bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Dynamical Constraints on the Masses of the Central Black Holes in Nearby Low-mass Early-type Galactic Nuclei and the First Black Hole Determination for NGC 205
Authors: Nguyen Dieu D. , Seth Anil C. , Neumayer Nadine , Iguchi Satoru , Cappellari Michelle , Strader Jay , Chomiuk Laura , Tremou Evangelia , Pacucci Fabio , Nakanishi Kouichiro , Bahramian Arash , Nguyen Phuong M. , den Brok Mark , Ahn Christopher C. , Voggel Karina T. , Kacharov Nikolay , Tsukui Takafumi , Ly Cuc K. , Dumont Antoine , Pechetti Renuka 
Published: February 2019

Abstract
We improve the dynamical black hole (BH) mass estimates in three nearby low-mass early-type galaxies: NGC 205, NGC 5102, and NGC 5206. We use new Hubble Space Telescope (HST)/STIS spectroscopy to fit the star formation histories of the nuclei in these galaxies, and use these measurements to create local color–mass-to-light ratio (M/L) relations. We then create new mass models from HST imaging and combined with adaptive optics kinematics, we use Jeans dynamical models to constrain their BH masses. The masses of the central BHs in NGC 5102 and NGC 5206 are both below one million solar masses and are consistent with our previous estimates,

M
⊙ and

M
⊙ (3σ errors), respectively. However, for NGC 205, the improved models suggest the presence of a BH for the first time, with a best-fit mass of

M
⊙ (3σ errors). This is the least massive central BH mass in a galaxy detected using any method. We discuss the possible systematic errors of this measurement in detail. Using this BH mass, the existing upper limits of both X-ray, and radio emissions in the nucleus of NGC 205 suggest an accretion rate ≲10−5 of the Eddington rate. We also discuss the color–M/L
eff relations in our nuclei and find that the slopes of these vary significantly between nuclei. Nuclei with significant young stellar populations have steeper color–M/L
eff relations than some previously published galaxy color–M/L
eff relations.
Influence of Nuclear Reaction Rate Uncertainties on Neutron Star Properties Extracted from X-Ray Burst Model–Observation Comparisons
Authors: Meisel Zach , Merz Grant , Medvid Sophia 
Published: February 2019

Abstract
Type-I X-ray bursts can be used to determine properties of accreting neutron stars via comparisons between model calculations and astronomical observations, exploiting the sensitivity of models to astrophysical conditions. However, the sensitivity of models to nuclear physics uncertainties calls into question the fidelity of constraints derived in this way. Using X-ray burst model calculations performed with the code MESA, we investigate the impact of uncertainties for nuclear reaction rates previously identified as influential and compare them to the impact of changes in astrophysical conditions, using the conditions that are thought to best reproduce the source GS 1826-24 as a baseline. We find that reaction rate uncertainties are unlikely to significantly change conclusions about the properties of accretion onto the neutron star surface for this source. However, we find that reaction rate uncertainties significantly hinder the possibility of extracting the neutron star mass–radius ratio by matching the modeled and observed light curves, due to the influence of reaction rates on the modeled light curve shape. Particularly influential nuclear reaction rates are 15O(α, γ) and 23Al(p, γ), though other notable impacts arise from 14O(α, p), 18Ne(α, p),

, 24Mg(α, γ),

, and 61Ga(p, γ). Furthermore, we find that varying some nuclear reaction rates within their uncertainties has an impact on the neutron star crust composition and thermal structure that is comparable to relatively significant changes to the accretion conditions.
Revealing Reionization with the Thermal History of the Intergalactic Medium: New Constraints from the Lyα Flux Power Spectrum
Authors: Boera Elisa , Becker George D. , Bolton James S. , Nasir Fahad 
Published: February 2019

Abstract
We present a new investigation of the thermal history of the intergalactic medium (IGM) during and after reionization using the Lyα forest flux power spectrum at 4.0 ≲ z ≲ 5.2. Using a sample of 15 high-resolution spectra, we measure the flux power down to the smallest scales ever probed at these redshifts (−1 ≲ log(k/km−1 s) ≲ −0.7). These scales are highly sensitive to both the instantaneous temperature of the IGM and the total energy injected per unit mass during and after reionization. We measure temperatures at the mean density of T
0 ∼ 7000–8000 K, consistent with no significant temperature evolution for redshifts 4.2 ≲ z ≲ 5.0. We also present the first observational constraints on the integrated IGM thermal history, finding that the total energy input per unit mass increases from u
0 ∼ 4.6 to 7.3 eV

from z ∼ 6 to 4.2 assuming a ΛCDM cosmology. We show how these results can be used simultaneously to obtain information on the timing and the sources of the reionization process. Our first proof of concept using simplistic models of instantaneous reionization produces results comparable to and consistent with the recent Planck constraints, favoring models with

.
Temperature Structure in the Inner Regions of Protoplanetary Disks: Inefficient Accretion Heating Controlled by Nonideal Magnetohydrodynamics
Authors: Mori Shoji , Bai Xue-Ning , Okuzumi Satoshi 
Published: February 2019

Abstract
The gas temperature in protoplanetary disks (PPDs) is determined by a combination of irradiation heating and accretion heating, with the latter conventionally attributed to turbulent dissipation. However, recent studies have suggested that the inner disk (a few au) is largely laminar, with accretion primarily driven by magnetized disk winds, as a result of nonideal magnetohydrodynamic (MHD) effects from weakly ionized gas, suggesting an alternative heating mechanism by Joule dissipation. We perform local stratified MHD simulations including all three nonideal MHD effects (ohmic, Hall, and ambipolar diffusion) and investigate the role of Joule heating and the resulting disk vertical temperature profiles. We find that in the inner disk, as ohmic and ambipolar diffusion strongly suppress electrical current around the midplane, Joule heating primarily occurs at several scale heights above the midplane, making the midplane temperature much lower than that with the conventional viscous heating model. Including the Hall effect, Joule heating is enhanced/reduced when the magnetic fields threading the disks are aligned/anti-aligned with the disk rotation, but it is overall ineffective. Our results further suggest that the midplane temperature in the inner PPDs is almost entirely determined by irradiation heating, unless viscous heating can trigger thermal ionization in the disk innermost region to self-sustain magnetorotational instability turbulence.
Polluted White Dwarfs: Mixing Regions and Diffusion Timescales
Authors: Bauer Evan B. , Bildsten Lars 
Published: February 2019

Abstract
Many isolated white dwarfs (WDs) show spectral evidence of atmospheric metal pollution. Since heavy-element sedimentation timescales are short, this most likely indicates ongoing accretion. Accreted metals encounter a variety of mixing processes at the WD surface: convection, gravitational sedimentation, overshoot, and thermohaline instability. We present MESA WD models that explore each of these processes and their implications for inferred accretion rates. We provide diffusion timescales for many individual metals, and we quantify the regimes in which thermohaline mixing dominates over gravitational sedimentation in setting the effective settling rate of the heavy elements. We build upon and confirm earlier work finding that accretion rates as high as

are needed to explain the observed pollution in DA WDs for T
eff > 15,000 K, and we provide tabulated results from our models that enable accretion rate inferences from observations of polluted DA WDs. If these rates are representative of young WDs, we estimate that the total mass of planetesimal material accreted over a WD lifetime may be as high as

, though this estimate is susceptible to potential selection biases and uncertainties about the nature of disk processes that supply accretion to the WD surface. We also find that polluted DB WDs experience much less thermohaline mixing than DA WDs, and we do not expect thermohaline instability to be active for polluted DB WDs with

.
Merging Cluster Collaboration: Optical and Spectroscopic Survey of a Radio-selected Sample of 29 Merging Galaxy Clusters
Authors: Golovich N. , Dawson W. A. , Wittman D. M. , Jee M. J. , Benson B. , Lemaux B. C. , van Weeren R. J. , Andrade-Santos F. , Sobral D. , de Gasperin F. , Brüggen M. , Bradač M. , Finner K. , Peter A. 
Published: February 2019

Abstract
Multi-band photometric and multi-object spectroscopic surveys of merging galaxy clusters allow for the characterization of the distributions of constituent DM and galaxy populations, constraints on the dynamics of the merging subclusters, and an understanding of galaxy evolution of member galaxies. We present deep photometric observations from Subaru/SuprimeCam and a catalog of 4431 spectroscopic galaxies from Keck/DEIMOS observations of 29 merging galaxy clusters ranging in redshift from z = 0.07 to 0.55. The ensemble is compiled based on the presence of radio relics, which highlight cluster-scale collisionless shocks in the intracluster medium. Together with the spectroscopic and photometric information, the velocities, timescales, and geometries of the respective merging events may be tightly constrained. In this preliminary analysis, the velocity distributions of 28 of the 29 clusters are shown to be well fit by single Gaussians. This indicates that radio-relic mergers largely occur transverse to the line of sight and/or near-apocenter. In this paper, we present our optical and spectroscopic surveys, preliminary results, and a discussion of the value of radio-relic mergers for developing accurate dynamical models of each system.
Comparing Treatments of Weak Reactions with Nuclei in Simulations of Core-collapse Supernovae
Authors: Nagakura Hiroki , Furusawa Shun , Togashi Hajime , Richers Sherwood , Sumiyoshi Kohsuke , Yamada Shoichi 
Published: February 2019

Abstract
We perform an extensive study of the influence of nuclear weak interactions on core-collapse supernovae, paying particular attention to consistency between nuclear abundances in the equation of state (EOS) and nuclear weak interactions. We compute properties of uniform matter based on the variational method. For inhomogeneous nuclear matter, we take a full ensemble of nuclei into account with various finite-density and thermal effects and directly use the nuclear abundances to compute nuclear weak interaction rates. To quantify the impact of a consistent treatment of nuclear abundances on CCSN dynamics, we carry out spherically symmetric CCSN simulations with full Boltzmann neutrino transport, systematically changing the treatment of weak interactions, EOSs, and progenitor models. We find that the inconsistent treatment of nuclear abundances between the EOS and weak interaction rates weakens the EOS dependence of both the dynamics and neutrino signals. We also test the validity of two artificial prescriptions for weak interactions of light nuclei and find that both prescriptions affect the dynamics. Furthermore, there are differences in neutrino luminosities by ∼10% and in average neutrino energies by 0.25–1 MeV from those of the fiducial model. We also find that the neutronization burst neutrino signal depends on the progenitor more strongly than on the EOS, preventing a detection of this signal from constraining the EOS.
The Spectral Properties of the Bright Fast Radio Burst Population
Authors: Macquart J.-P. , Shannon R. M. , Bannister K. W. , James C. W. , Ekers R. D. , Bunton J. D. 
Published: February 2019

Abstract
We examine the spectra of 23 fast radio bursts (FRBs) detected in a fly’s-eye survey with the Australian SKA Pathfinder, including those of three bursts not previously reported. The mean spectral index of

(F

ν
∝ ν

α
) is close to that of the Galactic pulsar population. The sample is dominated by bursts exhibiting a large degree of spectral modulation: 17 exhibit fine-scale spectral modulation with an rms exceeding 50% of the mean, with decorrelation bandwidths (half-maximum) ranging from ≈1 to 49 MHz. Most decorrelation bandwidths are an order of magnitude lower than the ≳30 MHz expected of Galactic interstellar scintillation at the Galactic latitude of the survey,

. However, these bandwidths are consistent with the ∼ν
4 scaling expected of diffractive scintillation when compared against the spectral structure observed in bright UTMOST FRBs detected at 843 MHz. A test of the amplitude distribution of the spectral fluctuations reveals only 12 bursts consistent at better than a 5% confidence level with the prediction of 100%-modulated diffractive scintillation. Five of six FRBs with a signal-to-noise ratio exceeding 20 are only consistent with this prediction at less than 1% confidence. Nonetheless, there is weak evidence (92%–94% confidence) of an anti-correlation between the amplitude of the spectral modulation and dispersion measure (DM), which suggests that it originates as a propagation effect. This effect is corroborated by the smoothness of the higher-DM Parkes FRBs, and could arise due to quenching of diffractive scintillation (e.g., in the interstellar medium of the host galaxy) by angular broadening in the intergalactic medium.
The Simultaneous Formation of Cored, Tangentially Biased, and Kinematically Decoupled Centers in Massive Early-type Galaxies
Authors: Rantala Antti , Johansson Peter H. , Naab Thorsten , Thomas Jens , Frigo Matteo 
Published: February 2019

Abstract
We study the impact of merging supermassive black holes (SMBHs) on the central regions of massive early-type galaxies (ETGs) using a series of merger simulations with varying mass ratios. The ETG models include realistic stellar and dark matter components and are evolved with the gadget-3 based regularized tree code ketju. We show that observed key properties of the nuclear stellar populations of massive ETGs, namely flat stellar density distributions (cores), tangentially biased velocity distributions, and kinematically decoupled (counter-)rotation, can naturally result from a single process—the scouring by SMBHs. Major mergers with mass ratios of q > 1/3 produce flat, tangentially biased cores with kinematically distinct components. These kinematic features originate from reversals of the SMBH orbits caused by gravitational torques after pericenter passages. Minor mergers (q ≲ 1/3), on the other hand, form non-rotating cores and the orbit reversal becomes less important. Low-density stellar cores scoured in (multiple) minor mergers are less tangentially biased. This implies that the nuclear stellar properties of massive ETGs can be solely explained by stellar dynamical processes during their final assembly without any need for “feedback” from accreting black holes. We predict a strong correlation between decoupled cores, central anisotropy, and merger history: decoupled cores form in binary mergers and we predict them to occur in elliptical galaxies with the strongest central anisotropy. Measurements of the central orbital structure are the key to understanding the number of mergers that a given galaxy has experienced.
Towards a general theory of social and economic development: Evolution of coordination mechanisms
Authors: Polterovich Victor 
Published: February 2019

A new approach to understanding social and economic development is proposed, based on consideration of the evolution of coordination mechanisms. The work consists of two parts. In the first part, a critical analysis of four recently proposed theories of social development, focusing on geographical, institutional or cultural factors, is given. These theories have greatly enriched our understanding of the evolution of society, however, as analysis shows, none of them provides a satisfactory description of the driving forces and mechanisms of this evolution; the main reason is rooted in their common deficiency — monocausality. It is proposed to distinguish between two types of development, catching up and leading. The basic ideas of the theory of catching up development are presented. This approach makes it possible to explain the phenomenon of the “economic miracle” as a result of mutually conditioned changes in culture, institutions, technological progress and well-being in the context of interaction of competition, power and collaboration mechanisms.
The second part is devoted to the theory of leading socioeconomic development. It is shown how in Western Europe, as a result of the interaction of the above four factors, specific forms and combinations of the three main mechanisms of coordination — competition, power and collaboration — emerged at each stage of evolution. I emphasize the importance of ideology and the phenomenon of technical progress in the formation of institutions of economic and political competition that contributed to the creation of the welfare state. These changes and economic growth created the conditions for further transformation of civil culture: increasing levels of trust, tolerance, altruism and cosmopolitanism, expanding the planning horizon. The decrease in the level of coercion built into the mechanisms of power and competition are demonstrated as well as the expansion of the role of collaboration. A hypothesis is advanced that the speed of this process depends on geographical factors. The idea of the welfare world is discussed.
An Effective Approach for Clickbait Detection Based on Supervised Machine Learning Technique
Authors: Daoud Daoud M. , Abou El-Seoud Samir 
Published: February 2019

Clickbait is a term used to describe a deceiving web content that uses ambiguity to prompt the user into clicking a link. It aims to increase the number of online readers in order to generate more advertising revenue. In other words, Clickbait is used to describe a type of hyperlink on a web page which seduces a user to click a link to continue reading a specific article.Typically such links will forward the visitor to a page that requires payment, registration, or lead a user to a site, which tries to sell user something or possibly extort user, by withholding the promised "bait". We use supervised machine learning to create a model that is trained on 24 features. This method achieved an F1-score of 79% and an area under the ROC curve of 0.7. Our methodology emphasises the importance of using features extracted from different elements of social media posts along with features that are extracted from the title and the article. In this research, we show that it is possible to identify Clickbaits using all parts of the post while keeping the number of features as minimum as possible.
A performance management model addressing human factors in the North West provincial administration
Authors: Klinck Kezell , Swanepoel Sonia 
Published: February 2019

Orientation: The article investigated factors from several perspectives using human resources-related issues of governance, legislation, regulation, organisation, administration and communication, workplace sociology variables pertaining to social and psychological relationships and several other factors that have an impact on the complex matrix of determinants for performance improvement in the public service.Research purpose: This article explored the human factors linked to the performance management (PM) processes and its impact on the effectiveness of service delivery in the North West provincial administration (NWPA). The article isolated the strengths and weaknesses of the system of performance assessment from the human relations perspective, technical usage, the structural–organisational and the strategic perspectives, uniformity, legislative compliance and other possibilities envisaged and emerging.Motivation for the study: The study would deliver a successful and carefully crafted PM model that could be used to remedy the current performance situation through improved and effective communication channels, as well as ongoing feedback, leading to a more productive and motivated workforce. This would ultimately yield improved service delivery for the citizens of the North West Province.Research approach/design and method: To answer the main research questions, sub-questions and objectives of this study, several participants (permanent employees and managers) found in the departments within the NWPA had to respond to diverse instruments of inquiry (questionnaires, interview schedules, expert, operational, strategic and grass-roots opinion, etc.). The study took a sequential mixed-methods approach where interpretivist (qualitative) and positivist (quantitative) approaches were applied as the philosophy and descriptive statistics were used.Main findings: The main findings highlighted all the human factors that mitigated against performance improvement in the NWPA. From the evidence gathered, some departments exhibited problematic manager–subordinate relationships, lack of training, no proper feedback, low staff morale leading to low job satisfaction, lack of leadership as well as broken channels of communication.Practical/managerial implications: The findings revealed that it is important for the NWPA management to undertake the necessary efforts in order to adapt a new strategy and comprehensive model for improved performance, which would ultimately lead towards efficient and effective service delivery in the North West Province.Contribution/value-add: This paper explores the salient human factors to be taken into consideration during performance management in the North West Provincial Administration.