Sazuna/UAT_keywords huggingface dataset:
Correcting for Interloper Contamination in the Power Spectrum with Neural Networks. Modern slitless spectroscopic surveys such as Euclid and Roman collect vast numbers of galaxy spectra, but their low signal-to-noise ratios often lead to incorrect redshift assignments when relying on a single emission line. This misidentification, commonly caused by noise spikes or nontarget emission-line contamination, results in redshift interlopers. We present a machine learning method to mitigate interloper effects at the level of cosmological summary statistics, focusing on the power spectrum monopole as a test case. Using halo catalogs from the QUIJOTE simulations as galaxy proxies, we simulate interlopers by displacing a fraction of halos by redshift offsets between target and interloper populations. This yields contaminated catalogs spanning a wide cosmological parameter space. We train a neural network on the power spectrum monopole, alone or combined with the bispectrum monopole, from contaminated mocks to estimate the interloper fraction and reconstruct the cleaned power spectrum. We assess performance in two scenarios: one with fixed cosmology and one where cosmological parameters vary. In the fixed case, the method recovers the interloper fraction and corrects the power spectrum to 1% accuracy. When cosmology varies, performance degrades, but including bispectrum information improves results, reducing interloper fraction errors and correcting with 2% accuracy. We also analyze how the size of the training set and the correlation between target and interloper populations affect performance. When these samples are uncorrelated, bispectrum information is more beneficial; when strongly correlated, tighter cosmological priors offer greater improvements. Our results demonstrate the potential of machine learning to enhance cosmological inference in contaminated spectroscopic data sets.

Keywords: Redshift surveys
Synergistic Radiative Transfer Modeling of Mg II and Lyα Emission in Multiphase, Clumpy Galactic Environments: Application to Low-redshift Lyman Continuum Leakers. We conducted systematic radiative transfer (RT) modeling of the Mg II doublet line profiles for 33 low-redshift Lyman continuum (LyC) leakers, and Lyα modeling for six of these galaxies, using a multiphase, clumpy circumgalactic medium (CGM) model. Our RT models successfully reproduced the Mg II emission line profiles for all galaxies, revealing a necessary condition for strong LyC leakage: high maximum clump outflow velocity ( vMgII,max≳390kms−1 ) and low total Mg II column density (NMgII, tot ≲ 1014.3 cm−2). These two parameters have the strongest influence on the emergent Mg II profile. For the six galaxies with archival HST data, our Lyα modeling shows that their spectral properties do not consistently match conventional LyC leakage criteria. A direct comparison of the best-fit Mg II and Lyα model parameters reveals no clear correlations in clump outflow velocities, column densities, or volume filling factors, suggesting that H I and Mg II may not be kinematically or spatially coherent. The inferred LyC escape fraction from Lyα modeling is primarily governed by the number of optically thick H I clumps per sightline (fcl). Intriguingly, two galaxies with low observed LyC leakage exhibited the highest RT-inferred LyC escape fractions, due to having the lowest fcl values, driven by strong Lyα blue peaks. Future spatially resolved observations will be crucial for resolving this puzzle. Our results support a "picket fence" CGM geometry over a "density-bounded" scenario, where high Mg II outflow velocities and low Mg II column densities trace low-density H I channels that facilitate LyC escape.

Keywords: Galactic winds, Ultraviolet spectroscopy, Emission line galaxies, Radiative transfer, Interstellar medium, Circumgalactic medium, Reionization
Some Interesting Observations of Cosmic Ray Variations during the Extreme Solar Storm on 2024 May 10–11. Multiple interplanetary coronal mass ejections (ICMEs) erupted from AR 13664 during 2024 May 8–13. On 2024 May 10, after the arrival of the ICME shock at 17:04 UT, a Forbush Decrease (FD) was seen in various Neutron Monitor (NM) stations located worldwide. This paper presents a comprehensive analysis of neutron data from 28 NM stations and gamma-ray data obtained from the NaI(Tl) detector at Maitri, Antarctica. The present paper reports for the first time about an ICME shock-sheath related enhancement of ∼3%–5% magnitude in the neutron flux at stations with geomagnetic rigidity between 4 and 7 GV, located at higher altitudes (≥1000 m). For these stations, the high-rigidity ends of the asymptotic trajectories are confined to the midnight to the postmidnight region. It appears that the increase may be associated with magnetospheric particle precipitation triggered by the passage of the ICME shock-sheath. The variation of FD amplitude with rigidity shows a decreasing trend in general, with a minimum amplitude at 5–7 GV, which we attribute to the location of field-aligned currents (FACs). The FD amplitude is found to have the effects of storm-time westward ring current, FACs, and magnetospheric dynamics, in addition to the ICME parameters. During the recovery phase of FD, enhancement is observed between 01:50 and 03:00 UT on 2024 May 11, which coincided with Ground Level Enhancement (GLE#74). The GLE#74 was coeval with the strong SYM-H index and the sudden recovery of the FD due to reduced interplanetary magnetic field, which might be responsible for the observed enhancement at high rigidity stations.

Keywords: Secondary cosmic rays, Shocks, Galactic cosmic rays, Solar coronal mass ejections, Solar storm
On the Ordering of Exoplanet Systems. We present a comprehensive analysis of planetary radius ordering within multiplanet systems, namely their ordinal position with respect to their size in a given system, utilizing data from the NASA Exoplanet Archive. In addition, we consider not only the ordinal positions but also the specific period ratios and radius ratios of planetary pairs in multiplanet systems. We explore various dependencies on stellar host type and metallicity, as well as planetary type, and explore the differences between planetary systems with different planet multiplicities and different planetary pairs in the same system. Focusing on Kepler systems with two to four planets, we account for observational biases and uncover a robust trend of smaller inner planets. This trend is particularly pronounced in inner pairs of three-planet systems and exhibits variations in stellar metallicity and planet multiplicity. Notably, we find that the distribution of inner-to-outer planet radius ratios depends on the systems' metallicities, suggesting a link between the initial conditions and the resulting system architecture. Interestingly, planet pairs in resonance do not exhibit significantly different size ratios compared to nonresonant pairs, challenging current theoretical expectations, again, possibly suggesting that initially resonant systems could have been later destabilized. Our findings align with planet formation and migration models where larger planets form farther out and migrate inward. Importantly, we emphasize the significance of planet ordering as a novel and crucial observable for constraining planet formation and evolution models. The observed patterns offer unique insights into the complex interplay of formation, migration, and dynamical interactions shaping planetary systems.

Keywords: Exoplanet dynamics, Exoplanet migration, Planetary system evolution, Planetary-disk interactions, Exoplanet systems, Exoplanet astronomy, Planetary system formation, Planet hosting stars, Planetary migration, Exoplanet formation, Planetary dynamics
Quantifying the Active Galactic Nucleus Fraction in Cosmic Voids via Mid-infrared Variability. Observations and theoretical simulations suggest that the large-scale environment plays a significant role in how galaxies form and evolve and, in particular, whether and when galaxies host an actively accreting supermassive black hole in their center (i.e., an active galactic nucleus; AGN). One signature of AGN activity is luminosity variability, which appears in the mid-IR when circumnuclear dust reprocesses UV and optical photons from the AGN accretion disk. We present here a suite of constraints on the fraction of AGN activity in the most underdense regions of the Universe (cosmic voids) relative to the rest of the Universe (cosmic walls) by using ∼12 yr of combined multiepoch data from AllWISE and NEOWISE to quantify mid-IR variability. We find clear evidence for a larger mid-IR variability−AGN fraction among high- and moderate-luminosity void galaxies compared to their wall counterparts. We also show that mid-IR variability identifies a rather large and unique population of AGNs, the majority of which have eluded detection using more traditional AGN selection methods such as single-epoch mid-IR color selection. The fraction of these newly recovered AGNs is larger among galaxies in voids, suggesting once again more prolific AGN activity in the most underdense large-scale structures of the Universe.

Keywords: Active galactic nuclei, Infrared galaxies, Voids
HerS-3: An Exceptional Einstein Cross Reveals a Massive Dark Matter Halo. We present a study of HerS-3, a dusty star-forming galaxy at zspec = 3.0607, which is gravitationally amplified into an Einstein cross with a fifth image of the background galaxy seen at the center of the cross. Detailed 1 mm spectroscopy and imaging with NOEMA and the Atacama Large Millimeter/submillimeter Array resolve the individual images and show that each of the five images display a series of molecular lines that have similar central velocities, unambiguously confirming that they have identical redshifts. The Hubble Space Telescope F110W image reveals a foreground lensing group of four galaxies with a photometric redshift zphot ∼ 1.0. Lens models that only include the four visible galaxies are unable to reproduce the properties of HerS-3. By adding a fifth massive component, lying southeast of the brightest galaxy of the group, the source reconstruction is able to match the peak emission, shape, and orientation for each of the five images. The fact that no galaxy is detected near that position indicates the presence of a massive dark matter halo in the lensing galaxy group. In the source plane, HerS-3 appears as an infrared luminous starburst galaxy seen nearly edge on. The serendipitous discovery of this exceptional Einstein cross offers a potential laboratory for exploring at small spatial scales a nuclear starburst at the peak of cosmic evolution and studying the properties of a massive dark matter halo associated with the lensing galaxy group.

Keywords: Strong gravitational lensing
Doppler-shifted Signatures in the Chromospheric Line Profiles of II Pegasi. Stellar flares are frequently accompanied by prominence eruptions, coronal mass ejections (CMEs), and other forms of plasma motion. Based on the long-term high-resolution spectroscopic monitoring data set of the RS CVn-type star II Pegasi (II Peg), we search for stellar prominence eruptions and potential CMEs by investigating asymmetric signatures in the Hα and Hβ line profiles during the flare events. We observed seven optical flares with asymmetric spectral profiles, releasing low limit energies of 1033–1034 erg in the Hα line. Five of these flares were associated with six potential CMEs, identified through the Doppler-shifted emission signatures in the chromospheric line profiles, particularly the Hα line. The mass estimates for the CME candidates range from 1019 to 1020 g, while the kinetic energies are calculated to be around 1033–1034 erg. The most massive CME candidate was simultaneously recorded in the Hα, Hβ, and He I D3 lines. For II Peg, the possible flare–CME association rate is about 30%. There were also some redshifted excess absorption signatures in the Hα line profiles. These signatures could not only be observed in the flaring spectra but also in the spectra without flare, which could be interpreted as features resulting from flare-driven coronal rain and quiescent rain, respectively.

Keywords: Stellar chromospheres, Stellar activity, RS Canum Venaticorum variable stars, Optical flares, Stellar coronal mass ejections, Spectroscopy, Stellar coronae
Coronal Cells in Coronal Holes: Systematic Analysis and Implications for Coronal Evolution. Using advanced processing techniques, we analyze high-cadence, high-resolution extreme-ultraviolet images and show that, throughout the solar cycle, midlatitude coronal holes (CHs) are made up of ubiquitous and space-filling funnel-shaped structures (or cells) anchored to unipolar magnetic flux concentrations in network lanes. We demonstrate that the coronal cells, previously documented in the magnetically closed regions, and coronal plumes, inside CHs, are a particular manifestation of ubiquitous cells. The cell properties depend on the magnetic field intensity at their footpoint and connectivity in the corona, either closing in opposite-polarity regions (CF-cells) or extending to form open field (OF-cells). The OF-cells reach size scales on the order of supergranules and are characterized by dark lanes delimiting ray-like features both showing, at different levels, persistent jetlike ejections. The cells' lifetime mirrors that of magnetic flux concentrations revealed by magnetograms, slowly emerging and then disappearing in a matter of a few hours to a few days in a one-to-one correspondence. When a cell forms along the CH boundary, it can alter the CH boundary by shrinking or expanding the CH by an approximately supergranular cell unit. Therefore, coronal cells can contribute to the dynamics of the CH boundary. We contextualize these observations in a "coronal cell" theory potentially able to provide an explanation for fine-scale coronal structures and jetting activity in polar CHs.

Keywords: Astronomical techniques, Quiet sun, Solar wind, Solar corona
Revisiting Galaxy Cluster Scaling Relations through Dark Matter–Gas Coherence: Scatter Dependence on Dynamical State. Galaxy clusters, the most massive, dark-matter-dominated, and most recently assembled structures in the Universe, are key tools for probing cosmology. However, uncertainties in scaling relations that connect cluster mass to observables like X-ray luminosity and temperature remain a significant challenge. In this paper, we present the results of an extensive investigation of 329 simulated clusters from IllustrisTNG300 cosmological simulations. Our analysis involves cross-correlating dark matter and the hot X-ray-emitting gas, considering both the 3D and 2D projected distributions to account for projection effects. We demonstrate that this approach is highly effective in evaluating the dynamical state of these systems and validating the often-utilized assumption of hydrostatic equilibrium, which is key for inferring cluster masses and constructing scaling relations. Our study revisits both the X-ray luminosity–mass and X-ray temperature–mass scaling relations, and demonstrates how the scatter in these relations correlates with the clusters' dynamical state. We demonstrate that matter–gas coherence enables the identification of an optimal set of relaxed clusters, reducing scatter in scaling relations by up to 40%. This innovative approach, which integrates higher-dimensional insights into scaling relations, might offer a new path to further reduce uncertainties in determining cosmological parameters from galaxy clusters.

Keywords: Extragalactic astronomy
The Timing Evolution of the Magnetar Swift J1818.0─1607 during a Period of Reduced Activity. We report results from an observational campaign of the radio-loud magnetar Swift J1818.0−1607 using the Green Bank Telescope at 2.0 GHz that began in 2021 November, during a period of reduced activity approximately 20 months after its 2020 March outburst. Over the ∼60 day duration reported here, the integrated pulse profile remained consistently stable, exhibiting a single, narrow peak with a small precursor component and no evidence of a postcursor one. This pulse profile is in sharp contrast to the double-peaked morphology observed during an observing campaign ∼120 days preceding ours. Along with this change in the integrated pulse profile shape, we also measured a slower spin-down rate ( ν̇ ) compared to the end of that preceding campaign. Together, these differences suggest that a mode-switching event likely occurred between the end of that campaign and the start of ours. Finally, we derived a phase-connected timing solution from our data, from which we inferred a characteristic age of τc ∼ 2500 yr—about 2.5 times older than the most recent published estimate—and a surface dipole magnetic field strength of Bfield ∼ 1 × 1014 G, nearly 3 times weaker. These updated estimates reflect the short-term variations in the magnetar's spin-down rate, from which both its age and magnetic field strength are inferred, rather than intrinsic changes in the magnetar itself.

Keywords: Neutron stars, Rotation powered pulsars, Non-thermal radiation sources, Magnetars, Radio pulsars
Supermassive Black Hole Growth in Hierarchically Merging Nuclear Star Clusters. Supermassive black holes are prevalent at the centers of massive galaxies, and their masses scale with galaxy properties, increasing evidence suggesting that these trends continue to low stellar masses. Seeds are needed for supermassive black holes, especially at the highest redshifts explored by the James Webb Space Telescope. We study the hierarchical merging of galaxies via cosmological merger trees and argue that the seeds of supermassive black holes formed in nuclear star clusters via stellar black hole mergers at early epochs. Observable tracers include intermediate-mass black holes, nuclear star clusters, and early gas accretion in host dwarf galaxies, along with a potentially detectable stochastic gravitational-wave background, ejection of intermediate and supermassive black holes, and consequences of a significant population of early tidal disruption events and extreme mass ratio inspirals.

Keywords: Supermassive black holes
ALMA Observations of Molecular Complexity in the Large Magellanic Cloud: Probing the Star-forming Region N 160. Hot cores are small (≲0.1 pc), dense (≥106 cm−3), and hot (&gt;100 K) regions around massive protostars and are one of the main production sites of complex organic molecules (COMs, ≥6 atoms, including carbon). The Large Magellanic Cloud (LMC) is an ideal place to study hot core and COM formation in an environment that is different from our Galaxy, though prior to this study there have only been nine detections of extragalactic hot cores (seven in the LMC and two in the Small Magellanic Cloud, SMC). Here, we report 1.2 mm continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array in the star-forming region N 160, which we named N 160A─mm. We identify six 1.2 mm continuum sources, four of which are associated with methanol (CH3OH) emission. Another COM, methyl cyanide (CH3CN) is associated with the brightest source, N 160A─mm A, the most chemically rich source in the field. Using the XCLASS software, we perform spectral modeling to estimate rotational temperatures and total column densities of detected molecular species for four sources. Based on the temperature exceeding 100 K, its small size, and high H2 number density, we identify N 160A─mm A as a hot core. We compare the molecular abundances of this newly detected hot core with those previously detected in the LMC and SMC, as well as with a sample of Galactic hot cores, and discuss the complex nature of N 160A─mm A.

Keywords: Star forming regions, Chemical abundances, Astrochemistry, Star formation, Protostars, Magellanic Clouds
Time-dependent MHD Simulation of the Lunar Limb Compression Caused by the Core-induced Magnetic Field. Using a time-dependent magnetohydrodynamic simulation, we demonstrated the lunar limb compression caused by the core-induced magnetic field. When a sudden change occurs in the upstream interplanetary magnetic field (IMF), an induced response is generated within the Moon's conductive core. When the direction of the IMF jump is the same as the IMF direction after the jump, a diamagnetic current is driven inside the core, strengthening the magnetic field beneath the lunar surface but outside the core. In most dayside regions, this induced subsurface magnetic pressure is suppressed by the strong solar wind dynamic pressure. However, in regions near the terminator, where the solar wind dynamic pressure is lower, this induced subsurface magnetic pressure can compress the solar wind above the lunar surface, forming limb compression structures around the Moon. This work not only clarifies a new physical mechanism for the source of the lunar limb compression (driven by the core-induced magnetic field rather than the crustal magnetic field) but also ascertains the starting position of the limb compression, as well as its temporal variation during the IMF jump. These results can greatly improve our understanding of the Moon's electromagnetic environment and have potential applications to constrain the conductive state of lunar core.

Keywords: Magnetohydrodynamics, The Moon, Solar-planetary interactions
Biermann Battery Magnetic Flux Generation in the Deep Solar Interior. Time-series analyses of helioseismic data and solar neutrino data have indicated the potential existence of a second tachocline at the core–radiative zone interface, which may in turn require consideration of an additional source of magnetic flux generation in the deep solar interior (r/R⊙ ≲ 0.5). This work considers the generation of a Biermann battery magnetic flux in the deep solar interior and the potential transport of that magnetic flux outward by diffusion. At low latitudes, we expect this additional flux to interact with the flux generated at the base of the convective zone to result in the solar magnetic field observed near the ecliptic. At high latitudes, the diffused flux may manifest as scattered regions of intense polar fields that could be measured by appropriate instruments on spacecraft far off the ecliptic.

Keywords: Solar physics, Solar rotation, Solar magnetic fields, Solar interior
Thermonuclear Heating of Accreting Neutron Stars. We describe a new method to incorporate thermonuclear heating in the envelope of accreting neutron stars into long-term simulations of their thermal evolution. We obtain boundary conditions for the heat exchange between the envelope and the crust based on stationary models, which include nuclear burning, and validate these values by comparing them to the results of the time-dependent code MESA. These simple boundary conditions allow us to explore a large parameter space. We quantify the amount of heat flowing from the envelope into the crust, or vice versa, depending on the mass accretion rate, outburst duration, and duty cycle, and especially crust/core physical parameters such as impurities, crustal heating, and neutrino cooling rate.

Keywords: Neutron stars, Nuclear astrophysics, Stellar accretion