bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficient Stochastic Template Bank Using Inner Product Inequalities
Authors: Kacanja Keisi , Nitz Alexander H. , Wu Shichao , Cusinato Marco , Dhurkunde Rahul , Harry Ian , Dal Canton Tito , Pannarale Francesco 
Published: November 2024

Abstract
Gravitational wave searches are crucial for studying compact sources such as neutron stars and black holes. Many sensitive modeled searches use matched filtering to compare gravitational strain data to a set of waveform models known as template banks. We introduce a new stochastic placement method for constructing template banks, offering efficiency and flexibility to handle arbitrary parameter spaces, including orbital eccentricity, tidal deformability, and other extrinsic parameters. This method can be computationally limited by the ability to compare proposal templates with the accepted templates in the bank. To alleviate this computational load, we introduce the use of inner product inequalities to reduce the number of required comparisons. We also introduce a novel application of Gaussian Kernel Density Estimation to enhance waveform coverage in sparser regions. Our approach has been employed to search for eccentric binary neutron stars, low-mass neutron stars, primordial black holes, and supermassive black hole binaries. We demonstrate that our method produces self-consistent banks that recover the required minimum fraction of signals. For common parameter spaces, our method shows comparable computational performance and similar template bank sizes to geometric placement methods and stochastic methods, while easily extending to higher-dimensional problems. The time to run a search exceeds the time to generate the bank by a factor of

O
(

10

5

)

for dedicated template banks, such as geometric, mass-only stochastic, and aligned spin cases,

O
(

10

4

)

for eccentric and

O
(

10

3

)

for the tidal deformable bank. With the advent of efficient template bank generation, the primary area for improvement is developing more efficient search methodologies.
Radiative Pressure on Fractal Dust Grains in Oxygen-rich AGB Stars
Authors: Ferguson Frank T. , Nuth Joseph A. , Paquette John A. 
Published: November 2024

Abstract
There is still considerable debate on the exact composition of grains formed in the outflows of O-rich, asymptotic giant branch stars. Estimates of the expected condensation distances based on radiative transfer calculations show that iron-free silicates can condense close to the star but typically lack the opacity to drive an outflow unless they are large enough that radiation pressure due to scattering on the grains becomes significant. Iron-containing silicates have a much higher absorption opacity, but due to this stronger absorption, their expected condensation location is well beyond the expected dust formation zone. Recent measurements of the efficiency of SiO condensational growth have shown that this rate is low. The result of this low growth efficiency is that nucleation may persist for longer, giving a larger number of smaller primary particles, leading to an increased likelihood of particle aggregation in these outflows. In this work, we examine how the radiation pressure changes with the possible aggregation of these primary particles into fractal aggregates. Opacity calculations are made using optical properties of both forsterite and astronomical silicate for aggregates containing up to 256 primary particles and for fractal dimensions of 1.8 and 2.8. For primary particles of radius less than ∼0.1 μm, aggregation leads to an enhancement of the radiation pressure over an equivalent cloud of isolated primary particles.
Memory in the Burst Occurrence of Repeating Fast Radio Bursts
Authors: Wang Ping , Song Li-Ming , Xiong Shao-Lin , Zhao Xiao-Yun , Wang Jin , Zhao Shu-Min , Xiao Shuo , Cai Ce , Xie Sheng-Lun , Xue Wang-Chen , Wang Chen-Wei , Wang Yue , Zhang Wen-Long 
Published: November 2024

Abstract
Understanding the nature of repeating fast radio bursts (FRBs) is crucial for probing their underlying physics. In this work, we analyze the waiting time statistics between bursts of three repeating FRBs from four data sets. We find a universally pronounced dependency of the waiting times on the previous time interval (denoted as λ
0). We observe a temporal clustering, where short waiting times tend to be followed by short ones and long by long, comparative to their mean value. This memory dependency is manifested in the conditional mean waiting time as well as in the conditional mean residual time to the next burst, both of which increase in direct proportion to λ
0. Consequently, the likelihood of experiencing a subsequent FRB burst within a given time window after the preceding burst is generally influenced by the burst history. We reveal, for the first time, that these memory effects are present in the scale-invariant preconditioned waiting time distribution. We show that the memory effect provides a unified description of waiting times that may account for both the repeating FRBs and the apparently nonrepeating FRBs (i.e., those only observed one time). These results shed new light on the mechanism of FRBs.
Measurements of Sunspot Group Tilt Angles Based on SOHO/MDI and SDO/HMI Magnetograms
Authors: Zeng Shu-Guang , Zhao Ao-Yu , Yi Shuang , Zheng Sheng , Zeng Xiang-Yun , Deng Lin-Hua , Huang Yao 
Published: November 2024

Abstract
The tilt angle of sunspot groups plays a crucial role in solar dynamo models for the generation of the poloidal field, yet the statistical properties of the tilt angle are not fully comprehended. This study employs magnetograms from the Solar and Heliospheric Observatory/Michelson Doppler Imager and Solar Dynamics Observatory/Helioseismic and Magnetic Imager to measure the tilt angles of 11,373 sunspot groups over the period from 2008 to 2023. This comprehensive analysis examines the relationship between the tilt angle and latitude of the sunspot groups, as well as the correlation between the tilt angle and solar cycle strength. The methodology involves calculating tilt angles within the ±45° central meridian distance, comparing mean-based and median-based measurements, and applying specific angular separation criteria. The findings reveal that during solar cycle 24, the tilt angles increase by approximately 4° for every 10° increase in latitude, in line with Joy’s law. A significant anticorrelation is observed between the latitude-normalized tilt angle (γ/∣L∣) and solar cycle strength. The research also uncovers a substantial hemispheric asymmetry in tilt angle parameters, with the southern hemisphere (m
Joy: 0.23 ± 0.092 ∼ 0.24 ± 0.074, γ = 8.°14 ± 0.°43 ∼ 9.°04 ± 0.°486) consistently showing larger tilt angles than the northern hemisphere (m
Joy: 0.47 ± 0.096 ∼ 0.51 ± 0.062, γ = 6.°14 ± 0.°304 ∼ 6.°64 ± 0.°334).
Convective Magnetic Flux Emergence Simulations from the Deep Solar Interior to the Photosphere: Comprehensive Study of Flux Tube Twist
Authors: Toriumi Shin , Hotta Hideyuki , Kusano Kanya 
Published: November 2024

Abstract
The emergence of magnetic flux from the deep convection zone plays an important role in solar magnetism, such as the generation of active regions and triggering of various eruptive phenomena, including jets, flares, and coronal mass ejections. To investigate the effects of magnetic twist on flux emergence, we performed numerical simulations of flux tube emergence using the radiative magnetohydrodynamic code R2D2 and conducted a systematic survey on the initial twist. Specifically, we varied the twist of the initial tube both positively and negatively from zero to twice the critical value for kink instability. As a result, regardless of the initial twist, the flux tube was lifted by the convective upflow and reached the photosphere to create sunspots. However, when the twist was too weak, the photospheric flux was quickly diffused and not retained long as coherent sunspots. The degree of magnetic twist measured in the photosphere conserved the original twist relatively well and was comparable to actual solar observations. Even in the untwisted case, a finite amount of magnetic helicity was injected into the upper atmosphere because the background turbulence added helicity. However, when the initial twist exceeded the critical value for kink instability, the magnetic helicity normalized by the total magnetic flux was found to be unreasonably larger than the observations, indicating that the kink instability of the emerging flux tube may not be a likely scenario for the formation of flare-productive active regions.
A Data-driven Magnetohydrodynamic Simulation of the 2011 February 15 Coronal Mass Ejection from Active Region NOAA 11158
Authors: Fan Yuhong , Kazachenko Maria D. , Afanasyev Andrey N. , Fisher George H. 
Published: November 2024

Abstract
We present a boundary data-driven magnetohydrodynamic (MHD) simulation of the 2011 February 15 coronal mass ejection (CME) event of Active Region NOAA 11158. The simulation is driven at the lower boundary with an electric field derived from the normal magnetic field and the vertical electric current measured from the Solar Dynamics Observatory (SDO) Helioseismic Magnetic Imager vector magnetograms. The simulation shows the buildup of a pre-eruption coronal magnetic field that is close to the nonlinear force-free field extrapolation, and it subsequently develops multiple eruptions. The sheared/twisted field lines of the pre-eruption magnetic field show qualitative agreement with the brightening loops in the SDO Atmospheric Imaging Assembly (AIA) hot passband images. We find that the eruption is initiated by the tether-cutting reconnection in a highly sheared field above the central polarity inversion line and a magnetic flux rope with dipped field lines forms during the eruption. The modeled erupting magnetic field evolves to develop a complex structure containing two distinct flux ropes and produces an outgoing double-shell feature consistent with the Solar Terrestrial Relations Observatory B/Extreme UltraViolet Imager observation of the CME. The foot points of the erupting field lines are found to correspond well with the dimming regions seen in the SDO/AIA observation of the event. These agreements suggest that the derived electric field is a promising way to drive MHD simulations to establish the realistic pre-eruption coronal field based on the observed vertical electric current and model its subsequent dynamic eruption.
Formation of Jupiter-mass Binary Objects through Photoerosion of Fragmenting Cores
Authors: Diamond Jessica L. , Parker Richard J. 
Published: November 2024

Abstract
The recent discovery of tens of Jupiter-mass binary objects (JuMBOs) in the Orion Nebula Cluster (ONC) with the James Webb Space Telescope has intensified the debate on the origin of free-floating planetary mass objects within star-forming regions. The JuMBOs have masses below the opacity limit for fragmentation but have very wide separations (from tens to hundreds of astronomical units), suggesting that they did not form in a similar manner to other substellar mass binaries. Here, we propose that the theory of photoerosion of prestellar cores by Lyman continuum radiation from massive stars could explain the JuMBOs in the ONC. We find that for a range of gas densities the final substellar mass is comfortably within the JuMBO mass range, and the separations of the JuMBOs are consistent with those of more massive (G- and A-type) binaries, which would have formed from the fragmentation of the cores had they not been photoeroded. The photoerosion mechanism is most effective within the H ii region(s) driven by the massive star(s). The majority of the observed JuMBOs lie outside of these regions in the ONC, but they may have formed within them and then subsequently migrated due to dynamical evolution.
On the Acceleration of the Young Solar Wind from Different Source Regions
Authors: Jiao Yiming , Liu Ying D. , Cheng Wenshuai , Ran Hao , Wang Rui 
Published: November 2024

Abstract
The acceleration of the young solar wind is studied using the first 17 encounters of the Parker Solar Probe. We identify wind intervals from different source regions: coronal hole (CH) interiors, streamers, and low-Mach-number boundary layers (LMBLs), i.e., the inner boundaries of coronal holes. We present their statistical trends in the acceleration process. Most of the observations can be reproduced by a two-fluid hydrodynamic model with realistic corona temperatures. In such a model, the solar wind is accelerated by the combined thermal pressures of protons and electrons, but it is mainly the difference in the proton pressure that leads to the difference in the solar wind speed. The proton pressure is the highest in the fastest CH wind, with a high initial proton temperature that decreases slowly. It is lower in the relatively slow LMBL wind and the lowest in the slowest streamer wind. The proton temperature is quadratically correlated with the wind speed when scaled to the same distance. In contrast, the electron temperature shows no significant differences for different wind types or wind speeds, indicating more similar contributions from the electron pressure. The model gives reasonable locations for the sonic critical point, which is on average at 3.6–7.3 Rs
and can also extend to large distances when the proton temperature is extremely low, as in the LMBL wind. In addition to the thermal pressure, we raise the possibility that Alfvén waves may contribute to the solar wind acceleration, especially for the fast CH wind.
Probing the Low-velocity Regime of Nonradiative Shocks with Neutron Star Bow Shocks
Authors: Ocker Stella Koch , Cosens Maren 
Published: November 2024

Abstract
Nonradiative shocks accelerate particles and heat astrophysical plasmas. While supernova remnants are the most well-studied example, neutron star (NS) bow shocks are also nonradiative and Balmer dominated. NS bow shocks are likely ubiquitous in the interstellar medium due to their large speeds imparted at birth, and they are thought to be a discrete source population contributing to the Galactic cosmic-ray spectrum. To date, nine NS bow shocks have been directly observed in Hα images. Most of these shocks have been characterized using narrowband Hα imaging and slit spectroscopy, which do not resolve the multicomponent velocity structure of the shocks and their spatial geometry. Here we present integral field spectroscopy of three NS bow shocks: J0742−2822, J1741−2054, and J2225+6535 (the Guitar Nebula). We measure the shock properties simultaneously in four dimensions: the 2D projected shock morphology, the radial velocity structure, and the Hα flux. The broad-to-narrow line ratio (I
b/I
n) is inferred from radial velocity profiles, and for J1741−2054, the narrow line is detected in multiple regions of the shock. The inferred line ratios and widths suggest that NS bow shocks represent a low-shock velocity regime (V ≲ 200 km s−1) in which I
b/I
n is high, distinct from the shock regime probed by supernova remnants. Our results illustrate a need for nonradiative shock models at velocities lower than previously considered, which will reveal the electron–ion temperature ratios and particle acceleration efficiencies of these bow shocks.
The Polar Vortex Hypothesis: Evolving, Spectrally Distinct Polar Regions Explain Short- and Long-term Light-curve Evolution and Color–Inclination Trends in Brown Dwarfs and Giant Exoplanets
Authors: Fuda Nguyen , Apai Dániel 
Published: November 2024

Abstract
Recent studies revealed viewing-angle-dependent color and spectral trends in brown dwarfs, as well as long-term photometric variability (∼100 hr). The origins of these trends are yet unexplained. Here, we propose that these seemingly unrelated sets of observations stem from the same phenomenon: the polar regions of brown dwarfs and directly imaged exoplanets are spectrally different from lower-latitude regions, and they evolve over longer timescales, possibly driven by polar vortices. We explore this hypothesis via a spatiotemporal atmosphere model capable of simulating time series and disk-integrated spectra of ultracool atmospheres. We study three scenarios with different spectral and temporal components: a null hypothesis without polar vortex, and two scenarios with polar vortices. We find that the scenarios with polar vortex can explain the observed infrared color–inclination trend and the variability amplitude–inclination trend. The presence of spectrally distinct, time-evolving polar regions in brown dwarfs and giant exoplanet atmospheres raises the possibility that one-dimensional static atmospheric models may be insufficient for reproducing ultracool atmospheres in detail.
Astroparticles from X-Ray Binary Coronae
Authors: Fang K. , Halzen Francis , Heinz Sebastian , Gallagher John S. 
Published: November 2024

Abstract
The recent observation of high-energy neutrinos from the Galactic plane implies an abundant population of hadronic cosmic-ray sources in the Milky Way. We explore the role of the coronae of accreting stellar-mass black holes as such astroparticle emitters. We show that the particle acceleration and interaction timescales in the coronal region are tied to the compactness of the X-ray source. Thus, neutrino emission processes may similarly happen in the cores of active galactic nuclei and black hole X-ray binaries (XRBs), despite their drastically different masses and physical sizes. We apply the model to the well-measured XRB Cygnus X-1 and find that the cascaded gamma rays accompanying the neutrino emission naturally explain the GeV emission that only presents during the source’s hard state, while the state-averaged gamma-ray emission explains the LHAASO observation above 20 TeV. We show that XRB coronae could contribute significantly to the Galactic cosmic-ray and Galactic plane neutrino fluxes. Our model predicts variable high-energy neutrino emission from bright Galactic XRBs that may be observed by IceCube and future neutrino observatories.
Dynamics of Binary Planets within Star Clusters
Authors: Huang 黄 Yukun 宇坤 , Zhu 祝 Wei 伟 , Kokubo 小久 Eiichiro 保英一郎 
Published: November 2024

Abstract
We develop analytical tools and perform three-body simulations to investigate the orbital evolution and dynamical stability of binary planets within star clusters. Our analytical results show that the orbital stability of a planetary-mass binary against passing stars is mainly related to its orbital period. Critical flybys, defined as stellar encounters with energy kicks comparable to the binary binding energy, can efficiently produce a wide range of semimajor axes (a) and eccentricities (e) from a dominant population of primordially tight Jupiter-mass binary objects (JuMBOs). The critical flyby criterion we derived offers an improvement over the commonly used tidal radius criterion, particularly in high-speed stellar encounters. Applying our results to the recently discovered JuMBOs by the James Webb Space Telescope (JWST), our simulations suggest that to match the observed ∼9% wide binary fraction, an initial semimajor axis of a
0 ∼ 10–20 au and a density-weighted residence time of χ ≳ 104 Myr pc−3 are favored. These results imply that the JWST JuMBOs probably formed as tight binaries near the cluster core.
Spectral Characteristics of Fundamental–Harmonic Pairs of Interplanetary Type III Radio Bursts Observed by PSP
Authors: Chen 陈 Ling 玲 , Ma 马 Bing 兵 , Wu 吴 Dejin 德金 , Ning 宁 Zongjun 宗军 , Zhou 周 Xiaowei 晓伟 , Bale Stuart D. 
Published: November 2024

Abstract
Based on the observations by the Parker Solar Probe (PSP) during its encounter phases of approaching the Sun, I. C. Jebaraj et al. found that fundamental–harmonic (F-H) pairs constitute a majority of interplanetary (IP) type III radio bursts. In the present Letter, spectral characteristics of the IP F-H pairs are identified and analyzed further. The observations were made with the Radio Frequency Spectrometer (RFS) experiment on the PSP spacecraft in its encounter phase from the first to the ninth orbit as it traveled from 0.17 to 0.074 au from the Sun. The result shows that the occurrence rate of F-H pairs rises significantly with the rise in the number of IP type III radio bursts detected by the PSP or the enhancement in the time resolution of the RFS instrument. In particular, we compare the relationship between F and H spectral characteristics, such as the frequency-drift rate, emission intensity, relative bandwidth, duration, and fine structure. The results will be helpful for us to understand the physics underlying the generation and evolution of the IP F-H pairs as well as other IP type III radio bursts.
Description préliminaire de la séquence céramique de la région de Nachtigal amont (sud Cameroun)
Authors: Saulieu Geoffroy de , Nlend Pascal Nlend , Ngouoh François , Sokona Bissaï , Abanda Louis Minegue 
Published: November 2024

Le suivi du volet d’archéologie préventive du chantier de barrage hydroélectrique de Nachtigal amont s’est déroulé en deux phases, de 2019 à 2023, grâce à deux contrats gérés par l’IRD et réalisés par une équipe franco-camerounaise. Ces prestations ont permis de récolter plus de 75 148 tessons de poterie sur un peu plus de 200 sites. Une quarantaine de datations radiocarbones au spectromètre de masse par accélérateur ont été réalisées. La description typochronologique préliminaire que nous proposons est fondée sur l’examen d’environ 20 000 fragments provenant de 58 sites archéologiques. Il semble que la séquence se compose de sept groupes différents reconnus surtout par rapport aux critères morphologiques-décoratifs : groupe I (ixe-viie siècle avant notre ère), groupe IIa (viiie-ve siècle avant notre ère), groupe IIb (vie-iie siècle avant notre ère), groupe III (iie siècle avant notre ère-ve siècle de notre ère), groupe IV (xiie-xive siècle de notre ère), groupe V (xve-xviie siècle de notre ère) et groupe VI (xviie siècle de notre ère-époque contemporaine).
Les maisons de chefferie du Mbam (Cameroun)
Authors: Seignobos Christian , Bomono Henri Yambéné 
Published: November 2024

Les maisons de chefferie du Mbam, architectures datées – 1920 jusqu’à fin 1930 –, sont nées de la volonté de l’administration coloniale, qui cherchait à renforcer le pouvoir des chefs qu’elle avait nommés dans des sociétés qui en étaient dépourvues au sens où elle l’entendait. Il s’agit de bâtiments à l’image des demeures coloniales du début du xxe siècle : un étage, entouré d’une véranda généralement portée par des arcades ou des piliers de briques. L’accès à l’étage se fait par un escalier qui se veut monumental. Ces constructions ont, par ailleurs, permis d’initier des corps de métier qui influenceront l’ensemble des architectures locales. La présence de ces demeures désigne aujourd’hui des lieux de pouvoir. Sur ces sites, des ayants droit cherchent à construire au plus près de ces maisons ou de ce qu’il en reste pour signifier leur apparentement avec les chefs défunts et, partant, leur niveau de prétention à la chefferie ou à des représentations locales voire nationales de leur communauté.
Tahirou Husseini, dernier teinturier actif du Nord Bénin
Authors: Gosselain Olivier P. , Mardjoua Barpougouni 
Published: November 2024

En mars 2023, nous avons pu observer et interroger le dernier teinturier en activité du Nord Bénin, dans un quartier de la ville de Nikki. Trésor humain vivant dont la disparition pourrait signifier celle d’une tradition technique vieille de plusieurs siècles, Tahirou Husseini a réalisé devant nous plusieurs opérations relatives à la préparation du bain de teinture et à la coloration des textiles. Il nous a également décrit le contexte dans lequel se pratiquait le métier par le passé et les changements qui se sont opérés au fil du temps. Dans cet article, nous partageons ces informations. Certaines ont rarement été évoquées dans la littérature.