Magma Ocean Evolution at Arbitrary Redox State.

Interactions between magma oceans and overlying atmospheres on young rocky planets leads to an evolving feedback of outgassing, greenhouse forcing, and mantle melt fraction. Previous studies have predominantly focused on the solidification of oxidized Earth-similar planets, but the diversity in mean density and irradiation observed in the low-mass exoplanet census motivate exploration of strongly varying geochemical scenarios. We aim to explore how variable redox properties alter the duration of magma ocean solidification, the equilibrium thermodynamic state, melt fraction of the mantle, and atmospheric composition.

A binary system in the S cluster close to the supermassive black hole Sagittarius A.

High-velocity stars and peculiar G objects orbit the central supermassive black hole (SMBH) Sagittarius A* (Sgr A*). Together, the G objects and high-velocity stars constitute the S cluster. In contrast with theoretical predictions, no binary system near Sgr A* has been identified.

High-Statistics Measurement of the Cosmic-Ray Electron Spectrum with H.E.S.S.

Owing to their rapid cooling rate and hence loss-limited propagation distance, cosmic-ray electrons and positrons (CRe) at very high energies probe local cosmic-ray accelerators and provide constraints on exotic production mechanisms such as annihilation of dark matter particles. We present a high-statistics measurement of the spectrum of CRe candidate events from 0.3 to 40 TeV with the High Energy Stereoscopic System, covering 2 orders of magnitude in energy and reaching a proton rejection power of better than 10^{4}.

A machine learning method for predicting telescope cycle time applied to the Cerro Murphy Observatory.

Telescope cycle time estimation is one of the basic issues of observational astronomy. There are not many tools that help to calulate the cycle time for multiple telescopes with multiple instruments. This work presents a new tool for determing the observation time; it was applied at the Cerro Murphy Observatory (OCM) but can be used at any other observatory.

Bridging the gap between GRACE and GRACE Follow-On by combining high-low satellite-to-satellite tracking data and satellite laser ranging.

The satellite missions GRACE and GRACE Follow-On have undoubtedly been the most important sources to observe mass transport on global scales. Within the Combination Service for Time-Variable Gravity Fields (COST-G), gravity field solutions from various processing centers are being combined to improve the signal-to-noise ratio and further increase the spatial resolution. The time series of monthly gravity field solutions suffer from a data gap of about one year between the two missions GRACE and GRACE Follow-On among several smaller data gaps.

Inertial range of magnetorotational turbulence.

Accretion disks around compact stars are formed due to turbulence driven by magnetorotational instability. Despite over 30 years of numerous computational studies on magnetorotational turbulence, the properties of fluctuations in the inertial range-where cross-scale energy transfer dominates over energy injection-have remained elusive, primarily due to insufficient numerical resolution. Here, we report the highest-resolution simulation of magnetorotational turbulence ever conducted.

Automation of finding strong gravitational lenses in the Kilo Degree Survey with U - DenseLens (DenseLens + Segmentation).

In the context of upcoming large-scale surveys like Euclid, the necessity for the automation of strong lens detection is essential. While existing machine learning pipelines heavily rely on the classification probability (P), this study intends to address the importance of integrating additional metrics, such as Information Content (IC) and the number of pixels above the segmentation threshold ([Formula: see text]), to alleviate the false positive rate in unbalanced data-sets. In this work, we introduce a segmentation algorithm (U-Net) as a supplementary step in the established strong gravitational lens identification pipeline (Denselens), which primarily utilizes [Formula: see text] and [Formula: see text] parameters for the detection and ranking.

Molecular dynamics simulations of head-on low-velocity collisions between particles.

The particle contact model is important for powder simulations. Although several contact models have been proposed, their validity has not yet been well established. Therefore, we perform molecular dynamics (MD) simulations to clarify the particle interaction.

Parametric decay instability of circularly polarized Alfvén waves in magnetically dominated plasma.

We investigate parametric decay instability (PDI) of circularly polarized Alfvén wave into daughter acoustic wave and backward Alfvén wave in magnetically dominated plasma, in which the magnetization parameter σ (energy density ratio of background magnetic field to matter) exceeds unity. We analyze relativistic magnetohydrodynamics (MHD), focusing on wave frequencies sufficiently lower than the plasma and cyclotron frequencies. We derive analytical formulas for the dispersion relation and growth rate of the instability as a function of the magnetization σ, wave amplitude η, and plasma temperature θ.

The GRB221009A gamma-ray burst as revealed by the gamma-ray spectrometer onboard the KPLO (Danuri).

The strongest gamma-ray burst (GRB) of the century, GRB20221009A, has been detected by the Korean Pathfinder Lunar Orbiter Gamma-ray Spectrometer (KGRS) instrument onboard the Korean Pathfinder Lunar Orbiter (KPLO). KGRS uses a LaBr detector to measure GRB counts with five energy bins in the energy range from 30 keV to 12 MeV. KGRS detected GRB221009A at a distance of 1.

Science development study for the Atacama Large Aperture Submillimeter Telescope (AtLAST): Solar and stellar observations.

Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progress in (sub-)millimeter observations of the Sun, some important aspects require diagnostic capabilities that are not offered by existing observatories. In particular, simultaneously observations of the radiation continuum across an extended frequency range would facilitate the mapping of different layers and thus ultimately the 3D structure of the solar atmosphere.

Isotropy of Cosmic Rays beyond 10^{20} eV Favors Their Heavy Mass Composition.

We report an estimation of the injected mass composition of ultrahigh energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extragalactic magnetic fields (EGMFs), the results are consistent with a relatively heavy injected composition at E∼10  EeV that becomes lighter up to E∼100  EeV, while the composition at E>100  EeV is very heavy.

Properties of Cosmic Deuterons Measured by the Alpha Magnetic Spectrometer.

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron (D) flux are presented. The measurements are based on 21×10^{6} D nuclei in the rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021.

Association between Ultradian Rhythms of Body Temperature in Small Mammals and Earth's Crust Stress.

Association was assessed between the data harvested by a long-baseline laser interference deformograph and the dynamics of body temperature (BT) in hamsters deprived of natural daily light-darkness changes. The power spectral data revealed the positive correlation between simultaneous time series of hamster BT and the Earth's crust deformation (ECD). The superposed epoch analysis established an association between abrupt upstrokes of hamster BT and ECD increments.

Bound star clusters observed in a lensed galaxy 460 Myr after the Big Bang.

The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref. ).

Time-Delay Cosmography: Measuring the Hubble Constant and Other Cosmological Parameters with Strong Gravitational Lensing.

Multiply lensed images of a same source experience a relative time delay in the arrival of photons due to the path length difference and the different gravitational potentials the photons travel through. This effect can be used to measure absolute distances and the Hubble constant ( ) and is known as time-delay cosmography. The method is independent of the local distance ladder and early-universe physics and provides a precise and competitive measurement of .

Simulations predict intermediate-mass black hole formation in globular clusters.

The formation process of intermediate-mass black holes (IMBHs), defined as those between 100 and 10 solar masses (), is debated. One potential origin is the growth of less-massive black holes merging with stars and compact objects within globular clusters (GCs). However, previous simulations have indicated that this process only produces IMBHs under 500 before gravitational wave recoil ejects them from the GC.

Partial ionization of plasma in solar prominences.

The plasma in cool cores of solar prominences is partially ionized and its ionization degree, in general, depends on the actual kinetic temperature and density of the plasma and the ions considered. However, we demonstrate that under typical prominence conditions, the dominant mechanism contributing to partial ionization is photoionization by radiation diffusing through the plasma. This mechanism strongly depends on the radiation illuminating prominences from the surrounding solar atmosphere.

A case for a binary black hole system revealed via quasi-periodic outflows.

Binaries containing a compact object orbiting a supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely challenging. Here, we report quasi-periodic variability in x-ray absorption, which we interpret as quasi-periodic outflows (QPOuts) from a previously low-luminosity active galactic nucleus after an outburst, likely caused by a stellar tidal disruption. We rule out several models based on observed properties and instead show using general relativistic magnetohydrodynamic simulations that QPOuts, separated by roughly 8.

Interparticle normal force in highly porous granular matter during compression.

We perform a numerical simulation of compression of a highly porous dust aggregate of monodisperse spheres. We find that the average interparticle normal force within the aggregate is inversely proportional to both the filling factor and the average coordination number and we also derive this relation theoretically. Our findings would be applicable for granular matter of arbitrary structures, as long as the constituent particles are monodisperse spheres.

Most of the photons that reionized the Universe came from dwarf galaxies.

The identification of sources driving cosmic reionization, a major phase transition from neutral hydrogen to ionized plasma around 600-800 Myr after the Big Bang, has been a matter of debate. Some models suggest that high ionizing emissivity and escape fractions (f) from quasars support their role in driving cosmic reionization. Others propose that the high f values from bright galaxies generate sufficient ionizing radiation to drive this process.

A high black-hole-to-host mass ratio in a lensed AGN in the early Universe.

Early JWST observations have uncovered a population of red sources that might represent a previously overlooked phase of supermassive black hole growth. One of the most intriguing examples is an extremely red, point-like object that was found to be triply imaged by the strong lensing cluster Abell 2744 (ref. ).