Sazuna/UAT_keywords huggingface dataset:
More Likely Than You Think: Inclination-driving Secular Resonances Are Common in Known Exoplanet Systems. Multiplanet systems face significant challenges to detection. For example, farther-orbiting planets have a reduced signal-to-noise ratio in radial velocity detection methods, and small mutual inclinations between planets can prevent them from all transiting. One mechanism for exciting mutual inclination between planets is secular resonance, where the nodal precession frequencies of the planets align so as to greatly increase the efficiency of the angular momentum transport between planets. These resonances can significantly misalign planets from one another, hindering detection, and typically can only occur when there are three or more planets in the system. Naively, systems can only be in resonance for particular combinations of planet semimajor axes and masses; however, effects that alter the nodal precession frequencies of the planets, such as the decay of stellar oblateness, can significantly expand the region of parameter space where resonances occur. In this work, we explore known three-planet systems, determine whether they are in (or were in) secular resonance due to evolving stellar oblateness, and demonstrate the implications of resonance on their detectability and stability. We show that about 20% of a sample of three-planet transiting systems seem to undergo these resonances early in their lives.

Keywords: Exoplanet dynamics, Exoplanets, Exoplanet systems, Oblateness, Planetary system formation
Testing the Universality of Self-organized Criticality in Galactic, Extragalactic, and Black Hole Systems. In this study, we test whether the power law slopes (α  F ) for fluxes (F), and (α  E ) for energies (E) are universal in their size distributions,   and  , in astrophysical observations of galactic, extragalactic, and black hole systems. This is a test of fundamental importance for self-organized criticality (SOC) systems. The test decides whether (i) power laws are a natural consequence of the scale-freeness and inherent universality of SOC systems, or (ii) if they depend on more complex physical scaling laws. The former criterion allows quantitative predictions of the power-law-like size distributions, while the latter criterion requires individual physical modeling for each SOC variable and data set. Our statistical test, carried out with 61 published data sets, is consistent with the former option, which implies that observed power laws can simply be derived from the scale-freeness and do not require specific physical models to understand their statistical distributions. The observations show a mean and standard deviation of α  F  = 1.78 ± 0.29 for SOC fluxes and α  E  = 1.66 ± 0.22 for SOC fluences, and thus are consistent with the prediction of the fractal-diffusive SOC model, with α  F  = 1.80 and α  E  = 1.67.

Keywords: AGN host galaxies, X-ray bursts, Gamma-ray bursts, A stars, Solar energetic particles, Blazars, Flare stars, Exoplanet astronomy, Soft gamma-ray repeaters, Radio bursts, Binary pulsars, Astrophysical black holes, Cosmic rays
Combined Fit of Spectrum and Composition for FR0 Radio-galaxy-emitted Ultra–high energy Cosmic Rays with Resulting Secondary Photons and Neutrinos. This study comprehensively investigates the gamma-ray dim population of Fanaroff–Riley Type 0 (FR0) radio galaxies as potentially significant sources of ultra–high energy cosmic rays (UHECRs, E &gt; 1018 eV) detected on Earth. While individual FR0 luminosities are relatively low compared to the more powerful Fanaroff–Riley Type 1 and Type 2 galaxies, FR0s are substantially more prevalent in the local universe, outnumbering the more energetic galaxies by a factor of ∼5 within a redshift of z ≤ 0.05. Employing CRPropa3 simulations, we estimate the mass composition and energy spectra of UHECRs originating from FR0 galaxies for energies above 1018.6 eV. This estimation fits data from the Pierre Auger Observatory (Auger) using three extensive air shower models; both constant and energy-dependent observed elemental fractions are considered. The simulation integrates an approximately isotropic distribution of FR0 galaxies, extrapolated from observed characteristics, with UHECR propagation in the intergalactic medium, incorporating various plausible configurations of extragalactic magnetic fields, both random and structured. We then compare the resulting emission spectral indices, rigidity cutoffs, and elemental fractions with recent Auger results. In total, 25 combined energy-spectrum and mass-composition fits are considered. Beyond the cosmic-ray fluxes emitted by FR0 galaxies, this study predicts the secondary photon and neutrino fluxes from UHECR interactions with intergalactic cosmic photon backgrounds. The multimessenger approach, encompassing observational data and theoretical models, helps elucidate the contribution of low-luminosity FR0 radio galaxies to the total cosmic-ray energy density.

Keywords: Neutrino astronomy, Cosmic ray showers, Low-luminosity active galactic nuclei, Fanaroff-Riley radio galaxies, Cosmic ray sources, Gamma-rays, Ultra-high-energy cosmic radiation, Extragalactic magnetic fields
Testing the Bullet Dwarf Collision Scenario in the NGC 1052 Group through Morphologies and Stellar Populations. NGC 1052-DF2 and -DF4 are two ultradiffuse galaxies that have been reported as deficient in dark matter and associated with the same galaxy group. Recent findings suggest that DF2 and DF4 are part of a large linear substructure of dwarf galaxies that could have been formed from a high-velocity head-on encounter of two gas-rich galaxies, known as a "bullet dwarf" collision. Based on new observations from the Hubble Space Telescope, combined with existing imaging from the u band to mid-infrared, we test the bullet dwarf scenario by studying the morphologies and stellar populations of the trail dwarfs. We find no significant morphological differences between the trail dwarfs and other dwarfs in the group, while for both populations, their photometric major axes unexpectedly align parallel with the trail. We find that the trail dwarfs have significantly older ages and higher metallicities than the comparison sample, supporting the distinctiveness of the trail. These observations provide key constraints for any formation model, and we argue that they are currently best explained by the bullet dwarf collision scenario, with additional strong tests anticipated with future observations.

Keywords: Galaxy formation, Dwarf galaxies, Dark matter
VLA 22 GHz Imaging of Massive Star Formation in Local Wolf–Rayet Galaxies. We present 22 GHz imaging of regions of massive star formation within the Local Wolf–Rayet Galaxy Sample, a NSF Karl G. Jansky Very Large Array survey of 30 local galaxies showing spectral features of Wolf–Rayet (WR) stars. These spectral features are present in galaxies with young super star clusters (SSCs), and are an indicator of large concentrations of massive stars. We present a catalog of 92 individually identified regions of likely free–free emission associated with potential young SSCs located in these WR galaxies. The free–free fluxes from these maps allow extinction-free estimates of the Lyman continuum rates, masses, and luminosities of the emission regions. Thirty-nine of these regions meet the minimum Lyman continuum rate to contain at least once SSC, and 29 of these regions could contain individual SSCs massive enough to test specific theories on star formation and feedback inhibition in SSCs, requiring follow-up observations at higher spatial resolution. The resulting catalog provides sources for future molecular line and IR studies into the properties of SSC formation.

Keywords: Star forming regions, Young massive clusters, Young star clusters, Star formation, Radio continuum emission, H II regions, Star clusters
Central versus Global Quenching Traced by the APEX-CALIFA Survey. The quest for the mechanisms that halt star formation in galaxies is essential to understand their evolution. Here, we use the APEX-CALIFA survey, which includes 560 galaxies (0.005 &lt; z &lt; 0.08), so far the largest sample of galaxies in the nearby universe with both Integral Field Spectroscopic, Calar Alto Legacy Integral Field Area (CALIFA) and single-aperture millimeter observations, as well as the extended CALIFA sample (823 targets). Using these observations we derive (i) the deficit or excess of star formation for a given stellar mass with respect to the star formation main sequence (ΔSFMS), (ii) the gas fraction, and (iii) the star formation efficiency (SFE) for two apertures (central and global apertures using the APEX-CALIFA and CALIFA samples, respectively). We confirm the so-called "inside-out" quenching, that is, for quiescent galaxies the central values of ΔSFMS are usually smaller than those values derived from global measurements. However, for a given ΔSFMS we find that for retired galaxies the central gas fraction is larger in comparison to global measurements. Furthermore, the central SFE is significantly smaller in comparison to global counterparts. In general, in comparison to the global measurements, the deficit of star formation at the center of retired galaxies is primarily caused by the inefficiency to form new stars rather than the lack of molecular gas. We suggest that even though at the center of retired galaxies the gas fraction is larger, morphological structures could prevent that the molecular gas is transformed into new stars. Even more so in the outskirts of some retired galaxies with small gas fractions, star formation activity is still occurring.

Keywords: Molecular gas, Surveys, Star formation, Red sequence galaxies, Galaxy quenching
Decoding the Future of Exoplanets: Asteroseismic Confirmation of Subgiant and Red Giant Hosts. Asteroseismology has emerged as a powerful tool to unravel the intricate relationships between evolved stars and their planetary systems. In this study, we leverage this technique to investigate the evolutionary stages of five exoplanet host stars, each exhibiting solar-like oscillations. Building on our previous work that identified two host stars as red clump and red giant branch (RGB) stars, this study focuses on a new and broader sample. By precisely measuring asteroseismic parameters such as the period spacing of dipole gravity modes (ΔΠ1), we provide definitive confirmation of these stars' evolutionary states as subgiants or RGB stars. These results are not only crucial for understanding the internal structures of evolved stars but also for predicting the eventual fate of their planetary companions, which may face engulfment as their host stars expand. This research highlights the profound role of asteroseismology in advancing our knowledge of planetary system evolution and opens new pathways for exploring how stellar evolution impacts planetary survival. Our findings set the stage for future studies on the dynamic fates of exoplanets, providing key insights into the intricate processes of stellar and planetary evolution.

Keywords: Subgiant stars, Red giant branch, Exoplanets, Planet hosting stars, Asteroseismology
Depolarization by Jet Precession in Early Optical Afterglows of Gamma-Ray Bursts. Polarization observations provide a unique way to probe the nature of jet magnetic fields in gamma-ray bursts (GRBs). Recently, some GRBs have been detected to be polarized in their early optical afterglows. However, the measured polarization degrees (PDs) of these GRBs are much lower than those predicted by theoretical models. In this work, we investigate the depolarization induced by jet precession in combination with the measured PDs of the GRB early optical afterglows in the reverse shock (RS) dominated phase (∼102–103 s). We calculate the PDs of RS emissions with and without jet precession in both magnetic field configurations, i.e., aligned and toroidal magnetic fields, and meanwhile explore the effects of different parameters on the PDs. We find that the PDs are slightly affected by the configurations of the ordered magnetic fields and are positively related to the precession period. Moreover, the PDs are sensitive to the observed angle, and the measured low PDs favor a small one. Thus, as one of the plausible origins of the structured jets, jet precession could be considered as an alternative mechanism for the low PDs observed in GRB early optical afterglows.

Keywords: Shocks, Gamma-ray bursts, Polarimetry, Relativistic jets
Stability of f(Q, B) Gravity via Dynamical System Approach: A Comprehensive Bayesian Statistical Analysis. In this work, we explore the cosmological stability of f(Q, B) gravity using a dynamical system approach, where Q denotes the nonmetricity scalar and B represents the boundary term. We determine the model parameters of f(Q, B) through Bayesian statistical analysis, employing Markov Chain Monte Carlo techniques. This analysis incorporates numerical solutions and observational data from cosmic chronometers, the extended Pantheon+ data set, and baryonic acoustic oscillation measurements. Our findings reveal a stable critical point within the dynamical system of the model, corresponding to the de Sitter phase, which is consistent with current observations of the Universe dominated by dark energy and undergoing late-time accelerated expansion. Additionally, we utilize center manifold theory to examine the stability of this critical point, providing deeper insights into the behavior of the model. The cosmological implications of f(Q, B) gravity indicate a smooth transition in the deceleration parameters from deceleration to the acceleration phase, underscoring the potential of the model to describe the evolution of the Universe. Our results suggests that the f(Q, B) model presents a viable alternative to the standard ΛCDM model, effectively capturing the observed acceleration of the Universe and offering a robust framework for explaining the dynamics of cosmic expansion.

Keywords: Deceleration parameter, Accelerating universe, Cosmological parameters
The Impact of the Angle-average Approximation in the Partial Frequency Redistribution Modeling of the Mg II h–k Doublet Stokes Profiles. In recent years, the Mg II h and k lines have become increasingly important for the diagnostics of magnetic fields in the solar chromosphere, motivated both by the advances in the modeling capabilities of their polarization and by the unprecedented spectropolarimetric observations provided by the CLASP missions. In this paper, we investigate the impact of the angular and frequency coupling in coherent scattering processes in the radiative transfer modeling of the Mg II doublet polarization profiles. In particular, we aim to assess how the widely used angle-average approximation affects the predicted polarization. By solving the radiative transfer problem in 1D semiempirical atmospheric models, we find that this approximation is suitable in the absence of magnetic fields, but there can be measurable differences in magnetized models, mainly in the linear polarization profiles close to the core of the Mg II k line. We then test the suitability of the approximation in more realistic scenarios, solving the radiative transfer problem pixel-by-pixel in a 3D atmospheric model resulting from a magnetohydrodynamic simulation and mimicking the degradation of the CLASP2 instrument, as well as in several 1D atmospheric models resulting from the Stokes inversion of the CLASP2 data. We find that the impact of the angle-average approximation is greatly diminished at the resolution of the CLASP2 observations. We also find that to suitably include angle-dependent effects in 1D radiative transfer modeling, it is sufficient to initialize the problem with the angle-average solution and then perform a few (angle-dependent) iterations, dramatically reducing the computational cost.

Keywords: Solar chromosphere, Spectropolarimetry, Radiative transfer
SOFIA/HAWC+ Far-infrared Polarimetric Large-area CMZ Exploration Survey. IV. Relative Magnetic Field Orientation throughout the CMZ. The nature of the magnetic field structure throughout the Galactic Center (GC) has long been of interest. The recent Far-InfraREd Polarimetric Large-Area Central Molecular Zone (CMZ) Exploration (FIREPLACE) Survey reveals preliminary connections between the seemingly distinct vertical and horizontal magnetic field distributions previously observed in the GC. We use the statistical techniques of the Histogram of Relative Orientation and the Projected Rayleigh Statistic to assess whether the CMZ magnetic field preferentially aligns with the structure of the CMZ molecular clouds or the morphology of the nonthermal emission of the GC nonthermal filament (NTF) population. We find that there is a range of magnetic field orientations throughout the population of CMZ molecular clouds, ranging from parallel to perpendicular orientation. We posit these orientations depend on the prevalence of gravitational shear in the GC, in contrast with what is observed in Galactic Disk star-forming regions. We also compare the magnetic field orientation from dust polarimetry with individual prominent NTFs, finding a preferred perpendicular relative orientation. This perpendicular orientation indicates that the vertical field component found in the FIREPLACE observations is not spatially confined to the NTFs, providing evidence for a more pervasive vertical field in the GC. From dynamical arguments, we estimate an upper limit on the magnetic field strength for this vertical field, finding B ≤ 4 mG. A field close to this upper limit would indicate that the NTFs are not local enhancements of a weaker background field and that the locations of the NTFs depend on proximity to sites of cosmic-ray production.

Keywords: Interstellar dust, Galactic center, Molecular clouds, Interstellar magnetic fields, Star formation, Interstellar synchrotron emission, Polarimetry
Multiwavelength Afterglow Analysis of GRB 221009A: Unveiling the Evolution of a Cooling Break in a Wind-like Medium. Gamma-ray bursts (GRBs) are the most energetic explosions in the Universe, and their afterglow emission provides an opportunity to probe the physics of relativistic shock waves in an extreme environment. Several key pieces for completing the picture of GRB afterglow physics are still missing, including jet properties, the emission mechanism, and particle acceleration. Here, we present a study of the afterglow emission of GRB 221009A, the most energetic GRB ever observed. Using optical, X-ray, and gamma-ray data up to approximately 2 days after the trigger, we trace the evolution of the multiwavelength spectrum and the physical parameters behind the emission process. The broadband spectrum is consistent with the synchrotron emission emitted by relativistic electrons with its index of p = 2.29 ± 0.02. We identify a break energy at keV and an exponential cutoff at GeV in the observed multiwavelength spectrum. The break energy increases in time from   keV at 0.65 days to   keV at 1.68 days, favoring a stellar-wind-like profile of the circumburst medium with k = 2.4 ± 0.1 as in ρ(r) ∝ r ‑k . The high-energy attenuation at around 0.4 to 4 GeV is attributed to the maximum of the particle acceleration in the relativistic shock wave. This study confirms that the synchrotron process can explain the multiwavelength afterglow emission and its evolution.

Keywords: Non-thermal radiation sources, Gamma-ray bursts, Relativistic jets
Self-excited Pulsations and the Instability Strip of Long-period Variables: The Transition from Small-amplitude Red Giants to Semi-regular Variables. We use one-dimensional hydrodynamic calculations combined with synthetic stellar population models of the Magellanic Clouds to study the onset of self-excited pulsation in luminous red giants. By comparing the results with Optical Gravitational Lensing Experiment observations in the period─luminosity (PL) diagram, we are able to link the transition from small-amplitude red giants to semi-regular variables with a shift from stochastic driving to self-excited pulsations. This is consistent with previous studies relating this transition with an increase in mass-loss rate, dust formation, and the appearance of long secondary periods. The luminosity and effective temperature at the onset of pulsation are found to depend on metallicity, hydrogen content, and the adopted mixing length parameter. This confirms the role of partial hydrogen ionization in driving the pulsation, supporting the idea of a heat mechanism similar to that of classical pulsators. We examine the impact of turbulent viscosity, and find clear evidence that it must be adjusted according to the stellar chemical and physical parameters to fully match observations. In order to improve the predictive power of pulsation models, the turbulent viscosity and the temperature scale of pulsating red giants must be jointly calibrated. This is critical for model-based studies of the PL relations of evolved stars and to exploit their potential as distance and age indicators, in particular given the sensitivity of the onset of pulsation to the envelope composition. The grid of models is made publicly available with a companion interpolation routine.

Keywords: Stellar pulsations, Asymptotic giant branch stars, Semi-regular variable stars, OGLE small amplitude red giant stars, Long period variable stars, Red giant stars, Magellanic Clouds
The NANOGrav 15 yr Data Set: Looking for Signs of Discreteness in the Gravitational-wave Background. The cosmic merger history of supermassive black hole binaries (SMBHBs) is expected to produce a low-frequency gravitational wave background (GWB). Here we investigate how signs of the discrete nature of this GWB can manifest in pulsar timing arrays (PTAs) through excursions from, and breaks in, the expected   power law of the GWB strain spectrum. To do this, we create a semianalytic SMBHB population model, fit to North American Nanohertz Observatory for Gravitational Waves (NANOGrav's) 15 yr GWB amplitude, and with 1000 realizations, we study the populations' characteristic strain and residual spectra. Comparing our models to the NANOGrav 15 yr spectrum, we find two interesting excursions from the power law. The first, at 2 nHz, is below our GWB realizations with a p-value significance p = 0.05–0.06 (≈1.8σ–1.9σ). The second, at 16 nHz, is above our GWB realizations with p = 0.04–0.15 (≈1.4σ–2.1σ). We explore the properties of a loud SMBHB that could cause such an excursion. Our simulations also show that the expected number of SMBHBs decreases by 3 orders of magnitude, from ∼106 to ∼103, between 2 and 20 nHz. This causes a break in the strain spectrum as the stochasticity of the background breaks down at  , consistent with predictions pre-dating GWB measurements. The diminished GWB signal from SMBHBs at frequencies above the 26 nHz break opens a window for PTAs to detect continuous GWs from individual SMBHBs or GWs from the early Universe.

Keywords: Gravitational wave astronomy, Supermassive black holes, Gravitational waves, Quasars