Sazuna/UAT_keywords huggingface dataset:
Action-angle Variables for Axisymmetric Potentials via Birkhoff Normalization. We describe a method for calculating action-angle (AA) variables in axisymmetric galactic potentials using Birkhoff normalization, a technique from Hamiltonian perturbation theory. An advantageous feature of this method is that it yields explicit series expressions for both the forward and inverse transformations between the AA variables and position–velocity data. It also provides explicit expressions for the Hamiltonian and dynamical frequencies as functions of the action variables. We test this method by examining orbits in a Milky Way model potential and compare it to the popular Stäckel approximation method. When vertical actions are not too large, the Birkhoff normalization method achieves fractional errors smaller than a part in 103 and outperforms the Stäckel approximation. We also show that the range over which Birkhoff normalization provides accurate results can be extended by constructing Padé approximants from the perturbative series expressions developed with the method. Numerical routines in Python for carrying out the Birkhoff normalization procedure are made available.

Keywords: Galaxy dynamics
Eccentricity Estimation for Five Binary Black Hole Mergers with Higher-order Gravitational-wave Modes. The detection of orbital eccentricity for a binary black hole system via gravitational waves is a key signature to distinguish between the possible binary origins. The identification of eccentricity has been difficult so far due to the limited availability of eccentric gravitational waveforms over the full range of black hole masses and eccentricities. Here we evaluate the eccentricity of five black hole mergers detected by the LIGO and Virgo observatories using the TEOBResumS-DALI, TEOBResumS-GIOTTO, and TEOBResumSP models. This analysis studies eccentricities up to 0.6 at the reference frequency of 5 Hz and incorporates higher-order gravitational-wave modes critical to model emission from highly eccentric orbits. The binaries have been selected due to previous hints of eccentricity or due to their unusual mass and spin. While other studies found marginal evidence for eccentricity for some of these events, our analyses do not favor the incorporation of eccentricity compared to the quasi-circular case. While lacking the eccentric evidence of other analyses, we find our analyses marginally shifts the posterior in multiple parameters for several events when allowing eccentricity to be nonzero.

Keywords: Stellar mass black holes, Gravitational waves, Eccentricity
A New Constraint on the Relative Disorder of Magnetic Fields between Neutral Interstellar Medium Phases. Utilizing Planck polarized dust emission maps at 353 GHz and large-area maps of the neutral hydrogen (H I) cold neutral medium (CNM) fraction (f CNM), we investigate the relationship between dust polarization fraction (p 353) and f CNM in the diffuse high latitude ( b&gt;30° ) sky. We find that the correlation between p 353 and f CNM is qualitatively distinct from the p 353–H I column density (N H I ) relationship. At low column densities (N H I  &lt; 4 × 1020 cm‑2) where p 353 and N H I  are uncorrelated, there is a strong positive p 353–f CNM correlation. We fit the p 353–f CNM correlation with data-driven models to constrain the degree of magnetic field disorder between phases along the line of sight. We argue that an increased magnetic field disorder in the warm neutral medium (WNM) relative to the CNM best explains the positive p 353–f CNM correlation in diffuse regions. Modeling the CNM-associated dust column as being maximally polarized, with a polarization fraction p CNM ∼ 0.2, we find that the best-fit mean polarization fraction in the WNM-associated dust column is 0.22p CNM. The model further suggests that a significant f CNM-correlated fraction of the non-CNM column (an additional 18.4% of the H I mass on average) is also more magnetically ordered, and we speculate that the additional column is associated with the unstable medium. Our results constitute a new large-area constraint on the average relative disorder of magnetic fields between the neutral phases of the interstellar medium, and are consistent with the physical picture of a more magnetically aligned CNM column forming out of a disordered WNM.

Keywords: Interstellar magnetic fields, Interstellar dust, Cold neutral medium, Interstellar medium
Metallicity Dependence of Pressure-regulated Feedback-modulated Star Formation in the TIGRESS-NCR Simulation Suite. We present a new suite of numerical simulations of the star-forming interstellar medium (ISM) in galactic disks using the TIGRESS-NCR framework. Distinctive aspects of our simulation suite are (1) sophisticated and comprehensive numerical treatments of essential physical processes including magnetohydrodynamics, self-gravity, and galactic differential rotation, as well as photochemistry, cooling, and heating coupled with direct ray-tracing UV radiation transfer and resolved supernova feedback and (2) wide parameter coverage including the variation in metallicity over  Z'≡Z/Z⊙∼0.1-3 , gas surface density Σgas ∼ 5–150 M ⊙ pc‑2, and stellar surface density Σstar ∼ 1–50 M ⊙ pc‑2. The range of emergent star formation rate surface density is ΣSFR ∼ 10‑4–0.5 M ⊙ kpc‑2 yr‑1, and ISM total midplane pressure is P tot/k  B  = 103–106 cm‑3 K, with P tot equal to the ISM weight  W . For given Σgas and Σstar, we find  ΣSFR∝Z'0.3 . We provide an interpretation based on the pressure-regulated feedback-modulated (PRFM) star formation theory. The total midplane pressure consists of thermal, turbulent, and magnetic stresses. We characterize feedback modulation in terms of the yield ϒ, defined as the ratio of each stress to ΣSFR. The thermal feedback yield varies sensitively with both weight and metallicity as  ϒth∝W‑0.46Z'‑0.53 , while the combined turbulent and magnetic feedback yield shows weaker dependence  ϒturb+mag∝W‑0.22Z'‑0.18 . The reduction in ΣSFR at low metallicity is due mainly to enhanced thermal feedback yield, resulting from reduced attenuation of UV radiation. With the metallicity-dependent calibrations we provide, PRFM theory can be used for a new subgrid star formation prescription in cosmological simulations where the ISM is unresolved.

Keywords: Galaxy formation, Stellar feedback, Star formation, Interstellar medium, Radiative transfer simulations, Metallicity, Magnetohydrodynamical simulations
The Universe SPHEREx Will See: Empirically Based Galaxy Simulations and Redshift Predictions. We simulate galaxy properties and redshift estimation for SPHEREx, the next NASA Medium Class Explorer. To make robust models of the galaxy population and test the spectrophotometric redshift performance for SPHEREx, we develop a set of synthetic spectral energy distributions based on detailed fits to COSMOS2020 photometry spanning 0.1–8 μm. Given that SPHEREx obtains low-resolution spectra, emission lines will be important for some fraction of galaxies. Here, we expand on previous work, using better photometry and photometric redshifts from COSMOS2020 and tight empirical relations to predict robust emission-line strengths and ratios. A second galaxy catalog derived from the GAMA survey is generated to ensure the bright (m  AB  &lt; 18 in the i band) sample is representative over larger areas. Using template fitting to estimate photometric continuum redshifts, we forecast the recovery of 19 million galaxies over 30,000 deg2 with redshifts better than σ  z  &lt; 0.003(1 + z), 445 million with σ  z  &lt; 0.1(1 + z), and 810 million with σ  z  &lt; 0.2(1 + z). We also find through idealized tests that emission-line information from spectrally dithered flux measurements can yield redshifts with accuracy beyond that implied by the naive SPHEREx channel resolution, motivating the development of a hybrid continuum–line redshift estimation approach.

Keywords: Cosmology, Large-scale structure of the universe, Emission line galaxies, Redshift surveys, Spectrophotometry
Chemical Doppelgangers in GALAH DR3: The Distinguishing Power of Neutron-capture Elements among Milky Way Disk Stars. The observed chemical diversity of Milky Way stars places important constraints on Galactic chemical evolution and the mixing processes that operate within the interstellar medium. Recent works have found that the chemical diversity of disk stars is low. For example, the Apache Point Observatory Galactic Evolution Experiment (APOGEE) "chemical doppelganger rate," or the rate at which random pairs of field stars appear as chemically similar as stars born together, is high, and the chemical distributions of APOGEE stars in some Galactic populations are well-described by two-dimensional models. However, limited attention has been paid to the heavy elements (Z &gt; 30) in this context. In this work, we probe the potential for neutron-capture elements to enhance the chemical diversity of stars by determining their effect on the chemical doppelganger rate. We measure the doppelganger rate in GALactic Archaeology with HERMES DR3, with abundances rederived using The Cannon, and find that considering the neutron-capture elements decreases the doppelganger rate from ∼2.2% to 0.4%, nearly a factor of 6, for stars with ‑0.1 &lt; [Fe/H] &lt; 0.1. While chemical similarity correlates with similarity in age and dynamics, including neutron-capture elements does not appear to select stars that are more similar in these characteristics. Our results highlight that the neutron-capture elements contain information that is distinct from that of the lighter elements and thus add at least one dimension to Milky Way abundance space. This work illustrates the importance of considering the neutron-capture elements when chemically characterizing stars and motivates ongoing work to improve their atomic data and measurements in spectroscopic surveys.

Keywords: Galactic archaeology, Chemical abundances, Galaxy chemical evolution
The Escape Velocity Profile of the Milky Way from Gaia DR3. The escape velocity profile of the Milky Way offers a crucial and independent measurement of its underlying mass distribution and dark matter (DM) properties. Using a sample of stars from the third data release of Gaia with 6D kinematics and strict quality cuts, we obtain an escape velocity profile of the Milky Way from 4 to 11 kpc in Galactocentric radius. To infer the escape velocity in radial bins, we model the tail of the stellar speed distribution with both traditional power-law models and a new functional form that we introduce. While power-law models tend to rely on extrapolation to high speeds, we find our new functional form gives the most faithful representation of the observed distribution. Using this for the escape velocity profile, we constrain the properties of the Milky Way's DM halo modeled as a Navarro–Frenck–White profile. Combined with constraints from the circular velocity at the solar position, we obtain a concentration and mass of  c200cDM=13.9‑4.3+6.2  and  M200cDM=0.55‑0.14+0.15×1012M⊙ . This corresponds to a total Milky Way mass of  M200c=0.64‑0.14+0.15×1012M⊙ , which is on the low end of the historic range of the galaxy's mass, but in line with other recent estimates.

Keywords: Stellar kinematics, Galaxy stellar halos, Milky Way dynamics
Rotation and Hα Emission in a Young SMC Cluster: A Spectroscopic View of NGC 330. We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff of the young (∼40 Myr) Small Magellanic Cloud globular cluster NGC 330. Spectra were obtained with the Michigan/Magellan Fiber System and Magellan Inamori Kyocera Echelle spectrographs located on the Magellan-Clay 6.5 m telescope. These spectra revealed the presence of Be stars, occupying primarily the cool side of the split main sequence. Rotational velocity ( vsini ) measurements for most of the targets are consistent with the presence of two populations of stars in the cluster: one made up of rapidly rotating Be stars ( &lt;vsini&gt;≈200  km s‑1) and the other consisting of warmer stars with slower rotation ( &lt;vsini&gt;≈50  km s‑1). Core emission in the Hδ photospheric lines was observed for most of the Hα emitters. The shell parameter computed for the targets in our sample indicates that most of the observed stars should have inclinations below 75°. These results confirm the detection of Be stars obtained through photometry but also reveal the presence of narrow Hα and Hδ features for some targets that cannot be detected with low-resolution spectroscopy or photometry. Asymmetry variability of Hα line profiles on the timescales of a few years is also observed and could provide information on the geometry of the decretion disks. Observations revealed the presence of nebular Hα emission, strong enough in faint targets to compromise the extraction of spectra and to impact narrow-band photometry used to assess the presence of Hα emission.

Keywords: Globular star clusters, Be stars, Star clusters
Formation of Galactic Disks. II. The Physical Drivers of Disk Spin-up. Using a representative sample of Milky Way (MW)–like galaxies from the TNG50 cosmological simulation, we investigate physical processes driving the formation of galactic disks. A disk forms as a result of the interplay between inflow and outflow carrying angular momentum in and out of the galaxy. Interestingly, the inflow and outflow have remarkably similar distributions of angular momentum, suggesting an exchange of angular momentum and/or outflow recycling, leading to continuous feeding of prealigned material from the corotating circumgalactic medium. We show that the disk formation in TNG50 is correlated with stellar bulge formation, in qualitative agreement with a recent theoretical model of disk formation facilitated by steep gravitational potentials. Disk formation is also correlated with the formation of a hot circumgalactic halo with around half of the inflow occurring at subsonic and transonic velocities corresponding to Mach numbers of ≲2. In the context of recent theoretical works connecting disk settling and hot halo formation, our results imply that the subsonic part of the inflow may settle into a disk while the remaining supersonic inflow will perturb this disk via the chaotic cold accretion. We find that disks tend to form when the host halos become more massive than ∼(1–2) × 1011 M ⊙, consistent with previous theoretical findings and observational estimates of the predisk protogalaxy remnant in the MW. Our results do not prove that either corotating outflow recycling, gravitational potential steepening, or hot halo formation cause disk formation, but they show that all these processes occur concurrently and may play an important role in disk growth.

Keywords: Galaxy formation, Galaxy disks, Milky Way disk, Star formation, Magnetohydrodynamical simulations
Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-Ray Polarimetry Explorer. We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3σ level. However, we placed upper limits on the polarization degree at ∼10%─30%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns.

Keywords: X-ray astronomy, Spectropolarimetry, Blazars, Flat-spectrum radio quasars, Radio loud quasars, X-ray quasars, Polarimetry
A Search for Soft X-Ray Emission Lines in the Afterglow Spectrum of GRB 221009A. GRB 221009A was the brightest gamma-ray burst (GRB) of all time (BOAT), surpassing in prompt brightness all GRBs discovered in ∼50 yr and in afterglow brightness in ∼20 yr. We observed the BOAT with XMM-Newton 2.3 days after the prompt. The X-ray afterglow was still very bright and we collected the largest number of photons with the reflection grating spectrometers (RGSs) on a GRB. We searched the RGS data for narrow emission or absorption features. We did not detect any bright line feature. A candidate narrow feature is identified at a (rest-frame) energy of  1.455−0.014+0.006  keV, consistent with an Mg XII K  α  emission line, slightly redshifted (0.012) with respect to the host galaxy. We assessed a marginal statistical significance of 3.0σ for this faint feature based on conservative Monte Carlo simulations, which requires caution for any physical interpretation. If this line feature would be for real, we propose that it might originate from the reflection in the innermost regions of the infalling funnel from low-level late-time activity emission of the central engine.

Keywords: Gamma-ray bursts
An Extragalactic Widefield Search for Technosignatures with the Murchison Widefield Array. It is common for surveys that are designed to find artificial signals generated by distant civilizations to focus on galactic sources. Recently, researchers have started focusing on searching for all other sources within the field observed, including the vast population of background galaxies. Toward a population of galaxies in the background toward the Vela supernova remnant, we search for technosignatures, spectral and temporal features consistent with our understanding of technology. We set transmitter power limits for the detection of signals in a population of over 1300 galaxies within a single field of view observed with the Murchison Widefield Array.

Keywords: Extragalactic astronomy, Extragalactic radio sources, Technosignatures, Exoplanets
On the (Higher Multipoles) Variance Asymmetry in the Cosmic Microwave Background. We have studied the cosmic microwave background (CMB) map looking for features beyond cosmological isotropy. We began by tiling the CMB variance maps (which are produced by different smoothing scales) with stripes of different sizes along the most prominent dipole direction. We were able to confirm previous findings regarding the significance of the dipole. Furthermore, we discovered that some of the higher multipoles exhibit significance comparable to the dipole that naturally depends on the smoothing scales. In the end, we discussed this result having an eye on the look-elsewhere-effect. We believe our results may indicate an anomalous patch in the CMB sky that warrants further investigation.

Keywords: Cosmic microwave background radiation
Pulsar Population Synthesis with Magnetorotational Evolution: Constraining the Decay of the Magnetic Field. We present a population synthesis model for normal radio pulsars in the Galaxy incorporating the latest developments in the field and the magnetorotational evolution processes. Our model considers spin-down with a force-free magnetosphere and the decay of the magnetic field strength and its inclination angle. The simulated pulsar population is fit to a large observation sample that covers the majority of radio surveys using the Markov Chain Monte Carlo technique. We compare the distributions of four major observables—spin period (P), spin-down rate ( Ṗ ), dispersion measure, and radio flux density—using accurate high-dimensional Kolmogorov–Smirnov statistics. We test two B-field decay scenarios, an exponential model motivated by ohmic dissipation and a power-law model motivated by the Hall effect. The former clearly provides a better fit, and it can successfully reproduce the observed pulsar distributions with a decay timescale of  8.3‑3.0+3.9  Myr. The result suggests that significant B-field decay in aged pulsars and ohmic dissipation could be the dominant process.

Keywords: Neutron stars, Radio pulsars, Pulsars
Inversion for Inferring Solar Meridional Circulation: The Case with Constraints on Angular Momentum Transport inside the Sun. We have carried out inversions of travel times as measured by Gizon et al. to infer the internal profile of the solar meridional circulation (MC). A linear inverse problem has been solved by the regularized least-squares method with a constraint that the angular momentum (AM) transport by MC should be equatorward (HK21-type constraint). Our motivation for using this constraint is based on the result by Hotta &amp; Kusano (hereafter HK21), where the solar equator-fast rotation was reproduced successfully without any manipulation. The inversion result indicates that the MC profile is a double-cell structure if the so-called HK21 regime, in which AM transported by MC sustains the equator-fast rotation, correctly describes the physics inside the solar convective zone. The sum of the squared residuals computed with the inferred double-cell MC profile is comparable to that computed with the single-cell MC profile obtained when we exclude the HK21-type constraint, showing that both profiles can explain the data more or less at the same level. However, we also find that adding the HK21-type constraint degrades the resolution of the averaging kernels. Although it is difficult for us to determine the large-scale morphology of the solar MC at the moment, our attempt highlights the relevance of investigating the solar MC profile from both theoretical and observational perspectives.

Keywords: Helioseismology, Solar convective zone, Solar meridional circulation, Solar interior
A New Puzzling Periodic Signal in GeV Energies of the γ-Ray Binary LS I+61°303. LS I+61°303 is a high-mass X-ray binary system comprising a massive Be star and a rapidly rotating neutron star. Its spectral energy distribution across multiwavelengths categorizes it as a γ-ray binary system. In our analysis of LS I+61°303 using Fermi Large Area Telescope observations, we not only confirmed the three previously discussed periodicities of orbital, superorbital, and orbital–superorbital beat periods observed in multiwavelength observations, but also identified an additional periodic signal. This newly discovered signal exhibits a period of ∼26.3 days at a ∼7σ confidence level. Moreover, the power spectrum peak of the new signal gradually decreases as the energy increases across the energy ranges of 0.1–0.3, 0.3–1.0, and 1.0–500.0 GeV. Interestingly, a potential signal with a similar period was found in data obtained from the Owens Valley Radio Observatory 40 m telescope. We suggest that the newly discovered periodic signal may originate from a coupling between the orbital period and the retrograde stellar precession period.

Keywords: Gamma-ray sources, Periodic variable stars, Gamma-rays
Differential Rotation of CoRoT Stars and a Kepler Binary Star from Starspot Transit Mapping. While direct magnetic field measurements are rare for slowly rotating stars, spots observed during planetary transits provide a potential indicator of magnetic activity on stellar surfaces. Moreover, the rotation of the stellar surface can be probed by monitoring the spots' position with time in subsequent transits. This study investigates the dynamic interplay of rotational shear and stellar rotation rate in six stars of spectral types F to M, all hosting exoplanets observed by the CoRoT space mission, except for one binary star from Kepler. The analysis, facilitated by the ECLIPSE code, unveils the physical properties of stellar spots, including radius, intensity, temperature, and position. The five CoRoT stars exhibit spot characteristics consistent with those observed in solar type stars. The determination of a spot longitude during different transits allows for the inference of the star's differential rotation profile, revealing a decreasing trend of rotational shear with the mean stellar rotation period, given by  ΔΩ∝P¯‑0.9 . This implies that, at least for slow rotators (mean rotation period &gt;5 days), as stars age, their differential rotation decreases. Additionally, the six stars analyzed here seem to fall into two categories, according to their spot flux deficit: those with ΔF spot &gt; 0.005 and those with ΔF spot &lt; 0.002.

Keywords: Starspots, Solar differential rotation, Exoplanets, Stellar activity, Stellar rotation