Sazuna/UAT_keywords huggingface dataset:
Cosmology with Galaxy Cluster Weak Lensing: Statistical Limits and Experimental Design. We forecast constraints on the amplitude of matter clustering σ8(z) achievable with the combination of cluster weak lensing and number counts, in current and next-generation weak lensing surveys. We advocate for an approach, analogous to galaxy-galaxy lensing, in which the observables in each redshift bin are the mean number counts and the mean weak lensing profile of clusters above a mass proxy threshold. The primary astrophysical nuisance parameter is the logarithmic scatter ${\sigma }_{\mathrm{ln}M}$ between the mass proxy and true mass near the threshold. For surveys similar to the Dark Energy Survey (DES), the Roman Space Telescope High Latitude Survey (HLS), and the Rubin Observatory Legacy Survey of Space and Time (LSST), we forecast aggregate precision on σ8 of 0.26%, 0.24%, and 0.10%, respectively, if the mass-observable scatter is known externally to ${\rm{\Delta }}{\sigma }_{\mathrm{ln}M}\leqslant 0.01$ . These constraints would be degraded by about 20% for ${\rm{\Delta }}{\sigma }_{\mathrm{ln}M}=0.05$ in the case of DES or HLS and for ${\rm{\Delta }}{\sigma }_{\mathrm{ln}M}=0.016$ for LSST. A 1 month observing program with Roman Space Telescope targeting ∼2500 massive clusters could achieve a ∼ 0.5% constraint on σ8(z = 0.7) on its own, or a ∼ 0.33% constraint in combination with the HLS. Realizing the constraining power of clusters Requires accurate knowledge of the mass-observable relation and stringent control of systematics. We provide analytic approximations to our numerical results that allow for easy scaling to other survey assumptions or other methods of cluster mass estimation.

Keywords: Galaxy clusters, Cosmology, Weak gravitational lensing, Sigma8, Cosmological parameters
Toward Cosmological Simulations of Dark Matter on Quantum Computers. State-of-the-art cosmological simulations on classical computers are limited by time, energy, and memory usage. Quantum computers can perform some calculations exponentially faster than classical computers, using exponentially less energy and memory, and may enable extremely large simulations that accurately capture the whole dynamic range of structure in the universe within statistically representative cosmic volumes. However, not all computational tasks exhibit a "quantum advantage." Quantum circuits act linearly on quantum states, so nonlinearities (e.g., self-gravity in cosmological simulations) pose a significant challenge. Here we outline one potential approach to overcome this challenge and solve the (nonlinear) Schrödinger-Poisson equations for the evolution of self-gravitating dark matter, based on a hybrid quantum-classical variational algorithm framework (Lubasch et al.). We demonstrate the method with a proof-of-concept mock quantum simulation, envisioning a future where quantum computers will one day lead simulations of dark matter.

Keywords: Gravitation, Computational methods, Dark matter
Merger Rate Density of Population III Binary Black Holes Below, Above, and in the Pair-instability Mass Gap. We present the merger rate density of Population III binary black holes (BHs) by means of a widely used binary population synthesis code BSE with extensions to very massive and extreme metal-poor stars. We consider not only low-mass BHs (lBHs: 5-50M⊙) but also high-mass BHs (hBHs: 130-200M⊙), where lBHs and hBHs are below and above the pair-instability mass gap (50-130M⊙), respectively. Population III BH-BHs can be categorized into three subpopulations: BH-BHs without hBHs (hBH0s: mtot ≲ 100M⊙), with one hBH (hBH1s: mtot ∼ 130-260M⊙), and with two hBHs (hBH2s: mtot ∼ 270-400M⊙), where mtot is the total mass of a BH-BH. Their merger rate densities at the current universe are ∼0.1 yr-1 Gpc-3 for hBH0s, and ∼0.01 yr-1 Gpc-3 for the sum of hBH1s and hBH2s, provided that the mass density of Population III stars is ∼1013M⊙ Gpc-3. These rates are modestly insensitive to initial conditions and single star models. The hBH1 and hBH2 mergers can dominate BH-BHs with hBHs discovered in the near future. They have low effective spins ≲0.2 in the current universe. The number ratio of hBH2s to hBH1s is high, ≳0.1. We also find that BHs in the mass gap (up to ∼85M⊙) merge. These merger rates can be reduced to nearly zero if Population III binaries are always wide (≳100R⊙), and if Population III stars always enter into chemically homogeneous evolution. The presence of close Population III binaries (∼10R⊙) is crucial for avoiding the worst scenario.

Keywords: Population III stars, Close binary stars, Massive stars, Stellar mass black holes, Gravitational waves, Astrophysical black holes, Common envelope binary stars
Radiative Scale Height and Shadows in Protoplanetary Disks. Planets form in young circumstellar disks called protoplanetary disks. However, it is still difficult to catch planet formation in situ. Nevertheless, from recent ALMA/SPHERE data, encouraging evidence of the direct and indirect presence of embedded planets has been identified in disks around young stars: co-moving point sources, gravitational perturbations, rings, cavities, and emission dips or shadows cast on disks. The interpretation of these observations needs a robust physical framework to deduce the complex disk geometry. In particular, protoplanetary disk models usually assume the gas pressure scale height given by the ratio of the sound speed over the azimuthal velocity H/r = cs/vk. By doing so, radiative pressure fields are often ignored, which could lead to a misinterpretation of the real vertical structure of such disks. We follow the evolution of a gaseous disk with an embedded Jupiter-mass planet through hydrodynamical simulations, computing the disk scale height including radiative pressure, which was derived from a generalization of the stellar atmosphere theory. We focus on the vertical impact of the radiative pressure in the vicinity of circumplanetary disks, where temperatures can reach ≳1000 K for an accreting planet and radiative forces can overcome gravitational forces from the planet. The radiation pressure effects create a vertical, optically thick column of gas and dust at the protoplanet location, casting a shadow in scattered light. This mechanism could explain the peculiar illumination patterns observed in some disks around young stars such as HD 169142 where a moving shadow has been detected or the extremely high aspect ratio H/r ∼ 0.2 observed in systems like AB Aur and CT Cha.

Keywords: Hydrodynamical simulations, Radiative transfer simulations, Planetary-disk interactions, Protoplanetary disks
The Thermal and Gravitational Energy Densities in the Large-scale Structure of the Universe. As cosmic structures form, matter density fluctuations collapse gravitationally and baryonic matter is shock-heated and thermalized. We therefore expect a connection between the mean gravitational potential energy density of collapsed halos, ${{\rm{\Omega }}}_{W}^{\mathrm{halo}}$ , and the mean thermal energy density of baryons, Ωth. These quantities can be obtained using two fundamentally different estimates: we compute ${{\rm{\Omega }}}_{W}^{\mathrm{halo}}$ using the theoretical framework of the halo model, which is driven by dark matter statistics, and measure Ωth using the Sunyaev-Zeldovich (SZ) effect, which probes the mean thermal pressure of baryons. First, we derive that, at the present time, about 90% of ${{\rm{\Omega }}}_{W}^{\mathrm{halo}}$ originates from massive halos with M &gt; 1013 M⊙. Then, using our measurements of the SZ background, we find that Ωth accounts for about 80% of the kinetic energy of the baryons available for pressure in halos at z ≲ 0.5. This constrains the amount of nonthermal pressure, e.g., due to bulk and turbulent gas motion sourced by mass accretion, to be about Ωnon-th ≃ 0.4 × 10-8 at z = 0.

Keywords: Cosmology, Galaxy dark matter halos, Galaxy clusters, Large-scale structure of the universe, Sunyaev-Zeldovich effect, Gravitational energy
Radial Velocity Monitoring of the Young Star Hubble 4: Disentangling Star-spot Lifetimes from Orbital Motion. We studied the weak-lined T Tauri star Hubble 4, a known long-period binary, and its star-spot phenomena. We used optical radial velocity (RV) data taken over a span of 14 yr (2004-2010, 2017-2019) at the McDonald Observatory 2.7 m Harlan J. Smith Telescope and single epoch imaging from the Hubble Space Telescope (HST)/Wide Field Camera 3 instrument. The observed and apparent RV variations show contributions, respectively, from the binary motion as well as from a large spot group on one of the stars, presumed to be the primary. Fitting and removing the orbital signal from the RVs, we found the lower bound on the lifetime of a previously identified large spot group on the surface of the star to be at least 5.1 yr. An ∼5 yr lower limit is a long, but not unprecedented, duration for a single spot group. The later epoch data indicate significant spot evolution has occurred, placing an upper bound on the spot group lifetime at 12 yr. We find that pre-main-sequence evolutionary models for the age of Taurus (∼2 Myr), combined with component mass estimates from the literature, permit us to reproduce the HST relative photometry and the binary-induced contribution to the apparent RV variations. The long-lived star spot we find on Hubble 4 has significant implications for dynamo models in young stars, as it adds evidence for long lifetimes of magnetic field topologies. There are also significant implications for young star exoplanet searches, as long-lived coherent RV signals may be spot induced and not the result of planetary motion. * This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

Keywords: Starspots, Binary stars, Stellar activity, T Tauri stars, Pre-main sequence stars, Stellar flares, Optical flares, Radial velocity
Convective Overshooting in the Envelopes of A-type Stars Using the k-ω Model. Mixing between convective zones is quite uncertain in the envelopes of A-type stars. To study the mixing in A-type envelopes, we use a new convection model, the k-ω model, in the MESA stellar evolution code. Using the k-ω model, we find that the overshooting regions of the He II and H/He I convection zones are integrated with each other. There is material exchange between the He II and H/He I convection zones through overshooting, in agreement with recent numerical simulations.We obtain the overshooting distance of about 3.5Hp below the base of the H/He I convection zone in a 2.3 M⊙ star. There are two overshooting regions beyond the He II convection zone in the same stellar model. We obtain that the overshooting distance of the upper one is about 3.9Hp and about 2.0Hp for the lower one. We find that the turbulent diffusion effect is particularly strong in the convective envelopes of A-type stars. In addition, we find that the typical size of the convective rolling cells is restricted by the actual thickness of the convective zones, because the thickness of the convection zones are usually smaller than or approximately equal to the local pressure scale height. Through comparisons with the results of the k-ω model, we find that a suitable value of fov is about 0.45 for the H/He I convective overshooting region. It is about 0.27 for the upper He II convective overshooting region and about 0.25 for the lower one.

Keywords: A stars, Stellar convection envelopes, Stellar evolution
An Oversized Magnetic Sheath Wrapping around the Parsec-scale Jet in 3C 273. In recent studies, several active galactic nuclei (AGNs) have exhibited gradients of the Faraday rotation measure (RM) transverse to their parsec-scale jet direction. Faraday rotation likely occurs as a result of a magnetized sheath wrapped around the jet. In the case of 3C 273, using Very Long Baseline Array multiepoch observations at 5, 8, and 15 GHz in 2009-2010, we observe that the jet RM has changed significantly toward negative values compared with that previously observed. These changes could be explained by a swing of the parsec-scale jet direction, which causes synchrotron emission to pass through different portions of the Faraday screen. We develop a model for the jet-sheath system in 3C 273 where the sheath is wider than the single-epoch narrow relativistic jet. We present our oversized sheath model together with a derived wide-jet full intrinsic opening angle αint = 2°1 and magnetic field strength B∣∣ = 3 μG, and thermal particle density Ne = 125 cm-3 at the wide jet-sheath boundary 230 pc downstream (deprojected) from its beginning. Most of the Faraday rotation occurs within the innermost layers of the sheath. The model brings together the jet direction swing and long-term RM evolution and may be applicable to other AGN jets that exhibit changes in their apparent jet direction.

Keywords: Radio jets, Quasars, Blazars, Very long baseline interferometry, Relativistic jets, Radio loud quasars, Active galactic nuclei, Polarimetry
Deciphering the Kinematic Structure of the Small Magellanic Cloud through Its Red Giant Population. We present a new kinematic model for the Small Magellanic Cloud (SMC), using data from the Gaia Data Release 2 catalog. We identify a sample of astrometrically well-behaved red giant (RG) stars belonging to the SMC and cross-match with publicly available radial velocity (RV) catalogs. We create a 3D spatial model for the RGs, using RR Lyrae for distance distributions, and apply kinematic models with varying rotation properties and a novel tidal expansion prescription to generate mock proper motion (PM) catalogs. When we compare this series of mock catalogs to the observed RG data, we find that a combination of moderate rotation (with a magnitude of ∼10-20 km s-1 at 1 kpc from the SMC center, inclination between ∼50 and 80°, and a predominantly north-to-south line-of-nodes position angle of ∼180°) and tidal expansion (with a scaling of ∼10 km s-1 kpc-1) is required to explain the PM signatures. The exact best-fit parameters depend somewhat on whether we assess only the PMs or include the RVs as a qualitative check, leaving some tension remaining between the PM and RV conclusions. In either case, the parameter space preferred by our model is different from previously inferred rotational geometries, including from the SMC H I gas, and from the RG RV-only analyses and new SMC PM analyses, which conclude that a rotation signature is not detectable. Taken together this underscores the need to treat the SMC as a series of different populations with distinct kinematics.

Keywords: Stellar motion, Galaxy dynamics, Small Magellanic Cloud, Galaxy interactions, Galaxy kinematics, Proper motions, Magellanic Clouds
Thermonuclear X-Ray Bursts with Late Secondary Peaks Observed from 4U 1608-52. We report the temporal and spectral analysis of three thermonuclear X-ray bursts from 4U 1608-52, observed by the Neutron Star Interior Composition Explorer (NICER) during and just after the outburst observed from the source in 2020. In two of the X-ray bursts, we detect secondary peaks 30 and 18 s after the initial peaks. The secondary peaks show a fast rise exponential decay-like shape resembling a thermonuclear X-ray burst. Time-resolved X-ray spectral analysis reveals that the peak flux, blackbody temperature, and apparent emitting radius values of the initial peaks are in agreement with X-ray bursts previously observed from 4U 1608-52, while the same values for the secondary peaks tend toward the lower end of the distribution of bursts observed from this source. The third X-ray burst, which happened during much lower accretion rates, did not show any evidence for a deviation from an exponential decay and was significantly brighter than the previous bursts. We present the properties of the secondary peaks and discuss the events within the framework of short recurrence time bursts or bursts with secondary peaks. We find that the current observations do not fit in standard scenarios and challenge our understanding of flame spreading.

Keywords: X-ray bursters
Connecting the Gravity Field, Moment of Inertia, and Core Properties in Jupiter through Empirical Structural Models. Constraining Jupiter's internal structure is crucial for understanding its formation and evolution history. Recent interior models of Jupiter that fit Juno's measured gravitational field suggest an inhomogeneous interior and potentially the existence of a diluted core. These models, however, strongly depend on the model assumptions and the equations of state used. A complementary modeling approach is to use empirical structural models. These can later be used to reveal new insights into the planetary interior and be compared to standard models. Here we present empirical structural models of Jupiter where the density profile is constructed by piecewise-polytropic equations. With these models we investigate the relation between the normalized moment of inertia (MoI) and the gravitational moments J2 and J4. Given that only the first few gravitational moments of Jupiter are measured with high precision, we show that an accurate and independent measurement of the MoI value could be used to further constrain Jupiter's interior. An independent measurement of the MoI with an accuracy better than ∼0.1% could constrain Jupiter's core region and density discontinuities in its envelope. We find that models with a density discontinuity at ∼1 Mbar, as would produce a presumed hydrogen-helium separation, correspond to a fuzzy core in Jupiter. We next test the appropriateness of using polytropes, by comparing them with empirical models based on polynomials. We conclude that both representations result in similar density profiles and ranges of values for quantities like core mass and MoI.

Keywords: Planetary cores, Planetary interior, Planetary structure
Large-scale Gravitational Lens Modeling with Bayesian Neural Networks for Accurate and Precise Inference of the Hubble Constant. We investigate the use of approximate Bayesian neural networks (BNNs) in modeling hundreds of time delay gravitational lenses for Hubble constant (H0) determination. Our BNN was trained on synthetic Hubble Space Telescope quality images of strongly lensed active galactic nuclei with lens galaxy light included. The BNN can accurately characterize the posterior probability density functions (PDFs) of model parameters governing the elliptical power-law mass profile in an external shear field. We then propagate the BNN-inferred posterior PDFs into an ensemble H0 inference, using simulated time delay measurements from a plausible dedicated monitoring campaign. Assuming well-measured time delays and a reasonable set of priors on the environment of the lens, we achieve a median precision of 9.3% per lens in the inferred H0. A simple combination of a set of 200 test lenses results in a precision of 0.5 km s-1 Mpc-1 (0.7%), with no detectable bias in this H0 recovery test. The computation time for the entire pipeline—including the generation of the training set, BNN training and H0 inference—translates to 9 minutes per lens on average for 200 lenses and converges to 6 minutes per lens as the sample size is increased. Being fully automated and efficient, our pipeline is a promising tool for exploring ensemble-level systematics in lens modeling for H0 inference.

Keywords: Cosmology, Publicly available software, Bayesian statistics, Strong gravitational lensing, Hubble constant, Hierarchical models
Multiwavelength Observations of the Formation and Eruption of a Complex Filament. We present an analysis of the formation and eruption of a filament and fast coronal mass ejection associated with a flare that occurred in active region 11429 using observations in the ultraviolet, extreme ultraviolet, X-ray, and radio wavelength bands. Precursor activity began as an interaction between two filaments, F1 and F2, that are identified as having twisted magnetic flux ropes (MFRs). Transient brightenings in all wavelengths are observed as a result of this interaction, likely the result of magnetic reconnection between the two filaments. This interaction results in a reconfiguration of the two filaments into a long overlying filament and a shorter low-lying filament. The upper filament subsequently undergoes a partial confined eruption. Plasma flows originating near the east footpoint of F1 lead to an extension of the upper filament into the filament channel to the west, resulting in a new active region filament (ARF). This new filament begins a slow rise and expansion. During its slowly rising phase, the MFR in which the filament is embedded becomes visible, with both the filament and flux rope rising and expanding simultaneously. The twist of the magnetic rope is determined as four turns. The erupting configuration changes from a twisted arch shape to a reversed γ shape within ∼75 s at the beginning of the fast-rise phase, representing a transformation from twist to writhe. The observations provide a clear example of filament formation via the tether-cutting reconnection of two nearby filaments. A helical kink instability may be the trigger of the ARF eruption.

Keywords: Solar flares, Solar filaments, Solar magnetic fields, Solar coronal mass ejections, Solar activity
Self-organized Criticality in Stellar Flares. Power-law size distributions are the hallmarks of nonlinear energy dissipation processes governed by self-organized criticality (SOC). Here we analyze 75 data sets of stellar flare size distributions, mostly obtained from the Extreme-Ultraviolet Explorer and the Kepler mission. We aim to answer the following questions for size distributions of stellar flares. (i) What are the values and uncertainties of power-law slopes? (ii) Do power-law slopes vary with time? (iii) Do power-law slopes depend on the stellar spectral type? (iv) Are they compatible with solar flares? (v) Are they consistent with SOC models? We find that the observed size distributions of stellar flare fluences (or energies) exhibit power-law slopes of αE = 2.09 ± 0.24 for optical data sets observed with Kepler. The observed power-law slopes do not show much time variability and do not depend on the stellar spectral type (M, K, G, F, A, giants). In solar flares, we find that background subtraction lowers the uncorrected value of αE = 2.20 ± 0.22 to αE = 1.57 ± 0.19. Furthermore, most of the stellar flares are temporally not resolved in low-cadence (30 minutes) Kepler data, which causes an additional bias. Taking these two biases into account, the stellar flare data sets are consistent with the theoretical prediction $N(x)\propto {x}^{-{\alpha }_{x}}$ of SOC models, i.e., αE = 1.5. Thus, accurate power-law fits require automated detection of the inertial range and background subtraction, which can be modeled with the generalized Pareto distribution, finite-system size effects, and extreme event outliers.

Keywords: Solar flares, Stellar flares, Astrostatistics, Stellar activity