 4 if we are able to account for the deviation of the mean orbits in our simulations from the nominal ones. 10^ -16
One can simultaneously realize and use options O1 and O2 by deploying a single clock in the time-aligned orbit. This approach is scalable to other terrestrial planets beyond the Earth--Moon system
First Sardinia Radio Telescope detection of the Sunyaev-Zel’dovich effect at 18.6 GHz
No full textGalaxy clusters imprint a distinctive signature on the cosmic microwave background through the thermal Sunyaev–Zel’dovich (SZ) effect, which enables to study the intracluster plasma distribution and makes them powerful cosmological probes. We present the first Sardinia Radio Telescope (SRT) detection of the SZ effect in the galaxy cluster MACS J1752+4440 at 18.6 GHz, with a resolution of 0.9 _ We detected a decrement in brightness toward the cluster centre, which we attributed to the thermal SZ effect. We modelled the signal using a spherically symmetric β model for the electron density distribution and we employed a Bayesian retrieval to estimate the core radius, central electron density, and β parameter of the cluster. We found values consistent with expectations for a galaxy cluster of the mass of MACS J1752+4440: a core radius of (160 ± 30) kpc, a central electron density of (2.5^ +0.7 -0.5 ⋅ 10^ -3 ) cm -3 (2.6 ± 0.3) ⋅ 10^ -
Formation of magnetic nanoparticle aggregates and their magnetic response in a limited volume
No full textThe effective use of magnetic nanoparticles in biomedicine requires accurately predicting their properties within a cellular environment. A key challenge is the insufficient understanding of how spatial confinement influences their aggregation and collective magnetic response. To address this, we investigate a model of interacting dipole particles confined within a spherical container under a static magnetic field. We employ Monte Carlo simulations to predict the system’s magnetization and characterize the structures that form within it. Our numerical results demonstrate a strong dependence of the magnetic effects on the particle concentration. Cluster analysis quantified the percentage of particles involved in aggregation, revealing a higher proportion in concentrated systems. However, these aggregates form dense, closed structures that respond weakly to the low and moderate magnetic fields. These results provide a theoretical basis for the development of diagnostic and therapeutic applications
Temporal patterns of
No full textThe African oil palm Elaeis guineensis Jacquin has a commercial life span between 20–30 years after which replanting is advised. Although a sound agronomic decision, planted seedlings are at risk of potential attack and damage by adult Oryctes. While it is known that adult population – in infested re‐planted palm plantation – increases with time, specific information on their population trend is limited. Hence the population of the adult Oryctes monoceros pest in 3 years of replanting (YOR) – 2018, 2020, and 2022 – in Ubima Oil Palm Plantation, Rivers State, Nigeria, was monitored, for at least twenty‐seven months, after the planting end month (PEM). Results showed progressive increase in adult population that peaked between 24 to 26 months, then began to decline. The small standard error of the mean (SEM) obtained, showed the sample mean as a precise estimate of the population mean. The one‐way analysis of variance (ANOVA) showed a highly statistical significance across the study months. Similarly, the nested ANOVA showed that variation in O. monoceros population was statistically significant across all tested variables between the three YOR. The study showed that the developmental continuity of O. monoceros is dependent on the trunk and its speed of decay. Furthermore, a second replanting phase will reach peak population faster and will surfer more damage than a first replanting phase. This study provides plantation owners and managers with information on how long the challenge of O. monoceros will likely last, as well as how best to plan replanting activities across multiple years
TOI-333b: A Neptune-desert planet around an F7V star
No full textObservations have shown that planets similar to Neptune are rarely found orbiting Sun-like stars with periods up to ∼4 days. This defines the so-called Neptune desert region. The detection of each individual planet in this region therefore holds a high value by providing detailed insights into the formation and evolution of this population. We report the detection of TOI-333b, a Neptune-desert planet with a mass, radius, and bulk density of 20.1 ± 2.4 M⊕, 4.26 ± 0.11 R⊕, and 1.42 ± 0.21 g cm−3. The planet orbits an F7V star every 3.78 d, whose mass, radius, and effective temperature are of 1.2 ± 0.1 M⊙, 1.10 ± 0.03 R⊙, and 6241−62+73 K, respectively. TOI-333bis likely younger than 1 Gyr, which is supported by the doublet Li line around 6707.856 Å and its comparison to Li abundances in open clusters with well-constrained ages. The planet is expected to host only a 8.5−8.3+10.9% gas-to-core mass ratio for an H/He envelope. On the other hand, models of irradiated ocean worlds predict a 20−10+11% H2O mass fraction with a core fraction of 35−23+20%. We therefore expect that the internal composition of TOI-333bis dominated by a pure rocky composition with almost no H/He envelope, or a rocky world with almost equal mass fraction of water. Finally, TOI-333bis more massive and larger than 77% and 82% of its Neptune-desert counterparts, and its host ranks among the hottest known stars for Neptune-desert planets. This makes this system a unique laboratory for studying the evolution of these planets around hot stars
CGC-induced longitudinal ridge in p-Pb collisions
No full textWithin the Color Glass Condensate (CGC) effective field theory, we investigate the long-range rapidity correlations in proton-lead (p-Pb) collisions at TeV. A distinctive correlation rebound is observed, where the correlation bounces after reaching a minimum at large rapidity gaps (). The rebound means a strong correlation appears at large rapidity gap. Studying the rebound structures can thus illuminate the formation of the ridge. We find that the rebound is most obvious when the transverse momenta of two measured particles are around 2 , and it moves to larger rapidity gaps at higher collision energies. Beyond that, the rapidity correlations in p-Pb collisions show asymmetry when the transverse momenta of two particles differ. The asymmetry, a unique signature of the asymmetric collisions, vanishes when the transverse momenta of two particles coincide. These findings provide direct insight into gluon saturation and quantum evolution
Primordial black holes within Higgs hybrid metric-Palatini approach
No full textIn this paper, we investigate the production of primordial black holes (PBHs) during the radiation-dominated era. The collapse of significant density perturbations originating from large primordial scalar fluctuations generated during inflation can lead to the formation of primordial black holes. In our study, we adopt the Higgs hybrid metric-Palatini model as our framework, in which the inflaton field and the Palatini curvature are non-minimally coupled. To achieve our objective, we analyze the behavior of the primordial curvature power spectrum, which exhibits a large enhancement at small scales corresponding to large wavenumbers k. Furthermore, we examine the probability of PBHs formation by studying the mass variance, , and the mass fraction of the total energy density collapsing into PBHs, . The evolution of both functions is consistent with current observational constraints. Finally, we investigate the abundance of primordial black holes as a dark matter candidate. We found that they can account for the totality or a fraction of the current dark matter content, depending primarily on the values of the coupling constant and the e-folds number
Multi-messenger standard-siren cosmology for third-generation gravitational-wave detectors: forecasts considering observations of gamma-ray bursts and kilonovae
No full textIn the third-generation (3G) gravitational-wave (GW) detector era, GW multi-messenger observations for binary neutron star merger events can exert significant effects on exploring the cosmic expansion history. Extending a previous work, we explore the potential of 3G GW standard siren observations in cosmological parameter estimation by considering their associated electromagnetic (EM) counterparts, including -ray burst (GRB) coincidence observations by the Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor and GW-triggered target-of-opportunity observations of kilonovae by different optical survey projects. During an assumed 10-year observation, we predict that the number of detectable GW-kilonova events is with redshifts below under the GW detector network and Large Synoptic Survey Telescope in the i band, which is more than three times that of GW-GRB detections. For the cosmological analysis, we find that with the inclusion of GW-kilonova detections, the constraints on cosmological parameters from GW-EM detections are significantly improved compared to those from GW-GRB detections. In particular, GW-EM detections can tightly constrain the Hubble constant with precision ranging from to . Moreover, GW multi-messenger observations can effectively break the cosmological parameter degeneracies generated by the typical EM observations, CMB+BAO+SN (CBS). The combination of CBS and GW-EM can tightly constrain the equation-of-state parameters of dark energy w in the wCDM model and in the CDM model with precision of and , respectively, meeting the standard of precision cosmology. In conclusion, GW multi-messenger observations could play a crucial role in helping solve the Hubble tension and probing the fundamental nature of dark energy
Optical appearance of Schwarzschild black holes with optically thin and thick accretion disks at various inclination angles
No full textIn this paper, we systematically investigate the optical appearance of a Schwarzschild black hole illuminated by three geometrically thin accretion disk models under varying observational inclination angles. Based on the geometric relationship between the black hole and observer, we first divide the accretion disk into co-side and counter-side semi-disks. We then analyze light ray trajectories, and calculate the total number of orbits and transfer functions for both semi-disks. The results reveal distinct inclination-dependence of lensed regions on different semi-disks: as inclination increases, the lensed region contracts for the counter-side semi-disk while expanding for the co-side one. Furthermore, through explicit specification of the emission profiles of the three models, we present optical images for both optically thin and thick disk scenarios at different inclinations. The results demonstrate that: (i) the bright rings in all three models become progressively compressed and deviate from circularity as inclination increases; (ii) for thick disks, partial rings are obscured and the overall intensity is lower than thin disks. These results may advance our understanding of general black hole imaging processes and provide a new approach to test gravitational theories through optical morphology studies
