Sazuna/UAT_keywords huggingface dataset:
Microphysics of Water Clouds in the Atmospheres of Y Dwarfs and Temperate Giant Planets. Water clouds are expected to form on Y dwarfs and giant planets with equilibrium temperatures near or below that of Earth, drastically altering their atmospheric compositions and their albedos and thermal emission spectra. Here we use the 1D Community Aerosol and Radiation Model for Atmospheres (CARMA) to investigate the microphysics of water clouds on cool substellar worlds to constrain their typical particle sizes and vertical extent, taking into consideration nucleation and condensation, which have not been considered in detail for water clouds in H/He atmospheres. We compute a small grid of Y-dwarf and temperate giant-exoplanet atmosphere models with water clouds forming through homogeneous nucleation and heterogeneous nucleation on cloud condensation nuclei composed of meteoritic dust, organic photochemical hazes, and upwelled potassium chloride cloud particles. We present comparisons with the Ackerman &amp; Marley parameterization of cloud physics to extract the optimal sedimentation efficiency parameter (f sed) using Virga. We find that no Virga model replicates the CARMA water clouds exactly and that a transition in f sed occurs from the base of the cloud to the cloud top. Furthermore, we generate simulated thermal emission and geometric albedo spectra and find large, wavelength-dependent differences between the CARMA and Virga models, with different gas absorption bands reacting differently to the different cloud distributions and particularly large differences in the M band. Therefore, constraining the vertically dependent properties of water clouds will be essential to estimate the gas abundances in these atmospheres.

Keywords: Exoplanet atmospheric composition , Brown dwarfs, Atmospheric clouds, Y dwarfs, Planetary atmospheres, Extrasolar gaseous giant planets, Exoplanet atmospheres
Surveys of Clumps, Cores, and Condensations in Cygnus X. II. Radio Properties of Massive Dense Cores. We have carried out a high-sensitivity and high-resolution radio continuum study toward a sample of 47 massive dense cores (MDCs) in the Cygnus X star-forming complex using the Karl G. Jansky Very Large Array, aiming to detect and characterize the radio emission associated with star-forming activities down to ~0.01 pc scales. We have detected 64 radio sources within or closely around the FWHMs of the MDCs, of which 37 are reported for the first time. The majority of the detected radio sources are associated with dust condensations embedded within the MDCs, and they are mostly weak and compact. We are able to build spectral energy distributions for eight sources. Two of them indicate nonthermal emission and the other six indicate thermal free-free emission. We have determined that most of the radio sources are ionized jets or winds originating from massive young stellar objects, whereas only a few sources are likely to be ultracompact H II regions. Further quantitative analyses indicate that the radio luminosity of the detected radio sources increases along the evolution path of the MDCs.

Keywords: Protostars, Star formation, Radio jets, H II regions
AMBER: A Semi-numerical Abundance Matching Box for the Epoch of Reionization. The Abundance Matching Box for the Epoch of Reionization (AMBER) is a semi-numerical code for modeling the cosmic dawn. The new algorithm is not based on the excursion set formalism for reionization, but takes the novel approach of calculating the reionization-redshift field ${z}_{\mathrm{re}}({\boldsymbol{x}})$ assuming that hydrogen gas encountering higher radiation intensity are photoionized earlier. Redshift values are assigned while matching the abundance of ionized mass according to a given mass-weighted ionization fraction ${\bar{x}}_{{\rm{i}}}(z)$ . The code has the unique advantage of allowing users to directly specify the reionization history through the redshift midpoint z mid, duration Δz, and asymmetry A z input parameters. The reionization process is further controlled through the minimum halo mass M min for galaxy formation and the radiation mean free path l mfp for radiative transfer. We implement improved methods for constructing density, velocity, halo, and radiation fields, which are essential components for modeling reionization observables. We compare AMBER with two other semi-numerical methods and find that our code more accurately reproduces the results from radiation-hydrodynamic simulations. The parallelized code is over four orders of magnitude faster than radiative transfer simulations and will efficiently enable large-volume models, full-sky mock observations, and parameter-space studies. AMBER will be made publicly available to facilitate and transform studies of the Epoch of Reionization.

Keywords: Cosmology, Large-scale structure of the universe, Computational methods, Intergalactic medium, Reionization
Dynamic Time Warping as a Means of Assessing Solar Wind Time Series. Over the last decades, international attempts have been made to develop realistic space weather prediction tools aiming to forecast the conditions on the Sun and in the interplanetary environment. These efforts have led to the development of appropriate metrics to assess the performance of those tools. Metrics are necessary to validate models, to compare different models, and to monitor the improvements to a certain model over time. In this work, we introduce dynamic time warping (DTW) as an alternative way of evaluating the performance of models and, in particular, of quantifying the differences between observed and modeled solar wind time series. We present the advantages and drawbacks of this method, as well as its application to Wind observations and EUHFORIA predictions at Earth. We show that DTW can warp sequences in time, aiming to align them with the minimum cost by using dynamic programming. It can be applied for the evaluation of modeled solar wind time series in two ways. The first calculates the sequence similarity factor, a number that provides a quantification of how good the forecast is compared to an ideal and a nonideal prediction scenario. The second way quantifies the time and amplitude differences between the points that are best matched between the two sequences. As a result, DTW can serve as a hybrid metric between continuous measurements (e.g., the correlation coefficient) and point-by-point comparisons. It is a promising technique for the assessment of solar wind profiles, providing at once the most complete evaluation portrait of a model.

Keywords: Space weather, Magnetohydrodynamics, Solar wind, Time series analysis
Fine-grained Rim Formation via Kinetic Dust Aggregation in Shock Waves Around Evaporating Icy Planetesimals. Fine-grained rims (FGRs) are frequently found around chondrules in primitive chondrites. The remarkable feature of FGRs is their submicron-sized and nonporous nature. The typical thickness of FGRs around chondrules is 10-100 μm. Recently, a novel idea was proposed for the origin of FGRs: high-speed collisions between chondrules and fine dust grains called the kinetic dust aggregation process. Experimental studies revealed that (sub)micron-sized ceramic particles can stick to a ceramic substrate in a vacuum when the impact velocity is approximately in the range of 0.1-1 km s-1. In this study, we examine the possibility of FGR formation via kinetic dust aggregation in chondrule-forming shock waves. When shock waves are created by undifferentiated icy planetesimals, fine dust grains would be released from the planetary surface due to the evaporation of icy planetesimals. We consider the dynamics of chondrules behind the shock front and calculate the growth of FGRs via kinetic dust aggregation based on simple one-dimensional calculations. We found that nonporous FGRs with a thickness of 10-100 μm would be formed in shock waves around evaporating icy planetesimals.

Keywords: Shocks, Chondrules, Chondrites, Planetesimals
Cold Gas in Massive Galaxies as a Critical Test of Black Hole Feedback Models. Black hole feedback has been widely implemented as the key recipe to quench star formation in massive galaxies in modern semianalytic models and hydrodynamical simulations. As the theoretical details surrounding the accretion and feedback of black holes continue to be refined, various feedback models have been implemented across simulations, with notable differences in their outcomes. Yet, most of these simulations have successfully reproduced some observations, such as the stellar mass function and star formation rate density in the local universe. We use the recent observation of the change in the neutral hydrogen gas mass (including both H2 and H I) with the star formation rate of massive central disk galaxies as a critical constraint of black hole feedback models across several simulations. We find that the predictions of IllustrisTNG agree with the observations much better than the other models tested in this work. This favors IllustrisTNG's treatment of active galactic nuclei (AGN)-where kinetic winds are driven by black holes at low accretion rates-as more plausible among those we test. In turn, this also indirectly supports the idea that the massive central disk galaxy population in the local universe was likely quenched by AGN feedback.

Keywords: Galaxies
MAXI and NuSTAR Observations of the Faint X-Ray Transient MAXI J1848-015 in the GLIMPSE-C01 Cluster. We present the results of Monitor of All-sky X-ray Image (MAXI) monitoring and two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the recently discovered faint X-ray transient MAXI J1848015. Analysis of the MAXI light curve shows that the source underwent a rapid flux increase beginning on 2020 December 20, followed by a rapid decrease in flux after only ~5 days. NuSTAR observations reveal that the source transitioned from a bright soft state with unabsorbed, bolometric (0.1-100 keV) flux F = 6.9 ± 0.1 × 10-10 erg cm-2 s-1, to a low hard state with flux F = 2.85 ± 0.04 × 10-10 erg cm-2 s-1. Given a distance of 3.3 kpc, inferred via association of the source with the GLIMPSE-C01 cluster, these fluxes correspond to an Eddington fraction of the order of 10-3 for an accreting neutron star (NS) of mass M = 1.4M ⊙, or even lower for a more massive accretor. However, the source spectra exhibit strong relativistic reflection features, indicating the presence of an accretion disk that extends close to the accretor, for which we measure a high spin, a = 0.967 ± 0.013. In addition to a change in flux and spectral shape, we find evidence for other changes between the soft and hard states, including moderate disk truncation with the inner disk radius increasing from R in ≈ 3 R g to R in ≈ 8 R g, narrow Fe emission whose centroid decreases from 6.8 ± 0.1 keV to 6.3 ± 0.1 keV, and an increase in low-frequency (10-3-10-1 Hz) variability. Due to the high spin, we conclude that the source is likely to be a black hole rather than an NS, and we discuss physical interpretations of the low apparent luminosity as well as the narrow Fe emission.

Keywords: Accretion, Neutron stars, X-ray binary stars, Black holes, High energy astrophysics, Stellar mass black holes, Compact objects
Identifying Lensed Quasars and Measuring Their Time Delays from Unresolved Light Curves. Identifying multiply imaged quasars is challenging owing to their low density in the sky and the limited angular resolution of wide-field surveys. We show that multiply imaged quasars can be identified using unresolved light curves, without assuming a light-curve template or any prior information. After describing our method, we show, using simulations, that it can attain high precision and recall when we consider high-quality data with negligible noise well below the variability of the light curves. As the noise level increases to that of the Zwicky Transient Facility telescope, we find that precision can remain close to 100% while recall drops to ~60%. We also consider some examples from Time Delay Challenge 1 and demonstrate that the time delays can be accurately recovered from the joint light-curve data in realistic observational scenarios. We further demonstrate our method by applying it to publicly available COSMOGRAIL data of the observed lensed quasar SDSS J1226-0006. We identify the system as a lensed quasar based on the unresolved light curve and estimate a time delay in good agreement with the one measured by COSMOGRAIL using the individual image light curves. The technique shows great potential to identify lensed quasars in wide-field imaging surveys, especially the soon-to-be-commissioned Vera Rubin Observatory.

Keywords: Time series analysis
Fitting AGN/Galaxy X-Ray-to-radio SEDs with CIGALE and Improvement of the Code. Modern and future surveys effectively provide a panchromatic view for large numbers of extragalactic objects. Consistently modeling these multiwavelength survey data is a critical but challenging task for extragalactic studies. The Code Investigating GALaxy Emission (CIGALE) is an efficient PYTHON code for spectral energy distribution (SED) fitting of galaxies and active galactic nuclei (AGNs). Recently, a major extension of CIGALE (named X-CIGALE) has been developed to account for AGN/galaxy X-ray emission and improve AGN modeling at UV-to-IR wavelengths. Here, we apply X-CIGALE to different samples, including Cosmological Evolution Survey (COSMOS) spectroscopic type 2 AGNs, Chandra Deep Field-South X-ray detected normal galaxies, Sloan Digital Sky Survey quasars, and COSMOS radio objects. From these tests, we identify several weaknesses of X-CIGALE and improve the code accordingly. These improvements are mainly related to AGN intrinsic X-ray anisotropy, X-ray binary emission, AGN accretion-disk SED shape, and AGN radio emission. These updates improve the fit quality and allow for new interpretation of the results, based on which we discuss physical implications. For example, we find that AGN intrinsic X-ray anisotropy is moderate, and can be modeled as ${L}_{X}(\theta )\propto 1+\cos \theta $ , where θ is the viewing angle measured from the AGN axis. We merge the new code into the major branch of CIGALE, and publicly release this new version as CIGALE V2022.0 on https://cigale.lam.fr.

Keywords: Open source software, X-ray binary stars, Astronomy software, Quasars, Active galactic nuclei, Spectral energy distribution, X-ray active galactic nuclei, Radio active galactic nuclei, Radio sources
Revisiting Christoph Scheiner's Sunspot Records: A New Perspective on Solar Activity of the Early Telescopic Era. Christoph Scheiner was one of the most outstanding astronomers in the history of sunspot observations. His book, Rosa Ursina, is the reference work regarding the study of the earliest sunspot records. The sunspot observations compiled by Scheiner in Rosa Ursina and Prodomus, including records made by other observers, forms one of the main references of the observations known for that period-particularly around the 1620s. Thus, his work is crucial to determine the solar activity level of the first solar cycles of the telescopic era. The number of sunspot groups recorded in Scheiner's documentary sources has been included in the existing sunspot group number databases. However, we have detected significant errors in the number of groups currently assigned to Scheiner's records. In this work, we reanalyze the information in Scheiner's source documents. Consequently, the standard 11 yr solar cycle shape for the second solar cycle of the telescopic era, which is not clear in previous studies, now becomes evident. In addition, the highest daily number of groups recorded during this cycle (eight groups) is 20% less than in the one included in the existing sunspot group number databases. Using the hypergeometrical probability distribution, we find that solar minima in 2008-2009 and 2018-2019 are comparable to the most probable solar activity level of the minimum around 1632. In particular, the estimated lower limit for the solar activity in 1632 is even comparable with the solar activity level in 2008 and 2018.

Keywords: Solar activity, The Sun, Sunspots, Solar cycle
Accreting on the Edge: A Luminosity-dependent Cyclotron Line in the Be/X-Ray Binary 2S 1553-542 Accompanied by Accretion Regimes Transition. Accreting X-ray pulsars undergo luminous X-ray outbursts during which the luminosity-dependent spectral and timing features of the neutron star's emission can be analyzed in detail, thus shedding light on the accretion regime at work. We took advantage of a monitoring campaign that was performed with NuSTAR, Swift/XRT, AstroSat and NICER to follow the Be/X-ray Binary 2S 1553-542 along one of its rare outbursts, and thus trace its spectral and timing evolution. We report the discovery of a luminosity-dependent cyclotron line energy for the first time in this source. The pulse profiles and pulsed fraction also show variability along the outburst, which is consistent with the interpretation that the source transitions from the subcritical to the supercritical accretion regime, separated by a critical luminosity of L crit ≈ 4 × 1037 erg s-1.

Keywords: Stellar accretion disks, Neutron stars, X-ray binary stars, Magnetic fields
Selection Effects in Periodic X-Ray Data from Maximizing Detection Statistics. The Neutron Star Interior Composition Explorer (NICER) records exceptional data on pulsars' energy-dependent X-ray pulse profiles. However, in searching for evidence of pulsations, Guillot et al. (2019) introduce a procedure to select an ordered subset of data that maximizes a detection statistic (the H-test). I show that this can degrade subsequent analyses using an idealized model with stationary expected count rates from both noise and signal. Specifically, the data-selection procedure biases the inferred mean count rate to be too low and the inferred pulsation amplitude to be too high, and the size of these biases scales strongly with the amount of data that is rejected and the true signal amplitude. The procedure also alters the H-test's null distribution, rendering nominal significance estimates overly optimistic. While the idealized model does not capture all the complexities of real NICER data, it suggests that these biases could be important for NICER's observations of J0740+6620 and other faint pulsars (observations of J0030+0451 are likely less affected). I estimate that these effects may introduce a bias of ${ \mathcal O }(10 \% )$ on average in the inferred modulation depth of lightcurves like J0740+6620's, and may be as large as ${ \mathcal O }(50 \% )$ for fainter pulsars. However, the change for a single data set like J0740+6620 is expected to be a shift between -5% and +20%. This could imply that the lower limit on J0740+6620's radius is slightly larger than it should be, although preliminary investigations suggest the radius constraints shift to larger radii by ${ \mathcal O }(1 \% )$ with the same overall statistical precision using real J0740+6620 data.

Keywords: X-ray astronomy, Neutron stars, Pulsars, Nuclear astrophysics, Compact objects
Impact of 3D Structure on Magnetic Reconnection. Results from 2.5D and 3D studies of the onset and development of the tearing instability are presented, using high-fidelity resistive MHD simulations. A limited parameter study of the strength of the reconnecting field (or shear angle) was performed. An initially simple 1D equilibrium was used, consisting of a modified force-free current sheet, with periodic boundary conditions in all directions. In all cases, the linear and nonlinear evolution led to a primary current sheet between two large flux ropes. The global reconnection rate during this later stage was analyzed in all simulations. It was found that in 2.5D the primary current sheet fragmented owing to plasmoids, and as expected, the global reconnection rate, calculated using multiple methods, increases with the strength of the reconnecting field owing to a stronger Alfvén speed. In 3D, the presence of interacting oblique modes of the tearing instability complicates the simple 2.5D picture, entangling the magnetic field of the inflow and introducing a negative effect on the reconnection rate. The two competing effects of stronger Alfvén speed and entangling, which both increase with the strength of the reconnecting field, resulted in a decrease in the reconnection rate with increasing reconnecting field. For all simulations, the 3D rates were less than in 2.5D but suggest that as one goes to weak reconnecting field (or strong guide field) the system becomes more 2.5D-like and the 2.5D and 3D rates converge. These results have relevance to situations like nanoflare heating and flare current sheets in the corona.

Keywords: Solar atmosphere, Magnetohydrodynamics, Solar flares, Solar magnetic reconnection, Solar physics, Solar corona, Solar magnetic fields
Investigating the Blazar TXS 0506+056 through Sharp Multiwavelength Eyes During 2017-2019. The blazar TXS 0506+056 got into the spotlight of the astrophysical community in 2017 September, when a high-energy neutrino detected by IceCube (IceCube-170922A) was associated at the 3σ level with a γ-ray flare from this source. This multi-messenger photon-neutrino association remains, as per today, the most significant association ever observed. TXS 0506+056 was a poorly studied object before the IceCube-170922A event. To better characterize its broadband emission, we organized a multiwavelength campaign lasting 16 months (2017 November to 2019 February), covering the radio band (Metsähovi, OVRO), the optical/UV (ASAS-SN, KVA, REM, Swift/UVOT), the X-rays (Swift/XRT, NuSTAR), the high-energy γ rays (Fermi/LAT), and the very high-energy (VHE) γ rays (MAGIC). In γ rays, the behavior of the source was significantly different from the behavior in 2017: MAGIC observations show the presence of flaring activity during 2018 December, while the source only shows an excess at the 4σ level during the rest of the campaign (74 hr of accumulated exposure); Fermi/LAT observations show several short (on a timescale of days to a week) flares, different from the long-term brightening of 2017. No significant flares are detected at lower energies. The radio light curve shows an increasing flux trend that is not seen in other wavelengths. We model the multiwavelength spectral energy distributions in a lepto-hadronic scenario, in which the hadronic emission emerges as Bethe-Heitler and pion-decay cascade in the X-rays and VHE γ rays. According to the model presented here, the 2018 December γ-ray flare was connected to a neutrino emission that was too brief and not bright enough to be detected by current neutrino instruments.

Keywords: Blazars, Jets, Gamma-rays, High energy astrophysics