Sazuna/UAT_keywords huggingface dataset:
CEERS Key Paper. V. Galaxies at 4 &lt; z &lt; 9 Are Bluer than They Appear–Characterizing Galaxy Stellar Populations from Rest-frame ∼1 μm Imaging. We present results from the Cosmic Evolution Early Release Survey on the stellar population parameters for 28 galaxies with redshifts 4 &lt; z &lt; 9 using imaging data from the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) combined with data from the Hubble Space Telescope and the Spitzer Space Telescope. The JWST/MIRI 5.6 and 7.7 μm data extend the coverage of the rest-frame spectral energy distribution to nearly 1 μm for galaxies in this redshift range. By modeling the galaxies' SEDs the MIRI data show that the galaxies have, on average, rest-frame UV (1600 Å)—I-band colors 0.4 mag bluer than derived when using photometry that lacks MIRI. Therefore, the galaxies have lower ratios of stellar mass to light. The MIRI data reduce the stellar masses by dex at 4 &lt; z &lt; 6 and 0.37 dex at 6 &lt; z &lt; 9. This also reduces the star formation rates (SFRs) by &lt;ΔlogSFR&gt; = 0.14 dex at 4 &lt; z &lt; 6 and 0.27 dex at 6 &lt; z &lt; 9. The MIRI data also improve constraints on the allowable stellar mass formed in early star formation. We model this using a star formation history that includes both a "burst" at z  f  = 100 and a slowly varying ("delayed-τ") model. The MIRI data reduce the allowable stellar mass by 0.6 dex at 4 &lt; z &lt; 6 and by ≈1 dex at 6 &lt; z &lt; 9. Applying these results globally, this reduces the cosmic stellar-mass density by an order of magnitude in the early Universe (z ≈ 9). Therefore, observations of rest-frame ≳1 μm are paramount for constraining the stellar-mass buildup in galaxies at very high redshifts.

Keywords: Cosmology, Galaxy formation, Galaxy properties, Galaxy colors, Galaxy evolution, Spectral energy distribution, Galaxy masses
Compressible Turbulence in the Near-Sun Solar Wind: Parker Solar Probe's First Eight Perihelia. Many questions remain about the compressibility of solar wind turbulence with respect to its origins and properties. Low plasma beta (ratio of thermal to magnetic pressure) environments allow for the easier generation of compressible turbulence, enabling study of the relationship between density fluctuations and turbulent Mach number. Utilizing Parker Solar Probe plasma data, we examine the normalized proton density fluctuations $\langle \delta {n}_{p}^{2}{\rangle }^{1/2}/\langle {n}_{p}\rangle =\delta {{n}_{p}}_{\mathrm{rms}}/\langle {n}_{p}\rangle $ as a function of turbulent Mach number M  t  conditioned on plasma beta and cross helicity. With consideration of statistical error in the parameters computed from in situ data, we find a general result that $\delta {{n}_{p}}_{\mathrm{rms}}/\langle {n}_{p}\rangle \sim {M}_{t}^{1.18\pm 0.04}$ , consistent with both linear-wave theory and nearly incompressible turbulence in an inhomogeneous background field. We compare observational results conditioned on plasma beta and cross helicity with 3D magnetohydrodynamic simulations and observe rather significant similarities with respect to how those parameters affect the proportionality between density fluctuations and turbulent Mach number. This study further investigates the complexity of compressible turbulence as viewed by the density scaling relationship and may help better understand the compressible environment of the near-Sun solar wind.

Keywords: Interplanetary turbulence, Space plasmas, Plasma physics
True Polar Wander of Lava Worlds. As one of the most detectable types of terrestrial planets, lava worlds are highly prioritized targets for exoplanet atmosphere characterization since their atmospheres may reveal what they are made of and how. Our work examines the possibility of true polar wander (TPW) occurring on these ultrahot tidally locked planets, powered by mass redistribution from atmospheric flow between the hot permanent dayside and the cold permanent nightside. We find that lava planets within a certain mass and temperature range may undergo TPW, and this likelihood increases with star mass. As a result of TPW, the magma ocean and atmospheric compositions may be less evolved (refractory-enriched) than previously thought and may be validated by exoplanet demographic surveys.

Keywords: Exoplanet evolution, Exoplanet atmospheres, Exoplanet atmospheric evolution
The Period Distribution of Hot Jupiters Is Not Dependent on Host Star Metallicity. The probability that a Sun-like star has a close-orbiting giant planet (period ≲1 yr) increases with stellar metallicity. Previous work provided evidence that the period distribution of close-orbiting giant planets is also linked to metallicity, hinting that there two formation/evolution pathways for such objects, one of which is more probable in high-metallicity environments. Here, we check for differences in the period distribution of hot Jupiters (P &lt; 10 days) as a function of host star metallicity, drawing on a sample of 232 transiting hot Jupiters and homogeneously derived metallicities from Gaia Data Release 3. We found no evidence for any metallicity dependence; the period distributions of hot Jupiters around metal-poor and metal-rich stars are indistinguishable. As a byproduct of this study, we provide transformations between metallicities from the Gaia Radial Velocity Spectrograph and from traditional high-resolution optical spectroscopy of main-sequence FGK stars.

Keywords: Hot Jupiters, Exoplanets
Evidence for Two Distinct Populations of Kilonova-associated Gamma-Ray Bursts. Identification of gamma-ray burst (GRB) progenitors based on the duration of their prompt emission (T 90) has faced several roadblocks recently. Long-duration GRBs (with T 90 &gt; 2 s) have traditionally been thought to be originating from the collapse of massive stars and the short-duration ones (with T 90 &lt; 2 s) from compact binary mergers. However, recent observations of a long GRB associated with a kilonova (KN) and a short GRB with supernova association demand a more detailed classification of the GRB population. In this Letter, we focus on GRBs associated with KNe, believed to be originating from mergers of binaries involving neutron stars (NSs). We make use of the GRB prompt-emission light curves of the Swift/BAT 2022 GRB catalog and employ machine-learning algorithms to study the classification of GRB progenitors. Our analysis reveals that there are five distinct clusters of GRBs, of which the KN-associated GRBs are located in two separate clusters, indicating they may have been produced by different progenitors. We argue that these clusters may be due to subclasses of binary neutron star and/or NS-black hole mergers. We also discuss the implications of these findings for future gravitational-wave observations and how those observations may help in understanding these clusters better.

Keywords: Gamma-ray bursts, Gamma-ray transient sources
An Extremely Compact, Low-mass Galaxy on its Way to Quiescence at z = 5.2. We report the discovery of a low-mass z = 5.200 ± 0.002 galaxy that is in the process of ceasing its star formation. The galaxy, MACS0417-z5BBG, is multiply imaged with magnification factors ~40 by the galaxy cluster MACS J0417.5-1154, observed as part of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS). Using observations of MACS0417-z5BBG with a JWST/NIRSpec Prism spectrum and NIRCam imaging, we investigate the mechanism responsible for the cessation of star formation of the galaxy and speculate about possibilities for its future. Using spectrophotometric fitting, we find a remarkably low stellar mass of ${M}_{* }=4.3{\pm }_{0.8}^{0.9}\times {10}^{7}{M}_{\odot }$ , less than 1% of the characteristic stellar mass at z ~ 5. We measure a delensed rest-UV half-light radius in the source plane of $30{\pm }_{5}^{7}$ pc and measure a star formation rate from Hα of $0.14{\pm }_{0.12}^{0.17}$ M ⊙ yr-1. We find that under the assumption of a double power-law star formation history, MACS0417-z5BBG has seen a recent rise in star formation, peaking ~10-30 Myr ago and declining precipitously since then. Together, these measurements reveal a low-mass, extremely compact galaxy which is in the process of ceasing star formation. We investigate the possibilities of mechanisms that have led to the cessation of star formation in MACS0417-z5BBG, considering stellar and active galactic nuclei (AGN) feedback and environmental processes. We can likely rule out most environmental processes but leave open the possibility of a low-mass AGN that does not leave a broad-line imprint on the spectrum or that MACS0417-z5BBG could be a star-forming galaxy in the lull of a bursty star formation history.

Keywords: Post-starburst galaxies, Galaxies
Exploring Proxies for the Supermassive Black Hole Mass Function: Implications for Pulsar Timing Arrays. Supermassive black holes (SMBHs) reside at the center of every massive galaxy in the local universe with masses that closely correlate with observations of their host galaxy, implying a connected evolutionary history. The population of binary SMBHs, which form following galaxy mergers, is expected to produce a gravitational-wave background (GWB) detectable by pulsar timing arrays (PTAs). PTAs are starting to see hints of what may be a GWB, and the amplitude of the emerging signal is toward the higher end of model predictions. Simulated populations of binary SMBHs can be constructed from observations of galaxies and are used to make predictions about the nature of the GWB. The greatest source of uncertainty in these observation-based models comes from the inference of the SMBH mass function, which is derived from observed host galaxy properties. In this paper, I undertake a new approach for inferring the SMBH mass function, starting from a velocity dispersion function rather than a galaxy stellar mass function. I argue that this method allows for a more direct inference by relying on a larger suite of individual galaxy observations as well as relying on a more "fundamental" SMBH mass relation. I find that the resulting binary SMBH population contains more massive systems at higher redshifts than previous models. Additionally, I explore the implications for the detection of individually resolvable sources in PTA data.

Keywords: Supermassive black holes, Gravitational waves, Galaxy mergers, Gravitational wave sources
CEERS Spectroscopic Confirmation of NIRCam-selected z ≳ 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of Their Properties. We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 - 13 and M UV ∈ [ -21, -18] newly identified in NIRCam images in the Cosmic Evolution Early Release Science Survey. We confirm emission line redshifts for 7 galaxies at z = 7.762-8.998 using spectra at ~1-5 μm either with the NIRSpec prism or its three medium-resolution (R ~ 1000) gratings. For z ≃ 9 photometric candidates, we achieve a high confirmation rate of ≃90%, which validates the classical dropout selection from NIRCam photometry. No robust emission lines are identified in three galaxy candidates at z &gt; 10, where the strong [O III] and Hβ lines would be redshifted beyond the wavelength range observed by NIRSpec, and the Lyα continuum break is not detected with the sensitivity of the current data. Compared with Hubble Space Telescope-selected bright galaxies (M UV ≃ -22) that are similarly spectroscopically confirmed at z ≃ 8 - 9, these NIRCam-selected galaxies are characterized by lower star formation rates (SFRs; SFR ≃ 4 M ⊙ yr-1) and lower stellar masses (≃108 M ⊙), but with higher specific SFR (≃40 Gyr-1), higher [O III]+Hβ equivalent widths (≃1100 Å), and elevated production efficiency of ionizing photons ( $\mathrm{log}({\xi }_{\mathrm{ion}}/\mathrm{Hz}\,{\mathrm{erg}}^{-1})\simeq 25.8$ ) induced by young stellar populations (&lt;10 Myr) accounting for ≃20% of the galaxy mass, highlighting the key contribution of faint galaxies to cosmic reionization. Taking advantage of the homogeneous selection and sensitivity, we also investigate metallicity and ISM conditions with empirical calibrations using the [O III]5008/Hβ ratio. We find that galaxies at z ≃ 8 - 9 have higher SFRs and lower metallicities than galaxies at similar stellar masses at z ≃ 2 - 6, which is generally consistent with the current galaxy formation and evolution models.

Keywords: Early universe, Galaxy formation, High-redshift galaxies, Galaxy evolution
Deep Synoptic Array Science: Two Fast Radio Burst Sources in Massive Galaxy Clusters. The hot gas that constitutes the intracluster medium (ICM) has been studied at X-ray and millimeter/submillimeter wavelengths (Sunyaev-Zel'dovich effect) for decades. Fast radio bursts (FRBs) offer an additional method of directly measuring the ICM and gas surrounding clusters via observables such as dispersion measure (DM) and Faraday rotation measure. We report the discovery of two FRB sources detected with the Deep Synoptic Array whose host galaxies belong to massive galaxy clusters. In both cases, the FRBs exhibit excess extragalactic DM, some of which likely originate in the ICM of their respective clusters. FRB 20220914A resides in the galaxy cluster A2310 at z = 0.1125 with a projected offset from the cluster center of 520 ± 50 kpc. The host of a second source, FRB 20220509G, is an elliptical galaxy at z = 0.0894 that belongs to the galaxy cluster A2311 at the projected offset of 870 ± 50 kpc. These sources represent the first time an FRB has been localized to a galaxy cluster. We combine our FRB data with archival X-ray, Sunyaev-Zel'dovich (SZ), and optical observations of these clusters in order to infer properties of the ICM, including a measurement of gas temperature from DM and y SZ of 0.8-3.9 keV. We then compare our results to massive cluster halos from the IllustrisTNG simulation. Finally, we describe how large samples of localized FRBs from future surveys will constrain the ICM, particularly beyond the virial radius of clusters.

Keywords: Rich galaxy clusters, Radio bursts, Intracluster medium
JWST NIRSpec Observations of Supernova 1987A-From the Inner Ejecta to the Reverse Shock. We present initial results from JWST NIRSpec integral field unit observations of the nearby supernova SN 1987A. The observations provide the first spatially resolved spectroscopy of the ejecta and equatorial ring (ER) over the 1-5 μm range. We construct 3D emissivity maps of the [Fe I] 1.443 μm line from the inner ejecta and the He I 1.083 μm line from the reverse shock (RS), where the former probes the explosion geometry and the latter traces the structure of the circumstellar medium. We also present a model for the integrated spectrum of the ejecta. The [Fe I] 3D map reveals a highly asymmetric morphology resembling a broken dipole, dominated by two large clumps with velocities of ~2300 km s-1. We also find evidence that the Fe-rich inner ejecta have started to interact with the RS. The RS surface traced by the He I line extends from just inside the ER to higher latitudes on both sides of the ER with a half-opening angle ~45°, forming a bubble-like structure. The spectral model for the ejecta allows us to identify the many emission lines, including numerous H2 lines. We find that the H2 is most likely excited by far-UV emission, while the metal-line ratios are consistent with a combination of collisional excitation and recombination in the low-temperature ejecta. We also find several high-ionization coronal lines from the ER, requiring a temperature ≳2 × 106 K.

Keywords: Supernova remnants, Core-collapse supernovae
Wide-binary Stars Formed in the Turbulent Interstellar Medium. The ubiquitous interstellar turbulence regulates star formation and the scaling relations between the initial velocity differences and the initial separations of stars. We propose that the formation of wide binaries with initial separations r in the range ~103 au ≲ r ≲ 105 au is a natural consequence of star formation in the turbulent interstellar medium. With the decrease of r, the mean turbulent relative velocity v tur between a pair of stars decreases, while the largest velocity v bon at which they still may be gravitationally bound increases. When v tur &lt; v bon, a wide binary can form. In this formation scenario, we derive the eccentricity distribution p(e) of wide binaries for an arbitrary relative velocity distribution. By adopting a turbulent velocity distribution, we find that wide binaries at a given initial separation generally exhibit a superthermal p(e), irrespective of the exact turbulent velocity scaling. This provides a natural explanation for the observed superthermal p(e) of the wide binaries in the solar neighborhood.

Keywords: Gaia, Star formation, Interstellar medium, Wide binary stars
Mitigating Cosmic Microwave Background Shadow Degradation of Tensor-to-scalar Ratio Measurements through Map-based Studies. It has been pointed out that the spurious cosmic microwave background (CMB) B-mode polarization signals caused by the absorption of the CMB monopole component due to the Galactic interstellar matter, called the CMB shadow, degrade the accuracy of detecting the CMB B-mode polarization signals imprinted by primordial gravitational waves. We have made a realistic estimation using simulated sky maps of how the CMB shadow affects forthcoming high-precision CMB B-mode experiments for the first time. The delta-map method, an internal template method taking into account the first-order spatial variation of foregrounds' spectral parameters, is applied as a foreground-removal method. We show that if the CMB shadow effects are not taken into account in the foreground-removal process, future observations would lead to the false detection of the CMB B-mode polarization signals originating from primordial gravitational waves. We also show that the effect of the CMB shadow can be mitigated by our revised delta-map method to target the CMB B-mode polarization signals at the level of tensor-to-scalar ratio r = 0.001.

Keywords: Observational cosmology, Cosmic microwave background radiation, Interstellar dust extinction
The Decoupling of Binaries from Their Circumbinary Disks. We have investigated, both analytically and numerically, accreting supermassive black hole binaries as they inspiral due to gravitational radiation to elucidate the decoupling of binaries from their disks and inform future multimessenger observations of these systems. Our numerical studies evolve equal-mass binaries from initial separations of 100 GM/c until merger, resolving scales as small as ∼0.04 GM/c, where M is the total binary mass. Our simulations accurately capture the point at which the orbital evolution of each binary decouples from that of its circumbinary disk, and precisely resolve the flow of gas throughout the inspiral. We demonstrate analytically and numerically that timescale-based predictions overestimate the binary separations at which decoupling occurs by factors of ∼3, and illustrate the utility of a velocity-based decoupling criterion. High-viscosity (ν ≳ 0.03 GM/c) circumbinary systems decouple late (a  b  ≲ 15 GM/c) and have qualitatively similar morphologies near merger to circumbinary systems with constant binary separations. Lower-viscosity circumbinary disks decouple earlier and exhibit qualitatively different accretion flows, which lead to precipitously decreasing accretion onto the binary. If detected, such a decrease may unambiguously identify the host galaxy of an ongoing event within a LISA error volume. We illustrate how accretion amplitude and variability evolve as binaries gradually decouple from their circumbinary disks, and where decoupling occurs over the course of binary inspirals in the LISA band. We show that, even when dynamically negligible, gas may leave a detectable imprint on the phase of gravitational waves.

Keywords: Accretion, Hydrodynamical simulations, Active galactic nuclei, Gravitational wave astronomy
The Population of the Galactic Center Filaments: Position Angle Distribution Reveals a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane. We have examined the distribution of the position angle (PA) of the Galactic center filaments with lengths L &gt; 66″ and &lt;66″ as well as their length distribution as a function of PA. We find bimodal PA distributions of the filaments, and long and short populations of radio filaments. Our PA study shows the evidence for a distinct population of short filaments with PA close to the Galactic plane. Mainly thermal, short-radio filaments (&lt;66″) have PAs concentrated close to the Galactic plane within 60° &lt; PA &lt; 120°. Remarkably, the short filament PAs are radial with respect to the Galactic center at l &lt; 0° and extend in the direction toward Sgr A*. On a smaller scale, the prominent Sgr E H II complex G358.7-0.0 provides a vivid example of the nearly radial distribution of short filaments. The bimodal PA distribution suggests a different origin for two distinct filament populations. We argue that the alignment of the short-filament population results from the ram pressure of a degree-scale outflow from Sgr A* that exceeds the internal filament pressure, and aligns them along the Galactic plane. The ram pressure is estimated to be 2 × 106 cm-3 K at a distance of 300 pc, requiring biconical mass outflow rate 10-4 M ⊙ yr-1 with an opening angle of ~40°. This outflow aligns not only the magnetized filaments along the Galactic plane but also accelerates thermal material associated with embedded or partially embedded clouds. This places an estimate of ~6 Myr as the age of the outflow.

Keywords: Galactic center, Non-thermal radiation sources, Interstellar filaments
Magnetar Central Engines in Gamma-Ray Bursts Follow the Universal Relation of Accreting Magnetic Stars. Gamma-ray bursts (GRBs), both long and short, are explosive events whose inner engine is generally expected to be a black hole or a highly magnetic neutron star (magnetar) accreting high-density matter. Recognizing the nature of GRB central engines, and in particular the formation of neutron stars (NSs), is of high astrophysical significance. A possible signature of NSs in GRBs is the presence of a plateau in the early X-ray afterglow. Here we carefully select a subset of long and short GRBs with a clear plateau, and look for an additional NS signature in their prompt emission, namely a transition between the accretion and propeller phases in analogy with accreting, magnetic compact objects in other astrophysical sources. We estimate from the prompt emission the minimum accretion luminosity below which the propeller mechanism sets in, and the NS magnetic field and spin period from the plateau. We demonstrate that these three quantities obey the same universal relation in GRBs as in other accreting compact objects switching from accretion to propeller. This relation provides also an estimate of the radiative efficiency of GRBs, which we find to be several times lower than radiatively efficient accretion in X-ray binaries and in agreement with theoretical expectations. These results provide additional support to the idea that at least some GRBs are powered by magnetars surrounded by an accretion disk.

Keywords: Stellar accretion disks, Magnetars, Gamma-ray bursts, High energy astrophysics