The Korea Astronomy and Space Science Institute (KASI) is the national research institute in astronomy and space science of South Korea funded by the South Korean Government. Its headquarters are located in Daejeon, in the Daedeok Science Town. Research at KASI covers main areas of modern astronomy, including Optical Astronomy, Radio Astronomy, Space Science, and Theoretical Astronomy..
Abstract Observing the polarization of the lunar regolith is essential for obtaining detailed information about the composition and characteristics of lunar soil. Observations conducted via lunar orbiters facilitate polarization measurements over wide areas; however, achieving very high‐resolution imaging requires either a large optical system or a narrow field of view, both of which complicate observations under varying incident angle conditions. Furthermore, when the lunar surface is imaged at high resolution, the emission angle can vary significantly due to the slope and orientation of local terrain features such as craters and hills. This variability is particularly pronounced in young craters, where steep slopes near the rim result in emission angles that are nearly horizontal. In addition, unlike ground‐based observations, orbital systems can observe the same region at various times and from different angles, resulting in significant variation in the off‐plane angle between the satellite, the target area, and the Sun. Consequently, the Sun, target, and detector may not align linearly on the lunar surface. In this study, we measured the degree of polarization of the JSC‐1A lunar soil simulant at various incident, reflection, and off‐plane angles to examine how the polarizer angle changes under different conditions. The results show that even at the same phase angle, the degree of polarization varies significantly with incident and off‐plane angles, indicating that these geometric factors must be considered for accurate interpretation of polarization measurements. These measurements are expected to aid in identifying critical factors for accurately interpreting polarization data obtained from the lunar surface.
While the simplest inflationary models predict a power-law form of the primordial power spectrum (PPS), various UV complete scenarios predict features on top of the standard power law that leave characteristic imprints in the late-time distribution of matter, encoded in the galaxy power spectrum. In this work, we assess the validity of the Effective Field Theory of Large Scale Structure (EFTofLSS) and the IR-resummation scheme of PyBird in the context of primordial (oscillatory) features. We find an excellent agreement at the level of the matter power spectrum between N-body simulations and the one-loop EFT predictions, for models commonly studied in the literature. We then apply the EFTofLSS to the galaxy power spectrum measurements from BOSS LRG and eBOSS QSO to constrain specific global and local features in the PPS. We demonstrate that while such features can improve the fit to cosmic microwave background (CMB) data, they may result in a poorer fit to clustering measurements at low redshift. The resulting constraints on the amplitude of the primordial oscillations are competitive with those obtained from CMB data, despite the well-known damping of oscillations due to non-linear structure formation processes. For the first time in this context, we jointly analyze the galaxy power spectrum (monopole and quadrupole) in combination with Planck CMB data to derive strong constraints on the amplitude of primordial features. This work highlights the EFTofLSS as a powerful tool for testing early universe scenarios on scales that complement CMB observations.
Aims. We introduce NEWCLUSTER, a novel high-resolution cluster simulation designed to serve as the massive halo counterpart of the modern cosmological galaxy evolution framework. Methods. The zoom-in simulation targets a volume of 4.1σ overdensity region, which is expected to evolve into a galaxy cluster with a virial mass of 5 × 1014 M⊙, comparable to that of the Virgo Cluster. The zoom-in volume extends out to 3.5 virial radii from the central halo. The novelties of NEWCLUSTER are exemplified by its resolution. Its stellar mass resolution of 2 × 104 M⊙ is effective for tracing the early assembly of massive galaxies as well as the formation of dwarf galaxies. The spatial resolution of 68 parsecs in the best-resolved regions in the adaptive-mesh-refinement approach is a powerful tool for studying the detailed kinematic structure of galaxies. The time interval between snapshots is also exceptionally short (i.e., 15 Myr). This is ideal for monitoring changes in the physical properties of galaxies, particularly during their orbital motion within a larger halo. The simulation includes up-to-date feedback schemes for supernovae (SNe) and active galactic nuclei (AGNs). The chemical evolution is calculated for ten elements, along with dust calculation that includes the formation, size change, and destruction. To overcome the limitations of the Eulerian approach used for gas dynamics in this study, we employed Monte Carlo-based tracer particles in NEWCLUSTER, enabling a wide range of scientific investigations. Results. The simulation has passed z = 0.8, covering well over half of its cosmic history. We released the early data with the expectation they will facilitate studies of the early evolution of galaxies and overdensities.
Crystalline silicates form at high temperatures (>900 K) (refs. 1,2). Their presence in comets3-6 suggests that high-temperature dust processing occurred in the early Solar System and was subsequently transported outwards to comet-forming regions. However, direct evidence for this crystallization and redistribution in Sun-like protostars has remained unknown. By comparing James Webb Space Telescope mid-infrared spectra of the periodically bursting protostar EC 53 (ref. 7), we detect crystalline silicate (forsterite and enstatite) emission features that appear only during the burst. The emergence of these features indicates active crystal formation by thermal annealing in the hot inner disk during the accretion burst. We also detect a nested outflow-a collimated atomic jet enclosed by slower molecular outflows, consistent with magnetohydrodynamic wind models8. This configuration provides a mechanism for the outward transport of freshly crystallized silicates9. To our knowledge, our results provide the first direct observational evidence of in situ silicate crystallization during episodic accretion bursts in a very young star still embedded in its dense envelope. Although we do not directly detect grains transported to the outer disk, the observed trends are consistent with outward redistribution, indicating that both dust processing and transport occur during the earliest and most dynamic stages of star formation.
To assess the significance and scale dependence of anomalous large scale modes in the CatWISE quasar data, we generate smoothed number density fields on the sphere comparing these summary statistics to those obtained from random isotropic realisations of the data, we determine the statistical significance of large scale modes as a function of smoothing scale. We perform our analysis using five different versions of the data - the original quasar map, the maps after separately subtracting the ecliptic bias and the CMB dipole, the map obtained after subtracting both, and the map after subtracting the ecliptic bias and anomalous dipole inferred in [1]. We find that the ecliptic-corrected, CMB dipole-removed map exhibits large scale modes that are in tension with random realisations of the data (p-values p less than or similar to 10-4), over a wide range of smoothing scales pi /8 <= delta <=pi /2. The most prominent feature in the data is an under-density in the southern galactic plane at (b, & ell;) = (-31 degrees, 78 degrees), which reaches its highest statistical significance when smoothed on scales behavior in the data is primarily driven by the under-density in the southern sky. The ecliptic corrected, anomalous dipole subtracted map reduces the significance of any residual anisotropic features, but an under-density in the south sky persists with p-value p = 0.0018.
