Sazuna/UAT_keywords huggingface dataset:
Constraining Inputs to Realistic Kilonova Simulations through Comparison to Observed r-process Abundances. Kilonovae, one source of electromagnetic emission associated with neutron star mergers, are powered by the decay of radioactive isotopes in the neutron-rich merger ejecta. Models for kilonova emission consistent with the electromagnetic counterpart to GW170817 predict characteristic abundance patterns, determined by the relative balance of different types of material in the outflow. Assuming that the observed source is prototypical, this inferred abundance pattern in turn must match r-process abundances deduced by other means, such as what is observed in the solar system. We report on analysis comparing the input mass-weighted elemental compositions adopted in our radiative transfer simulations to the mass fractions of elements in the Sun, as a practical prototype for the potentially universal abundance signature from neutron star mergers. We characterize the extent to which our parameter inference results depend on our assumed composition for the dynamical and wind ejecta and examine how the new results compare to previous work. We find that a dynamical ejecta composition calculated using the FRDM2012 nuclear mass and FRLDM fission models with extremely neutron-rich ejecta (Y e = 0.035) along with moderately neutron-rich (Y e = 0.27) wind ejecta composition yields a wind-to-dynamical mass ratio of M w /M d = 0.47, which best matches the observed AT2017gfo kilonova light curves while also producing the best-matching abundance of neutron capture elements in the solar system, though, allowing for systematics, the ratio may be as high as of order unity.

Keywords: R-process, Nucleosynthesis
Systematic Uncertainties of Atomic Data in Photoionization Modeling. Fitting plasma models to high-quality spectra is a crucial tool for deriving diagnostics about the physical conditions in various astrophysical sources. Despite decades of model development, this prescription often provides an unsatisfying description of observational data. We explore some of the origins of the failure of fits of photoionized plasma models to high-resolution X-ray spectra. In particular, we test whether systematic uncertainties in underlying atomic data can account for data model discrepancies, and whether including model uncertainties during spectral fitting can provide statistically acceptable fits and reasonable parameter estimates. We fit Chandra/HETG spectra of NGC 3783 with the photoionized absorber model warmabs. We use the remaining data model discrepancies to estimate the systematic uncertainties of bound-bound radiative rates for individual transitions quantitatively. We then include these uncertainties into warmabs to return a total model uncertainty. We find residual data model discrepancies which are due to systematic errors that cannot be accounted for solely by a modification of the optical depth of strong absorption lines. Furthermore, statistical uncertainties still dominate the fit statistics. The relevance of model uncertainties in spectral fitting will vary on a case-by-case basis. However, they are likely to have a minor effect on most of the currently existing data sets. We conclude that while the quality of atomic data does have an effect on fitting photoionization models, and so demands further improvement, uncertainties in radiative rates cannot be held solely responsible for statistically unacceptable fits. Other sources of systematic uncertainties are likely to be of comparable importance and require further investigation.

Keywords: Atomic reactions, Photoionization, Laboratory astrophysics, Atomic data
Regulation of Proton-α Differential Flow by Compressive Fluctuations and Ion-scale Instabilities in the Solar Wind. Large-scale compressive slow-mode-like fluctuations can cause variations in the density, temperature, and magnetic-field magnitude in the solar wind. In addition, they also lead to fluctuations in the differential flow U pα  between α-particles and protons (p), which is a common source of free energy for the driving of ion-scale instabilities. If the amplitude of the compressive fluctuations is sufficiently large, the fluctuating U pα  intermittently drives the plasma across the instability threshold, leading to the excitation of ion-scale instabilities and thus the growth of corresponding ion-scale waves. The unstable waves scatter particles and reduce the average value of U pα . We propose that this "fluctuating-drift effect" maintains the average value of U pα  well below the marginal instability threshold. We model the large-scale compressive fluctuations in the solar wind as long-wavelength slow-mode waves using a multi-fluid model. We numerically quantify the fluctuating-drift effect for the Alfvén/ion-cyclotron and fast-magnetosonic/whistler instabilities. We show that measurements of the proton-α differential flow and compressive fluctuations from the Wind spacecraft are consistent with our predictions for the fluctuating-drift effect. This effect creates a new channel for a direct cross-scale energy transfer from large-scale compressions to ion-scale fluctuations.

Keywords: Space plasmas, Solar wind, Heliosphere
Implications of Narrow Spectra of Fast Radio Bursts. Fast radio bursts (FRBs) are millisecond-duration radio transients with extremely high brightness temperatures at cosmological distances, and the physical origin and the radiation mechanism of FRBs are still unknown. The observed spectral bandwidth of some FRBs appeared narrow compared with their peak frequencies, which could be used to constrain the radiation mechanism and the astrophysical environment of FRBs. In this work, we investigate some of the possible physical origins of the narrow spectra from the perspectives of intrinsic radiation mechanisms, coherent processes, radiative transfers, and interference processes. We find that: (1) If the observed narrow spectra of FRBs are attributed to the intrinsic radiation mechanism by a single charged particle, the particle's deflection angle should be much smaller than the radiation beaming angle. (2) Coherent process can cause narrow spectra. For the bunching mechanism, the narrow spectra might arise from the radiating bunches with a quasiperiodic distribution. For the maser mechanism, the negative absorption process can naturally cause a narrow spectrum. (3) Most absorption and scattering processes seem not to significantly change the observed spectra based on the current observation of some FRB repeaters. (4) Scintillation and plasma lensing in the FRB source environment can modulate the spectra, leading to the narrow spectra and the burst-to-burst variation of spectra. A planet-like object can generate the spectral modulation via gravitational lensing at the gigahertz band, but the observed burst-to-burst variation of the spectra does not support this scenario.

Keywords: Neutron stars, Compact radiation sources, Radio bursts, Radiative processes, Radio transient sources
The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. I. Detection of a Rich Population of Dusty Objects in the IRS 13 Cluster. A detailed analysis of the nuclear star cluster not only concedes the existence of the S cluster, with its fast-moving stars and the supermassive black hole Sgr A*. It also reveals an embedded region of gas and dust with an exceptionally high stellar density called IRS 13. The IRS 13 cluster can be divided into the northern and eastern counterparts, called IRS 13N and IRS 13E, respectively. This work will focus on both regions and study their most prominent members using rich infrared and radio/submillimeter data baselines. Applying a multiwavelength analysis enables us to determine a comprehensive photometric footprint of the investigated cluster sample. Using the ray-tracing-based radiative transfer model HYPERION, the spectral energy distribution of the IRS 13 members suggests a stellar nature of the dusty sources. These putative young stellar objects (YSOs) have a comparable spectroscopic identification to the D and G sources in or near the S cluster. Furthermore, we report the existence of a population of dusty sources in IRS 13 that can be mostly identified in the H, K, and L band. We propose that, together with the objects reported in the literature, this population is the outcome of a recent star formation process. Furthermore, we report that these presumably young objects are arranged in a disk structure. Although it cannot be excluded that the intrinsic arrangement of IRS 13 does show a disk structure, we find indications that the investigated cluster sample might be related to the counterclockwise disk.

Keywords: Intermediate-mass black holes, Supermassive black holes, Galactic center, Young massive clusters, Young stellar objects
Abundances and Transients from Neutron Star-White Dwarf Mergers. We systematically investigate the mergers of neutron star-white dwarf binaries from beginning to end, with a focus on the properties of the inflows and outflows in accretion disks and their electromagnetic emissions. Using population synthesis models, we determine a subset of these binaries in which the white dwarf companion undergoes unstable mass transfer and complete tidal disruption, forming a large accretion disk around the neutron star. The material evolves according to a one-dimensional advection-dominated accretion-disk model with nuclear burning, neutrino emissions, and disk-surface wind ejection. The extreme dynamics of the entire process have proven difficult to analyze, and thus currently, the properties are poorly understood. The outflows from the mergers are iron- and nickel-rich, giving rise to optical and infrared emissions powered by the decay of the radioactive iron-type isotopes, calculated via the SuperNu light-curve code. We find these systems capable of powering bright, yet short-lived, optical transients with the potential to power gamma-ray bursts.

Keywords: Neutron stars, Gamma-ray bursts, Light curves, White dwarf stars, Stellar accretion disks
A Near-infrared-faint, Far-infrared-luminous Dusty Galaxy at z ∼ 5 in COSMOS-Web. A growing number of far-infrared (FIR) bright sources completely invisible in deep extragalactic optical surveys hint at an elusive population of z &gt; 4 dusty, star-forming galaxies. Cycle 1 JWST surveys are now detecting their rest-frame optical light, which provides key insight into their stellar properties and statistical constraints on the population as a whole. This work presents the JWST Near Infrared Camera (NIRCam) counterpart from the COSMOS-Web survey to an FIR SCUBA-2 and Atacama Large Millimeter/submillimeter Array (ALMA) source, AzTECC71, which was previously undetected at wavelengths shorter than 850 μm. AzTECC71, among the reddest galaxies in COSMOS-Web with F277W - F444W ~ 0.9, is undetected in NIRCam/F150W and F115W and fainter in F444W than other submillimeter galaxies identified in COSMOS-Web by 2-4 magnitudes. This is consistent with the system having both a lower stellar mass and higher redshift than the median dusty, star-forming galaxy. With deep ground- and space-based upper limits combined with detections in F277W, F444W, and the FIR including ALMA Band 6, we find a high probability (99%) that AzTECC71 is at z &gt; 4 with ${z}_{\mathrm{phot}}={5.7}_{-0.7}^{+0.8}$ . This galaxy is massive ( $\mathrm{log}\,{M}_{* }/{M}_{\odot }\sim 10.7$ ) and infrared-luminous ( $\mathrm{log}\,{L}_{\mathrm{IR}}/{L}_{\odot }\sim 12.7$ ), comparable to other optically undetected but FIR-bright dusty, star-forming galaxies at z &gt; 4. This population of luminous, infrared galaxies at z &gt; 4 is largely unconstrained but comprises an important bridge between the most extreme dust-obscured galaxies and more typical high-redshift star-forming galaxies. If further FIR-selected galaxies that drop out of the F150W filter in COSMOS-Web have redshifts z &gt; 4 like AzTECC71, then the volume density of such sources may be ~3-10 × greater than previously estimated.

Keywords: Ultraluminous infrared galaxies, High-redshift galaxies, Galaxy evolution, Far infrared astronomy
A Fundamental Mechanism of Solar Eruption Initiation in a Multipolar Magnetic Field. Recently, we established a fundamental mechanism of solar eruption initiation in which an eruption can be initiated from a bipolar field through magnetic reconnection in the current sheet (CS) that is formed slowly in the core field as driven by photospheric shearing motion. Here, using a series of fully 3D MHD simulations with a range of different photospheric magnetic flux distributions, we extended this fundamental mechanism to the quadrupolar magnetic field containing a null point above the core field, which is the basic configuration of the classical breakout model. As is commonly believed, in such a multipolar configuration, the reconnection triggered in the CS originated at the null point (namely, the breakout reconnection) plays the key role in eruption initiation by establishing a positive feedback loop between the breakout reconnection and the expansion of the core field. However, our simulation showed that the key to eruption initiation in such a multipolar configuration remains the slow formation of the CS in the sheared core, rather than the onset of fast breakout reconnection. The breakout reconnection only helps the formation of the core CS by letting the core field expand faster, but the eruption cannot occur when the bottom surface driving is stopped well before the core CS is formed, even though the fast reconnection has already been triggered in the breakout CS. This study clarified the role of breakout reconnection and confirmed formation of the core CS as the key to the eruption initiation in a multipolar magnetic field.

Keywords: Magnetohydrodynamics, Solar flares, Solar magnetic fields, Solar coronal mass ejections, Solar corona, Magnetohydrodynamical simulations
On the Effectiveness of the Planetary Infrared Excess (PIE) Technique to Retrieve the Parameters of Multiplanet Systems around M Dwarfs: A Case Study on the TRAPPIST-1 System. The planetary infrared excess (PIE) technique has the potential to efficiently detect and characterize the thermal spectra of both transiting and non-transiting exoplanets. However, the technique has not been evaluated on multiplanet systems. We use the TRAPPIST-1 system as our test bed to evaluate PIE's ability to resolve multiple planets. We follow the unfolding discoveries in the TRAPPIST-1 system and examine the results from the PIE technique at every stage. We test the information gained from observations with JWST and next-generation infrared observatories like the proposed MIRECLE mission concept. We find that even in the case where only the star is known, the PIE technique would infer the presence of multiple planets in the system. The precise number inferred is dependent on the wavelength range of the observation and the noise level of the data. We also find that in such a tightly packed, multiplanet system such as TRAPPIST-1, the PIE technique struggles to constrain the semimajor axis beyond prior knowledge. Despite these drawbacks and the fact that JWST is less sensitive to the fluxes from planets g and h, with strong priors in their orbital parameters we are able to constrain their equilibrium temperatures. We conclude that the PIE technique may enable the discovery of unknown exoplanets around solar-neighborhood M dwarfs and could characterize known planets around them.

Keywords: Extrasolar rocky planets, Exoplanet detection methods, Infrared excess, Exoplanets
Nearby SNR: A Possible Common Origin of Multi-messenger Anomalies in the Spectra, Ratios, and Anisotropy of Cosmic Rays. Multi-messenger anomalies, including spectral hardening or excess of nuclei, leptons, ratios of $\bar{p}/p$ and B/C, and anisotropic reversal, have been observed in past years. The AMS-02 experiment also revealed different spectral breaks for positrons and electrons at 284 GeV and beyond tera electron volts, respectively. It is natural to ask whether all those anomalies originate from one unified physical scenario. In this work, the spatially dependent propagation (SDP) with a nearby supernova remnant (SNR) source is adopted to reproduce the abovementioned anomalies. There possibly exists a dense molecular cloud (DMC) around SNRs and the secondary particles can be produced by pp collision or fragmentation between the accelerated primary cosmic rays and DMC. As a result, the spectral hardening for primary and secondary particles and ratios of B/C and $\bar{p}/p$ can be well reproduced. Due to the energy loss at the source age of 330 kyr, the characteristic spectral break-off for a primary electron is at about 1 TeV as hinted at by the measurements. The secondary positrons and electrons from charged pion take up 5% of energy from their mother particles, so the positron spectrum has a break-off at ~250 GeV. Therefore, the different spectral breaks for positrons and electrons together with other anomalies can be fulfilled in this unified physical scenario. More interesting is that we also obtain the featured structures as spectral break-offs at 5 TeV for secondary particles of Li, Be, and B, which can be used to verify our model. We hope that those tagged structures can be observed by the new generation of spaceborne experiment HERD in the future.

Keywords: Supernova remnants, Secondary cosmic rays, Cosmic ray sources, Cosmic anisotropy
Beyond Two-dimensional Mass–Radius Relationships: A Nonparametric and Probabilistic Framework for Characterizing Planetary Samples in Higher Dimensions. Fundamental to our understanding of planetary bulk compositions is the relationship between their masses and radii, two properties that are often not simultaneously known for most exoplanets. However, while many previous studies have modeled the two-dimensional relationship between planetary mass and radii, this approach largely ignores the dependencies on other properties that may have influenced the formation and evolution of the planets. In this work, we extend the existing nonparametric and probabilistic framework of MRExo to jointly model distributions beyond two dimensions. Our updated framework can now simultaneously model up to four observables, while also incorporating asymmetric measurement uncertainties and upper limits in the data. We showcase the potential of this multidimensional approach to three science cases: (i) a four-dimensional joint fit to planetary mass, radius, insolation, and stellar mass, hinting of changes in planetary bulk density across insolation and stellar mass; (ii) a three-dimensional fit to the California Kepler Survey sample showing how the planet radius valley evolves across different stellar masses; and (iii) a two-dimensional fit to a sample of Class-II protoplanetary disks in Lupus while incorporating the upper limits in dust mass measurements. In addition, we employ bootstrap and Monte Carlo sampling to quantify the impact of the finite sample size as well as measurement uncertainties on the predicted quantities. We update our existing open-source user-friendly MRExo Python package with these changes, which allows users to apply this highly flexible framework to a variety of data sets beyond what we have shown here.

Keywords: Computational methods, Algorithms, Exoplanets, Astrostatistics tools
CLASS Data Pipeline and Maps for 40 GHz Observations through 2022. The Cosmology Large Angular Scale Surveyor (CLASS) is a telescope array that observes the cosmic microwave background over 75% of the sky from the Atacama Desert, Chile, at frequency bands centered near 40, 90, 150, and 220 GHz. This paper describes the CLASS data pipeline and maps for 40 GHz observations conducted from 2016 August to 2022 May. We demonstrate how well the CLASS survey strategy, with rapid (~10 Hz) front-end modulation, recovers the large-scale Galactic polarization signal from the ground: the mapping transfer function recovers ~67% (85%) of EE and BB (VV) power at ℓ = 20 and ~35% (47%) at ℓ = 10. We present linear and circular polarization maps over 75% of the sky. Simulations based on the data imply the maps have a white noise level of $110\,\mu {\rm{K}}\,\mathrm{arcmin}$ and correlated noise component rising at low-ℓ as ℓ -2.4. The transfer-function-corrected low-ℓ component is comparable to the white noise at the angular knee frequencies of ℓ ≈ 18 (linear polarization) and ℓ ≈ 12 (circular polarization). Finally, we present simulations of the level at which expected sources of systematic error bias the measurements, finding subpercent bias for the Λ cold dark matter EE power spectra. Bias from E-to-B leakage due to the data reduction pipeline and polarization angle uncertainty approaches the expected level for an r = 0.01 BB power spectrum. Improvements to the instrument calibration and the data pipeline will decrease this bias.

Keywords: Observational cosmology, Cosmic microwave background radiation, Astronomy data analysis, Early universe
The 107 GHz Methanol Transition Is a Dasar in G0.253+0.016. We present observations of population anti-inversion in the 31 - 40 A + transition of CH3OH (methanol) at 107.013831 GHz toward the Galactic center cloud G0.253+0.016 ("The Brick"). Anti-inversion of molecular level populations can result in absorption lines against the cosmic microwave background (CMB) in a phenomenon known as a "dasar." We model the physical conditions under which the 107 GHz methanol transition dases and determine that dasing occurs at densities below 106 cm-3 and column densities between 1013 and 1016 cm-2. We also find that for this transition, dasing does not strongly depend on the gas kinetic temperature. We evaluate the potential of this tool for future deep galaxy surveys. We note that other works have already reported absorption in this transition (e.g., in NGC 253), but we provide the first definitive evidence that it is absorption against the CMB rather than against undetected continuum sources.

Keywords: Galactic center, Astrophysical masers, Molecular clouds
The Radiation Environments of Middle-aged F-type Stars. Far-ultraviolet (FUV) emission lines from dwarf stars are important driving sources of photochemistry in planetary atmospheres. Properly interpreting spectral features of planetary atmospheres critically depends on the emission of its host star. While the spectral energy distributions (SEDs) of K- and M-type stars have been extensively characterized by previous observational programs, the full X-ray to infrared SED of F-type stars has not been assembled to support atmospheric modeling. On the second flight of the Suborbital Imaging Spectrograph for Transition-region Irradiance from Nearby Exoplanet host stars (SISTINE-2) rocket-borne spectrograph, we successfully captured the FUV spectrum of Procyon A (F5 IV-V) and made the first simultaneous observation of several emission features across the FUV bandpass (1010-1270 and 1300-1565 Å) of any cool star. We combine flight data with stellar models and archival observations to develop the first SED of a mid-F star. We model the response of a modern Earth-like exoplanet's upper atmosphere to the heightened X-ray and extreme UV radiation within the habitable zone of Procyon A. These models indicate that this planet would not experience significant atmospheric escape. We simulate observations of the Lyα transit signal of this exoplanet with the Hubble Space Telescope (HST) and the Habitable Worlds Observatory (HWO). While marginally detectable with HST, we find that H I Lyα transits of potentially habitable exoplanets orbiting high radial velocity F-type stars could be observed with HWO for targets up to 150 pc away.

Keywords: Hubble Space Telescope, Ultraviolet spectroscopy, Space observatories, Astronomical instrumentation, Spectral energy distribution, Radiative transfer, Late-type dwarf stars, Exoplanet atmospheres