Sazuna/UAT_keywords huggingface dataset:
The Discovery of Two LISA Sources within 0.5 kpc. We report the discovery of the brightest detached binary white dwarfs with periods less than an hour, which provide two new gravitational-wave verification binaries for the Laser Interferometer Space Antenna (LISA). The first one, SMSS J033816.16-813929.9 (hereafter J0338), is a 30.6 minute orbital period, g = 17.2 mag detached double white dwarf binary with a Gaia parallax measurement that places it at a distance of 533 pc. The observed radial velocity and photometric variability provide precise constraints on the system parameters. J0338 contains a 0.230 ± 0.015 M☉ white dwarf with a ${0.38}_{-0.03}^{+0.05}\,{M}_{\odot }$ companion at an inclination of 69° ± 9°. The second system, SDSS J063449.92+380352.2 (hereafter J0634), is a 26.5 minute orbital period, g = 17.0 mag detached double white dwarf binary at a distance of 435 pc. J0634 contains a ${0.452}_{-0.062}^{+0.070}\,{M}_{\odot }$ white dwarf with a ${0.209}_{-0.021}^{+0.034}\,{M}_{\odot }$ companion at an inclination of 37° ± 7°. The more massive white dwarf in J0634 is hotter than its companion, even though tidal dissipation is predicted to be relatively inefficient at such periods. This suggests that the more massive white dwarf formed last. J0338 and J0634 will be detected by LISA with a signal-to-noise ratio of 5 and 19, respectively, after four years. We identified these two systems based on their overluminosity and u-band photometry. Follow-up of u-band selected Gaia targets will likely yield additional LISA verification binaries.

Keywords: White dwarf stars, Compact binary stars, Gravitational waves, Gravitational wave sources
The Competing Effect of Gas and Stars in the Evolution of Massive Black Hole Binaries. Massive black hole binaries are predicted to form during the hierarchical assembly of cosmic structures and will represent the loudest sources of low-frequency gravitational waves (GWs) detectable by present and forthcoming GW experiments. Before entering the GW-driven regime, their evolution is driven by the interaction with the surrounding stars and gas. While stellar interactions are found to always shrink the binary, recent studies predict the possibility of binary outspiral mediated by the presence of a gaseous disk, which could endlessly delay the coalescence and impact the merger rates of massive binaries. Here we implement a semianalytical treatment that follows the binary evolution under the combined effect of stars and gas. We find that binaries may outspiral only if they accrete near or above their Eddington limit and only until their separation reaches the gaseous disk self-gravitating radius. Even in case of an outspiral, the binary eventually reaches a large enough mass for GW to take over and drive it to coalescence. The combined action of stellar hardening, mass growth, and GW-driven inspiral brings binaries to coalescence in a few hundreds of megayears at most, implying that gas-driven expansion will not severely affect the detection prospects of upcoming GW facilities.

Keywords: Supermassive black holes, Computational astronomy, Galaxy accretion disks, Stellar dynamics, Gravitational wave sources
The DUVET Survey: Direct T<SUB>e</SUB>-based Metallicity Mapping of Metal-enriched Outflows and Metal-poor Inflows in Markarian 1486. We present electron temperature (Te) maps for the edge-on system Mrk 1486, affording "direct-method" gas-phase metallicity measurements across 5"8 (4.1 kpc) along the minor axis and 9"9 (6.9 kpc) along the major axis. These maps, enabled by strong detections of the [O III] λ4363 auroral emission line across a large spatial extent of Mrk 1486, reveal a clear negative minor-axis Te gradient in which temperature decreases with increasing distance from the disk plane. We find that the lowest metallicity spaxels lie near the extremes of the major axis, while the highest metallicity spaxels lie at large spatial offsets along the minor axis. This is consistent with a picture in which low-metallicity inflows dilute the metallicity at the edges of the major axis of the disk, while star formation drives metal-enriched outflows along the minor axis. We find that the outflow metallicity in Mrk 1486 is 0.20 dex (1.6 times) higher than the average insterstellar medium (ISM) metallicity, and more than 0.80 dex (6.3 times) higher than metal-poor inflowing gas, which we observe to be below 5% Z⊙. This is the first example of metallicity measurements made simultaneously for inflowing, outflowing, and inner disk ISM gas using consistent Te-based methodology. These measurements provide unique insight into how baryon-cycle processes contribute to the assembly of a galaxy like Mrk 1486.

Keywords: Starburst galaxies, Interstellar medium, Emission line galaxies, Galaxies
Elemental Abundances of the Hot Atmosphere of Luminous Infrared Galaxy Arp 299. Hot atmospheres of massive galaxies are enriched with metals. Elemental abundances measured in the X-ray band have been used to study the chemical enrichment of supernova remnants, elliptical galaxies, groups, and clusters of galaxies. Here we measure the elemental abundances of the hot atmosphere of luminous infrared galaxy Arp 299 observed with XMM-Newton. To measure the abundances in the hot atmosphere, we use a multi-temperature thermal plasma model, which provides a better fit to the Reflection Grating Spectrometer data. The observed Fe/O abundance ratio is subsolar, while those of Ne/O and Mg/O are slightly above solar. Core-collapse supernovae (SNcc) are the dominant metal factory of elements like O, Ne, and Mg. We find some deviations between the observed abundance patterns and theoretical ones from a simple chemical enrichment model. One possible explanation is that massive stars with M⋆ ≳ 23-27 M☉ might not explode as SNcc and enrich the hot atmosphere. This is in accordance with the missing massive SNcc progenitors problem, where very massive progenitors M⋆ ≳ 18 M☉ of SNcc have not been clearly detected. It is also possible that theoretical SNcc nucleosynthesis yields of Mg/O yields are underestimated.

Keywords: X-ray astronomy, Starburst galaxies, High resolution spectroscopy, Core-collapse supernovae, Chemical abundances, Galaxy groups, Interacting galaxies
Radio, X-Ray, and Extreme-ultraviolet Observations of Weak Energy Releases in the "Quiet" Sun. We analyzed ground-based low frequency (&lt;100 MHz) radio spectral and imaging data of the solar corona obtained with the facilities in the Gauribidanur observatory during the same time as the very weak soft X-ray flares (sub-A-class, flux &lt;10-7Wm-2 in the 1-8 Å wavelength range) from the quiet Sun observed with the X-ray Solar Monitor (XSM) on board Chandrayaan-2 during the recent solar minimum. Nonthermal type I radio burst activity was noticed in close temporal association with the X-ray events. The estimated brightness temperature (Tb) of the bursts at a typical frequency like 80 MHz is ≈3 × 105 K. Extreme-ultraviolet (EUV) observations at 94 Å with the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) revealed a brightening close to the same location and time as the type I radio bursts. As far as we know reports of simultaneous observations of X-ray and/or EUV counterpart to weak transient radio emission at low frequencies from the quiet Sun in particular are rare. Considering this and the fact that low frequency radio observations are sensitive to weak energy releases in the solar atmosphere, the results indicate that coordinated observations of similar events would be useful to understand transient activities in the quiet Sun.

Keywords: Solar flares, Quiet sun, Solar radio emission, Solar corona, Solar x-ray flares, Solar activity
A Sample Bias in Quasar Variability Studies. When a flux-limited quasar sample is observed at later times, there will be more dimmed quasars than brightened ones, due to a selection bias induced at the time of sample selection. Quasars are continuously varying and there are more fainter quasars than brighter ones. At the time of selection, even symmetrical variability will result in more quasars with their instantaneous fluxes scattered above the flux limit than those scattered below, leading to an asymmetry in flux changes over time. The same bias would lead to an asymmetry in the ensemble structure function (SF) of the sample such that the SF based on pairs with increasing fluxes will be slightly smaller than that based on pairs with decreasing fluxes. We use simulated time-symmetric quasar light curves based on the damped random walk prescription to illustrate the effects of this bias. The level of this bias depends on the sample, the threshold of magnitude changes, and the coverage of light curves, but the general behaviors are consistent. In particular, the simulations matched to recent observational studies with decade-long light curves produce an asymmetry in the SF measurements at the few percent level, similar to the observed values. These results provide a cautionary note on the reported time asymmetry in some recent quasar variability studies.

Keywords: Surveys, Black hole physics, Quasars
Coronal Microjets in Quiet-Sun Regions Observed with the Extreme Ultraviolet Imager on Board the Solar Orbiter. We report the smallest coronal jets ever observed in the quiet Sun with recent high-resolution observations from the High Resolution Telescopes (HRIEUV and HRILyα) of the Extreme Ultraviolet Imager on board the Solar Orbiter (SO). In the HRIEUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 minutes, 62 km s-1, 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also reveal signatures in the HRILyα (H I Lyα at 1216 Å) images and the extreme ultraviolet images taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Our differential emission-measure (EM) analysis suggests a multithermal nature and an average density of ~1.4 × 109 cm-3 for these microjets. Their thermal and kinetic energies were estimated to be ~3.9 × 1024 erg and ~2.9 × 1023 erg, respectively, which are of the same order of the released energy predicted by the nanoflare theory. Most events appear to be located at the edges of network lanes and magnetic flux concentrations, suggesting that these coronal microjets are likely generated by magnetic reconnection between small-scale magnetic loops and the adjacent network field.

Keywords: Solar corona, Quiet sun, Solar ultraviolet emission
Resonant Tidal Responses in Rotating Fluid Bodies: Global Modes Hidden beneath Localized Wave Beams. In rotating stars and planets, excitation of inertial waves in convective envelopes provides an important channel for tidal dissipation, but the dissipation rate due to inertial waves depends erratically on the tidal frequency. Tidal dissipation is significantly enhanced at some frequencies, suggesting possible resonances between the tidal forcing and some eigenmodes. However, the nature of these resonances remains enigmatic owing to the singularity of the eigenvalue problem of inertial waves, and the resonances are often mistakenly attributed to wave attractors in the literature. In this Letter, we reveal that resonant tidal responses correspond to inertial modes with large-scale flows hidden beneath localized wave beams. Strong couplings between the tidal forcing and the hidden large-scale flows intensify the localized wave beams emanating from the critical latitudes, leading to enhanced tidal dissipation. This study resolves a longstanding puzzle regarding the frequency dependence of tidal dissipation due to inertial waves in convective envelopes.

Keywords: Tidal interaction, Internal waves
Can the Blandford-Znajek Mechanism Power Steady Jets?. We consider the Blandford-Znajek (BZ) mechanism for extracting black hole spin energy to drive astrophysical jets. Analyses of the BZ mechanism generally take no account of any electric charge on the black hole. But, as noted by Wald and others, if the medium surrounding the black hole is an ionized plasma with mobile charges, then a spinning hole quickly acquires an electric charge. The effect of this charge is to nullify the electric field structures which drive the BZ mechanism. Since jets are now observed in a wide variety of classes of accreting objects, most of which do not contain a central black hole, it seems likely that the jet-driving mechanism in all astrophysical objects uses energy directly from the accretion disk, rather than black hole spin.

Keywords: Accretion, Black hole physics, Radio jets
The Nature and Composition of Jupiter's Building Blocks Derived from the Water Abundance Measurements by the Juno Spacecraft. The microwave radiometer on board the Juno spacecraft provided a measurement of the water abundance found to range between ~1 and 5.1 times the protosolar abundance of oxygen in the near-equatorial region of Jupiter. Here, we aim to combine this up-to-date oxygen determination, which is likely to be more representative of the bulk abundance than the Galileo probe subsolar value, with the other known measurements of elemental abundances in Jupiter, to derive the formation conditions and initial composition of the building blocks agglomerated by the growing planet, and that determine the heavy element composition of its envelope. We investigate several cases of formation of icy solids in the protosolar nebula (PSN), from the condensation of pure ices to the crystallization of mixtures of pure condensates and clathrates in various proportions. Each of these cases corresponds to a distinct solid composition whose amount is adjusted in the envelope of Jupiter to match the O abundance measured by Juno. The volatile enrichments can be matched by a wide range of planetesimal compositions, from solids exclusively formed from pure condensates or from nearly exclusively clathrates, the latter case providing a slightly better fit. The total mass of volatiles needed in the envelope of Jupiter to match the observed enrichments is within the ~4.3-39 M⊕ range, depending on the crystallization scenario considered in the PSN. A wide range of masses of heavy elements derived from our fits is found to be compatible with the envelope's metallicity calculated from current interior models.

Keywords: Solar system formation, Solar system gas giant planets, Jupiter, Protoplanetary disks, Planetesimals, Planet formation
Formation of Multiple Populations of M5 (NGC 5904). With our new Ca-CN-CH-NH photometry, we revisit the globular cluster (GC) M5. We find that M5 is a mono-metallic GC with a small metallicity dispersion. Our carbon abundances show that the σ[C/Fe] of the M5 CN-s population, with depleted carbon and enhanced nitrogen abundances, is significantly large for a single stellar population. Our new analysis reveals that the M5 CN-s population is well described by the two stellar populations: the CN-sI, being the major CN-s component, with the intermediate carbon and nitrogen abundance and the CN-sE with the most carbon-poor and nitrogen-rich abundance. We find that the CN-sE is significantly more centrally concentrated than the others, while CN-w and CN-sI have similar cumulative radial distributions. The red giant branch bump V magnitude, the helium abundance barometer in mono-metallic populations, of individual populations appears to be correlated with their mean carbon abundance, indicating that carbon abundances are anticorrelated with helium abundances. We propose that the CN-sE formed out of gas that experienced proton-capture processes at high temperatures in the innermost region of the proto-GC of M5 that resided in a dense ambient density environment. Shortly after, the CN-sI formed out of gas diluted from the pristine gas in the more spatially extended region, consistent with the current development of numerical simulations by others.

Keywords: Globular star clusters, Hertzsprung Russell diagram, Red giant branch, Stellar populations, Population II stars, Stellar evolution
On the Detection of Exomoons Transiting Isolated Planetary-mass Objects. All-sky imaging surveys have identified several dozen isolated planetary-mass objects (IPMOs) far away from any star. Here we examine the prospects for detecting transiting moons around these objects. We expect transiting moons to be common, occurring around 10%-15% of IPMOs, given that close-orbiting moons have a high geometric transit probability and are expected to be a common outcome of giant planet formation. The IPMOs offer an advantage over other directly imaged planets in that high-contrast imaging is not necessary to detect the photometric transit signal. For at least 30 (&gt;50%) of the currently known IPMOs, observations of a single transit with the James Webb Space Telescope would have low enough forecast noise levels to allow for the detection of an Io- or Titan-like moon. The intrinsic variability of the IPMOs will be an obstacle. Using archival time-series photometry of IPMOs with the Spitzer Space Telescope as a proof of concept, we found evidence for a fading event of 2MASS J1119-1137 AB that might have been caused by intrinsic variability but is also consistent with a single transit of a habitable-zone 1.7 R⊕ exomoon. Although the interpretation of this particular event is inconclusive, the characteristics of the data and the candidate signal suggest that Earth-sized habitable-zone exomoons around IPMOs are detectable with existing instrumentation.

Keywords: Natural satellites (Extrasolar), Transits, Exoplanets, Free floating planets, Habitable zone
NICER Detection of Thermal X-Ray Pulsations from the Massive Millisecond Pulsars PSR J0740+6620 and PSR J1614-2230. We report the detection of X-ray pulsations from the rotation-powered millisecond-period pulsars PSR J0740+6620 and PSR J1614-2230, two of the most massive neutron stars known, using observations with the Neutron Star Interior Composition Explorer (NICER). We also analyze X-ray Multi-Mirror Mission (XMM-Newton) data for both pulsars to obtain their time-averaged fluxes and study their respective X-ray fields. PSR J0740+6620 exhibits a broad double-peaked profile with a separation of ~0.4 in phase. PSR J1614-2230, on the other hand, has a broad single-peak profile. We show the NICER detections of X-ray pulsations for both pulsars and also discuss the phase relationship to their radio pulsations. The XMM-Newton X-ray spectra of both pulsars shows they are thermally dominated but in the case of PSR J1614-2230 a weak nonthermal high energy tail appears to be present in the spectrum. The thermally dominated spectra along with broad modulations for both pulsars are indicative of thermal radiation from one or more small regions of the stellar surface. For PSR J0740+6620, this paper documents the data reduction performed to obtain the pulsation detection and prepare for pulse light curve modeling analysis.

Keywords: Neutron stars, X-ray binary stars, Rotation powered pulsars, Millisecond pulsars
A NICER View of the Massive Pulsar PSR J0740+6620 Informed by Radio Timing and XMM-Newton Spectroscopy. We report on Bayesian estimation of the radius, mass, and hot surface regions of the massive millisecond pulsar PSR J0740+6620, conditional on pulse-profile modeling of Neutron Star Interior Composition Explorer X-ray Timing Instrument event data. We condition on informative pulsar mass, distance, and orbital inclination priors derived from the joint North American Nanohertz Observatory for Gravitational Waves and Canadian Hydrogen Intensity Mapping Experiment/Pulsar wideband radio timing measurements of Fonseca et al. We use XMM-Newton European Photon Imaging Camera spectroscopic event data to inform our X-ray likelihood function. The prior support of the pulsar radius is truncated at 16 km to ensure coverage of current dense matter models. We assume conservative priors on instrument calibration uncertainty. We constrain the equatorial radius and mass of PSR J0740+6620 to be ${12.39}_{-0.98}^{+1.30}$ km and ${2.072}_{-0.066}^{+0.067}$ M☉ respectively, each reported as the posterior credible interval bounded by the 16% and 84% quantiles, conditional on surface hot regions that are non-overlapping spherical caps of fully ionized hydrogen atmosphere with uniform effective temperature; a posteriori, the temperature is ${\mathrm{log}}_{10}(T\,[{\rm{K}}])={5.99}_{-0.06}^{+0.05}$ for each hot region. All software for the X-ray modeling framework is open-source and all data, model, and sample information is publicly available, including analysis notebooks and model modules in the Python language. Our marginal likelihood function of mass and equatorial radius is proportional to the marginal joint posterior density of those parameters (within the prior support) and can thus be computed from the posterior samples.

Keywords: X-ray astronomy, Neutron stars, Rotation powered pulsars, Millisecond pulsars, Pulsars, Radio pulsars
The Radius of PSR J0740+6620 from NICER and XMM-Newton Data. PSR J0740+6620 has a gravitational mass of 2.08 ± 0.07 M☉, which is the highest reliably determined mass of any neutron star. As a result, a measurement of its radius will provide unique insight into the properties of neutron star core matter at high densities. Here we report a radius measurement based on fits of rotating hot spot patterns to Neutron Star Interior Composition Explorer (NICER) and X-ray Multi-Mirror (XMM-Newton) X-ray observations. We find that the equatorial circumferential radius of PSR J0740+6620 is ${13.7}_{-1.5}^{+2.6}$ km (68%). We apply our measurement, combined with the previous NICER mass and radius measurement of PSR J0030+0451, the masses of two other ~2 M☉ pulsars, and the tidal deformability constraints from two gravitational wave events, to three different frameworks for equation-of-state modeling, and find consistent results at ~1.5-5 times nuclear saturation density. For a given framework, when all measurements are included, the radius of a 1.4 M☉ neutron star is known to ±4% (68% credibility) and the radius of a 2.08 M☉ neutron star is known to ±5%. The full radius range that spans the ±1σ credible intervals of all the radius estimates in the three frameworks is 12.45 ± 0.65 km for a 1.4 M☉ neutron star and 12.35 ± 0.75 km for a 2.08 M☉ neutron star.

Keywords: Neutron stars, Neutron star cores, X-ray sources, Millisecond pulsars