adsabs/SciX_UAT_keywords huggingface dataset:
Gravitational-wave Constraints on the Cosmic Opacity at z ∼ 5: Forecast from Space Gravitational-wave Antenna DECIGO

Since gravitational waves (GWs) propagate freely through a perfect fluid, coalescing compact binary systems as standard sirens allow us to measure the luminosity distance directly and provide distance measurements unaffected by the cosmic opacity. DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO) is a future Japanese space gravitational-wave antenna sensitive to frequency range between target frequencies of the Laser Interferometric Space Antenna and ground-based detectors. Combining the predicted future GW observations from DECIGO and three current popular astrophysical probes (H II regions, SNe Ia Pantheon sample, quasar sample) in electromagnetic domains, one would be able to probe the opacity of the universe at different redshifts. In this paper, we show that the cosmic-opacity parameter can be constrained to a high precision (Δɛ ∼ 10-2) out to high redshifts (z ∼ 5). In order to reconstruct the evolution of cosmic opacity without assuming any particular functional form of it, the cosmic-opacity tests should be applied to individual redshift bins independently. Therefore, we also calculate the optical depth at individual redshifts and averaged τ(z) within redshift bins. Our findings indicate that, compared with the results obtained from the H II galaxies and Pantheon SNe Ia, there is an improvement in precision when the quasar sample is considered. While nonzero optical depth is statistically significant only for redshift ranges 0 < z < 0.5, 1 < z < 2, and 2.5 < z < 3.5, such a tendency is different from that obtained in the framework of its parameterized form. Therefore, the importance of a cosmic-opacity test without a prescribed phenomenological function should be emphasized.

Keywords: cosmological parameters; gravitational wave detectors; gravitational waves
Mid-infrared Polarization of the Diffuse Interstellar Medium toward CygOB2-12

We present the first mid-IR detection of the linear polarization toward the star CygOB2-12, a luminous blue hypergiant that, with A V ≈ 10 mag of foreground extinction, is a benchmark in the study of the properties of dust in the diffuse interstellar medium. The 8-13 μm spectropolarimetry, obtained with the CanariCam multimode camera at the Gran Telescopio CANARIAS shows clear trends with wavelength characteristic of silicate grains aligned in the interstellar magnetic field. The maximum polarization, detected with 7.8σ statistical significance near 10.2 μm, is (1.24 ± 0.28)% with position angle 126° ± 8°. We comment on these measurements in the context of recent models for the dust composition in the diffuse interstellar medium.

Keywords: diffuse interstellar clouds; spectropolarimetry; silicate grains
Implications of NICER for Neutron Star Matter: The QHC21 Equation of State

The recent NICER measurement of the radius of the neutron star PSR J0740+6620, and the inferred small variation of radii from 1.4 to 2.1 M ⊙, reveal key features of the equation of state of neutron star matter. The pressure rises rapidly in the regime of baryon density n ~ 2-4 times nuclear saturation density, n 0-the region where we expect hadronic matter to be undergoing transformation into quark matter-and the pressure in the nuclear regime is greater than predicted by microscopic many-body variational calculations of nuclear matter. To incorporate these insights into the microscopic physics from the nuclear to the quark matter regimes, we construct an equation of state, QHC21, within the framework of quark-hadron crossover. We include nuclear matter results primarily based on the state-of-the-art chiral effective field theory, but also note results of using nuclear matter variational calculations based on empirical nuclear forces. We employ explicit nuclear degrees of freedom only up to n ~ 1.5 n 0, in order to explore the possibility of further physical degrees of freedom than nucleonic here. The resulting QHC21, which has a peak in sound velocity in ~2-4 n 0, is stiffer than the earlier QHC19 below 2 n 0, predicting larger radii in substantial agreement with the NICER data.

Keywords: neutron star cores
Universal Upper End of the Stellar Initial Mass Function in the Young and Compact LEGUS Clusters

We investigate the variation in the upper end of the stellar initial mass function (uIMF) in 375 young and compact star clusters in five nearby galaxies within ~5 Mpc. All the young stellar clusters (YSCs) in the sample have ages ≲ 4 Myr and masses above 500 M ⊙, according to standard stellar models. The YSC catalogs were produced from Hubble Space Telescope images obtained as part of the Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. They are used here to test whether the uIMF is universal or changes as a function of the cluster's stellar mass. We perform this test by measuring the Hα luminosity of the star clusters as a proxy for their ionizing photon rate, and charting its trend as a function of cluster mass. Large cluster numbers allow us to mitigate the stochastic sampling of the uIMF. The advantage of our approach relative to previous similar attempts is the use of cluster catalogs that have been selected independently of the presence of Hα emission, thus removing a potential sample bias. We find that the uIMF, as traced by the Hα emission, shows no dependence on cluster mass, suggesting that the maximum stellar mass that can be produced in star clusters is universal, in agreement with previous findings.

Keywords: star clusters; young star clusters; massive stars; ob stars; star formation; initial mass function; interstellar line emission
Quark Stars in 4D Einstein-Gauss-Bonnet Gravity with an Interacting Quark Equation of State

The detection of gravitational waves (GWs) from a binary neutron star (BNS) has opened a new window on gravitational wave astronomy. With current sensitivities, detectable signals coming from compact objects like neutron stars turn out to be a crucial ingredient for probing their structure, composition, and evolution. Moreover, astronomical observations on pulsars and their mass-radius relations place important constraints on the dense matter equation of state. In this paper, we consider a homogeneous and unpaired charge-neutral three-flavor interacting quark matter with ${ \mathcal O }({m}_{s}^{4})$ corrections that account for the moderately heavy strange quark instead of the naive MIT bag model. We perform a detailed analysis of strange quark stars in the context of the recently proposed 4D Einstein-Gauss-Bonnet (EGB) theory of gravity. However, this theory does not have standard 4D equations. Thus, we show that the equivalence of the actions in the regularized 4D EGB theory and in the original one is satisfied for a spherically symmetric spacetime. We pay particular attention to the possible existence of neutron stars of mass compatible with $M\sim 2{M}_{\odot }$ . Our findings suggest that the fourth-order correction parameter (a4) of the quantum chromodynamic perturbation and coupling constant α of the GB term play an important role in the mass-radius relation as well as the stability of the quark star. Finally, we compare the results with the well-measured limits of pulsars and their mass and radius extracted from the spectra of several X-ray compact sources.

Keywords: neutron stars; compact objects
Kelvin-Helmholtz Instability at Mars: In Situ Observations and Kinetic Simulations

Kelvin-Helmholtz (K-H) instability is a fundamental boundary instability between two fluids with different speeds, exchanging the mass, momentum, and energy across the boundary. Although the K-H instability has been suggested to play a critical role in atmospheric ion loss on Mars, the knowledge about its formation and evolution is still poor, due to the limitation of spacecraft missions and a dearth of dedicated simulation codes. In this study, we combine observations from the Mars Atmosphere and Volatile EvolutioN mission and global 3D kinetic simulations to investigate the solar wind-Mars interaction. For the first time, it is found that K-H waves prominently appear in the -E hemisphere, which is attributed to the stronger proton velocity shear therein associated with the asymmetric diamagnetic drift motion of protons. The K-H instability is mainly excited in the -E hemisphere and propagates downstream along the boundary, with the waves also able to be generated near the subsolar point. The K-H waves produce plasma clouds with a net oxygen ion escape rate of about 1.5 × 1024 s-1, contributing to almost half of the global loss on present-day Mars. This heavy ion escape pattern associated with K-H instability is cyclic and could occur on other nonmagnetized planets, potentially influencing planetary atmosphere evolution and habitability.

Keywords: mars; planetary boundary layers; solar-planetary interactions; space plasmas
Toward Early-type Eclipsing Binaries as Extragalactic Milestones. III. Physical Properties of the O-type Eclipsing Binary OGLE LMC-ECL-21568 in a Quadruple System

We present the results from a complex study of an eclipsing O-type binary (Aa+Ab) with the orbital period of P A = 3.2254367 days that forms part of a higher-order multiple system in a configuration of (A+B)+C. We derived masses of the Aa+Ab binary of M 1 = 19.02 ± 0.12 and M 2 = 17.50 ± 0.13 M ⊙, the radii of R 1 = 7.70 ± 0.05 and R 2 = 6.64 ± 0.06 R ⊙, and temperatures of T 1 = 34,250 ± 500 K and T 2 = 33,750 ± 500 K. From the analysis of the radial velocities, we found a spectroscopic orbit of A in the outer A+B system with P A+B = 195.8 days (P A+B/P A ≈ 61). In the O ‑ C analysis, we confirmed this orbit and found another component orbiting the A+B system with P AB+C = 2550 days (P AB+C/P A+B ≈ 13). From the total mass of the inner binary and its outer orbit, we estimated the mass of the third object, M B ≳ 10.7 M ⊙. From the light travel time effect fit to the O ‑ C data, we obtained the limit for the mass of the fourth component, M C ≳ 7.3 M ⊙. These extra components contribute about 20%–30% (increasing with wavelength) to the total system light. From the comparison of model spectra with the multiband photometry, we derived a distance modulus of 18.59 ± 0.06 mag, a reddening of 0.16 ± 0.02 mag, and an RV of 3.2. This work is part of our ongoing project, which aims to calibrate the surface brightness–color relation for early-type stars. *Based on observations collected at the European Southern Observatory, Chile. † This paper includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

Keywords: detached binary stars; multiple stars; large magellanic cloud; early-type stars; o stars; eclipsing binary stars
shock_cooling_curve: A Python-based Package for Extensive and Efficient Modeling of Shock Cooling Emission in Supernovae

The light-curve evolution of a supernova contains information on the exploding star. Early-time photometry of a variety of explosive transients, including Calcium-rich transients and type IIb/Ibc and IIP supernovae shows evidence for an early light curve peak as a result of the explosion's shock wave passing through extended material (i.e., shock cooling emission (SCE)). Analytic modeling of the SCE allows us to estimate progenitor properties such as the radius and mass of extended material (e.g., the stellar envelope) as well as the shock velocity. In this work, we present a Python-based open-source code that implements four analytic models originally developed in Piro, Piro et al. and Sapir & Waxman applied to photometric data to obtain progenitor parameter properties via different modeling techniques (including nonlinear optimization, Markov Chain Monte Carlo sampling). Our software is easily extendable to other analytic models for SCE and different methods of parameter estimation.

Keywords: supernovae; shocks; open source software
Multiband Emission Properties of 1ES 1959+650

We have systemically studied the properties of 1ES 1959+650, specifically its multiband variability and emission mechanisms. We carefully analyze multiband variability properties by four different kinds of trusted approaches. In contrast with previous research and thanks to our more detailed data, we find that an unprecedented significant quasi-periodic component with timescale $P={266.2}_{-7.2}^{+7.5}$ in the optical R band indeed exists. We suggest that this light curve may result from accretion flow instabilities. Further, among the multiband spectra, we find no significant correlation between different bands, which implies that the physical origin of the dominant radiation for different bands is not the same. Motivated by these results, we go on further to study the radiation mechanisms based on quasi-simultaneous spectra. Here, a model that self-consistently involves protons, electrons, and photons is used to study the light curve and interpret the spectral energy distribution of 1ES 1959+650. Considering the variability properties and model calculation, we suggest that the variation of the cutoff energy of electrons and protons may dominate the variability of X-ray and γ-ray bands in 1ES 1959+650.

Keywords: active galaxies; bl lacertae objects; non-thermal radiation sources
The Common Envelope Evolution Outcome. II. Short-orbital-period Hot Subdwarf B Binaries Reveal a Clear Picture

Common envelope evolution (CEE) is vital for forming short-orbital-period compact binaries. It covers many objects, such as double compact merging binaries, Type Ia supernovae progenitors, binary pulsars, and X-ray binaries. Knowledge of the common envelope (CE) ejection efficiency still needs to be improved, though progress has been made recently. Short-orbital-period hot subdwarf B star (sdB) plus white dwarf (WD) binaries are the most straightforward samples with which to constrain CEE physics. We apply the known orbital period–WD mass relation to constrain the sdB progenitors of seven sdB+WD binaries with a known inclination angle. The average CE efficiency parameter is 0.32. This is consistent with previous studies. However, the CE efficiency need not be constant, but a function of the initial mass ratio, based on well-constrained sdB progenitor mass and evolutionary stage. Our results can be used as physical inputs for binary population synthesis simulations of related objects. A similar method can also be applied to study other short-orbital-period WD binaries.

Keywords: binary stars; b subdwarf stars; stellar physics; common envelope evolution
Paβ, Hα, and Attenuation in NGC 5194 and NGC 6946

We combine Hubble Space Telescope Paschen β (Paβ) imaging with ground-based, previously published Hα maps to estimate the attenuation affecting Hα, A(Hα), across the nearby, face-on galaxies NGC 5194 and NGC 6946. We estimate A(Hα) in ∼2000 independent 2″ ∼ 75 pc diameter apertures in each galaxy, spanning out to a galactocentric radius of almost 10 kpc. In both galaxies, A(Hα) drops with radius, with a bright, high-attenuation inner region, though in detail the profiles differ between the two galaxies. Regions with the highest attenuation-corrected Hα luminosity show the highest attenuation, but the observed Hα luminosity of a region is not a good predictor of attenuation in our data. Consistent with much previous work, the IR-to-Hα color does a good job of predicting A(Hα). We calculate the best-fit empirical coefficients for use combining Hα with 8, 12, 24, 70, or 100 μm to correct for attenuation. These agree well with previous work, but we also measure significant scatter around each of these linear relations. The local atomic plus molecular gas column density, N(H), also predicts A(Hα) well. We show that a screen with magnitude ∼0.2 times that expected for a Milky Way gas-to-dust value does a reasonable job of explaining A(Hα) as a function of N(H). This could be expected if only ∼40% of gas and dust directly overlap regions of Hα emission.

Keywords: galaxies; interstellar dust extinction; star formation
Multiple Regions of Nonthermal Quasiperiodic Pulsations during the Impulsive Phase of a Solar Flare

Flare-associated quasiperiodic pulsations (QPPs) in radio and X-ray wavelengths, particularly those related to nonthermal electrons, contain important information about the energy release and transport processes during flares. However, the paucity of spatially resolved observations of such QPPs with a fast time cadence has been an obstacle for us to further understand their physical nature. Here, we report observations of such a QPP event that occurred during the impulsive phase of a C1.8-class eruptive solar flare using radio imaging spectroscopy data from the Karl G. Jansky Very Large Array (VLA) and complementary X-ray imaging and spectroscopy data. The radio QPPs, observed by the VLA in the 1-2 GHz with a subsecond cadence, are shown as three spatially distinct sources with different physical characteristics. Two radio sources are located near the conjugate footpoints of the erupting magnetic flux rope with opposite senses of polarization. One of the sources displays a QPP behavior with a ~5 s period. The third radio source, located at the top of the postflare arcade, coincides with the location of an X-ray source and shares a similar period of ~25-45 s. We show that the two oppositely polarized radio sources are likely due to coherent electron cyclotron maser emission. On the other hand, the looptop QPP source, observed in both radio and X-rays, is consistent with incoherent gyrosynchrotron and bremsstrahlung emission, respectively. We conclude that the concurrent, but spatially distinct QPP sources must involve multiple mechanisms which operate in different magnetic loop systems and at different periods.

Keywords: solar flares; solar radio emission; solar oscillations; solar radio flares; solar x-ray flares
Extreme Variability and Episodic Lifetime of Quasars

We constrain the average episodic quasar lifetime (as in steady-state accretion) using two statistics of quasars that are recently turned off (i.e., dimmed by a large factor): (1) the fraction of turned-off quasars in a statistical sample photometrically observed over an extended period (e.g., Δt = 20 yr) and (2) the fraction of massive galaxies that show "orphan" broad Mg II emission, argued to be short-lived echoes of recently turned-off quasars. The two statistics constrain the average episodic quasar lifetime to be hundreds to thousands of years. Much longer (or shorter) episodic lifetimes are strongly disfavored by these observations. This average episodic lifetime is broadly consistent with the infall timescale (viscous time) in the standard accretion-disk model for quasars, suggesting that quasar episodes are governed by accretion-disk physics rather than by the gas supply on much larger scales. Compared with the cumulative quasar lifetime of ~106-108 yr constrained from quasar clustering and massive black hole demographics, our results suggest that there are ~103-105 episodes of quasar accretion during the assembly history of the supermassive black hole. Such short episodes should be clustered over intervals of ~104 yr to account for the sizes of ionized narrow-line regions in quasars. Our statistical argument also dictates that there will always be a small fraction of extreme variability quasars caught in "state transitions" over multiyear observing windows, despite the much longer episodic lifetime. These transitions could occur in a rather abrupt fashion during non-steady accretion.

Keywords: quasars; active galactic nuclei; surveys
An Atypical Low-frequency Quasiperiodic Oscillation Detected in the Hard State of MAXI J1348–630 with Insight-HXMT

Based on the Insight-HXMT archival data, we have detected a new atypical low-frequency quasiperiodic oscillation (LFQPO) in the black hole X-ray binary MAXI J1348‑630. The new LFQPO is detected in all three instruments of Insight-HXMT with a combined significance of 3σ–5σ, covering a wide energy range of 1–100 keV. The fractional rms seems to decrease with energy. It exclusively appears in the hard state during both the main and mini outburst, spanning an X-ray intensity range by a factor of 10, and a very narrow hardness range. The frequency of this new type of LFQPO is moderately stable, in the range of 0.08–0.15 Hz. We discussed different models for the LFQPO, and found none can explain the observed properties of this new type of LFQPO.

Keywords: x-ray binary stars; stellar accretion disks
On Trapped Modes in Variable White Dwarfs as Probes of the 12C(α, γ)16O Reaction Rate

We seek signatures of the current experimental 12C ${\left(\alpha ,\gamma \right)}^{16}{\rm{O}}$ reaction rate probability distribution function in the pulsation periods of carbon-oxygen white dwarf (WD) models. We find that adiabatic g-modes trapped by the interior carbon-rich layer offer potentially useful signatures of this reaction rate probability distribution function. Probing the carbon-rich region is relevant because it forms during the evolution of low-mass stars under radiative helium-burning conditions, mitigating the impact of convective mixing processes. We make direct quantitative connections between the pulsation periods of the identified trapped g-modes in variable WD models and the current experimental 12C ${\left(\alpha ,\gamma \right)}^{16}{\rm{O}}$ reaction rate probability distribution function. We find an average spread in relative period shifts of ΔP/P ≃ ±2% for the identified trapped g-modes over the ±3σ uncertainty in the 12C ${\left(\alpha ,\gamma \right)}^{16}{\rm{O}}$ reaction rate probability distribution function-across the effective temperature range of observed DAV and DBV WDs and for different WD masses, helium shell masses, and hydrogen shell masses. The g-mode pulsation periods of observed WDs are typically given to six to seven significant figures of precision. This suggests that an astrophysical constraint on the 12C ${\left(\alpha ,\gamma \right)}^{16}{\rm{O}}$ reaction rate could, in principle, be extractable from the period spectrum of observed variable WDs.

Keywords: white dwarf stars; asteroseismology; stellar physics; nuclear astrophysics
A Black Hole Kicked at Birth: MAXI J1305-704

When a compact object is formed in a binary, any mass lost during core collapse will impart a kick on the binary's center of mass. Asymmetries in this mass loss or neutrino emission would impart an additional natal kick on the remnant black hole or neutron star, whether it was formed in a binary or in isolation. While it is well established that neutron stars receive natal kicks upon formation, it is unclear whether black holes do as well. Here, we consider the low-mass X-ray binary MAXI J1305-704, which has been reported to have a space velocity ≳200 km s-1. In addition to integrating its trajectory to infer its velocity upon formation of its black hole, we account for recent estimates of its period, black hole mass, mass ratio, and donor effective temperature from photometric and spectroscopic observations. We find that if MAXI J1305-704 formed via isolated binary evolution in the thick Galactic disk, then the supernova that formed its black hole imparted a natal kick of at least 70 km s-1 while ejecting less than ≃1 M ⊙ with 95% confidence assuming uninformative priors on mass loss and natal kick velocity.

Keywords: astrophysical black holes; low-mass x-ray binary stars; supernovae