Binary Configurations Research Articles

Decomposition of galactic X-ray emission with PHOX

Context.X-ray observations of galaxies with high spatial resolution instruments such asChandrahave revealed that major contributions to their diffuse emission originate from X-ray-bright point sources in the galactic stellar field. It has been established that these point sources, called X-ray binaries, are accreting compact objects with stellar donors in a binary configuration. They are classified according to the predominant accretion process: wind-fed in the case of high-mass donors and Roche-lobe mass transfer in the case of low-mass donors. Observationally, it is challenging to reliably disentangle these two populations from each other because of their similar spectra.Aims.We provide a numerical framework with which spatially and spectrally accurate representations of X-ray binary populations can be studied from hydrodynamical cosmological simulations. We construct average spectra, accounting for a hot gas component, and verify the emergence of observed scaling relations between galaxy-wide X-ray luminosity (LX) and stellar mass (M*) and betweenLXand the star-formation rate (SFR).Methods.Using simulated galaxy halos extracted from the (48 h−1 cMpc)3volume of the Magneticum Pathfinder cosmological simulations atz = 0.07, we generate mock spectra with the X-ray photon-simulator PHOX. We extend the PHOXcode to account for the stellar component in the simulation and study the resulting contribution in composite galactic spectra.Results.Well-known X-ray binary scaling relations with galactic SFR andM*emerge self-consistently, verifying our numerical approach. Average X-ray luminosity functions are perfectly reproduced up to the one-photon luminosity limit. Comparing our resultingLX − SFR − M*relation for X-ray binaries with recent observations of field galaxies in the Virgo galaxy cluster, we find significant overlap. Invoking a metallicity-dependent model for high-mass X-ray binaries yields an anticorrelation between mass-weighted stellar metallicity and SFR-normalized luminosity. The spatial distribution of high-mass X-ray binaries coincides with star-formation regions of simulated galaxies, while low-mass X-ray binaries follow the stellar mass surface density. X-ray binary emission is the dominant contribution in the hard X-ray band (2–10 keV) in the absence of an actively accreting central super-massive black hole, and it provides a ∼50% contribution in the soft X-ray band (0.5–2 keV), rivaling the hot gas component.Conclusions.We conclude that our modeling remains consistent with observations despite the uncertainties connected to our approach. The predictive power and easily extendable framework hold great value for future investigations of galactic X-ray spectra.

New approach to the compound energy formalism (NACEF) part I. Thermodynamic modeling based on the sublattice model

In the CALPHAD modeling, the Compound Energy Formalism (CEF) is widely used because it is a general formalism which allows to select the most appropriate model for different kind of phases (gas phase, solid and liquid solutions, interstitial solutions, intermetallic compounds, solid oxide phases, ionic melts, phases that show chemical order-disorder transformations …). It consists in dividing the phase into sublattices and the models differ by the nature of the constituents (atoms, ions, vacancies, etc.) present in the different considered sublattices where mixing may or may not occur. For many intermetallic compounds which present a crystal structure containing many crystallographic sites on which disorder occurs, the number of parameters to be evaluated which varies exponentially with the number of sublattices becomes a problem in multicomponent systems. This yields the necessity to simplify the description and reduce the number of sublattices by combining different sites in single sublattices and this leads to that different simplifications can be used to model a phase in different systems. It is quite known that the CEF approach does not allow continuous compatibility between the different simplifications which constitutes a problem for the development of multicomponent databases.In the present paper, we present a New Approach to the Compound Energy Formalism (NACEF) which is derived mathematically from the CEF and therefore retains its full potential while providing several important improvements. As example, considering the particular case of the complex σ phase, the present work shows that NACEF makes it possible to make compatible a model based on the full description (five-sublattice model) with simplifications which can be made of it. On the other hand, it is also shown that NACEF form combined to a simple Muggianu type extrapolation allows to obtain reliable estimates of the energies of ordered configurations in multicomponent systems using those for the binary configurations obtained from DFT calculations.

Discovery of a Binary-origin Classical Cepheid in a Binary System with a 59 day Orbital Period* *Based on observations collected at the European Southern Observatory, Chile. † †This Letter includes data gathered with the 6.5 m Magellan Clay Telescope at Las Campanas Observatory, Chile.

We report the discovery of a surprising binary configuration of the double-mode Cepheid OGLE-LMC-CEP-1347 pulsating in the first (P 1 = 0.690 days) and second-overtone (P 2 = 0.556 days) modes. The orbital period (P orb = 59 days) of the system is five times shorter than the shortest known to date (310 days) for a binary Cepheid. The Cepheid itself is also the shortest-period one ever found in a binary system and the first double-mode Cepheid in a spectroscopically double-lined binary. OGLE-LMC-CEP-1347 is most probably on its first crossing through the instability strip, as inferred from both its short period and fast period increase, consistent with evolutionary models, and from the short orbital period (not expected for binary Cepheids whose components have passed through the red giant phase). Our evolutionary analysis yielded a first-crossing Cepheid with a mass in a range of 2.9–3.4 M ⊙ (lower than any measured Cepheid mass), consistent with observations. The companion is a stable star, at least two times fainter and less massive than the Cepheid (preliminary mass ratio q = 0.55), while also redder and thus at the subgiant or more advanced evolutionary stage. To match these characteristics, the Cepheid has to be a product of binary interaction, most likely a merger of two less massive stars, which makes it the second known classical Cepheid of binary origin. Moreover, further evolution of the components may lead to another binary interaction.

Forming hot subluminous stars from hierarchical triples – I. The role of an outer tertiary on formation channels

ABSTRACT We present evolutionary pathways for creating hot subdwarf OB (sdOB) stars from hierarchical triple configurations. We use the population synthesis code Multiple Stellar Evolution to follow the stellar, binary, and gravitational dynamical evolution of triple-star systems. To ascertain the effect of the outer tertiary, we also consider the evolution of the inner binary with the tertiary component removed. We find we are able to create sdOB stars in single, binary, and triple configurations. We also demonstrate that it is possible to form sdOBs in systems that undergo triple common envelope evolution, when the tertiary star undergoes unstable mass transfer on to the inner binary. We are unable to create single or wide sdOB systems without involving a merger earlier in the evolution. The triples can produce sdOBs in binaries with wide, non-interacting companions through binary interactions, which is impossible in isolated binaries. Owing to the closeness of the inner binary in hierarchical triples the formation channels associated with stable mass transfer are suppressed when compared to the isolated binary case.

Charged and rotating multi-black holes in an external gravitational field

We construct analytical and regular solutions in four-dimensional General Relativity which represent multi-black hole systems immersed in external gravitational field configurations. The external field background is composed by an infinite multipolar expansion, which allows to regularise the conical singularities of an array of collinear static black holes. A stationary rotating generalisation is achieved by adding independent angular momenta and NUT parameters to each source of the binary configuration. Moreover, a charged extension of the binary black hole system at equilibrium is generated. Finally, we show that the binary Majumdar–Papapetrou solution is consistently recovered in the vanishing external field limit. All of these solutions reach an equilibrium state due to the external gravitational field only, avoiding in this way the presence of any string or strut defect.

DRaNN_PSO: A deep random neural network with particle swarm optimization for intrusion detection in the industrial internet of things

The Industrial Internet of Things (IIoT) is a rapidly emerging technology that increases the efficiency and productivity of industrial environments by integrating smart sensors and devices with the internet. The advancements in communication technologies have introduced stable connectivity and a higher data transfer rate in the IIoT. The IIoT devices generate a massive amount of information that requires intelligent data processing techniques for the development of cybersecurity mechanisms. In this regard, deep learning (DL) can be an appropriate choice. This paper proposes a Deep Random Neural Network (DRaNN) based fast and reliable attack detection scheme for IIoT environments. The RaNN is an advanced variant of the traditional Artificial Neural Network (ANN) with a highly distributed nature and better generalization capabilities. To attain a higher attack detection accuracy, the proposed RaNN is optimally trained by incorporating hybrid particle swarm optimization (PSO) with sequential quadratic programming (SQP). The SQP-enabled PSO facilitates the neural network to select optimal hyperparameters. The efficacy of the suggested scheme is analyzed in both binary and multiclass configurations by conducting extensive experiments on three new IIoT datasets. The experimental outcomes demonstrates the promising performance of the proposed design for all datasets.

Operation of a 4-bit RSFQ digital-to-analog converter based on a binary split-confluence configuration

One of the unique applications of single-flux-quantum (SFQ) circuitry is a digital-to-analog converter (DAC) of which the output voltage is defined by the Josephson effect. Recently, we have designed and operated rapid single-flux-quantum (RSFQ) DACs with frequency modulation of SFQ pulse sequences. In this paper, we report our design and test results of a 4-bit RSFQ-DAC based on the configuration of the “sum of selected bits sequence (Σ-SBS)”. By adjusting the timing margins, in addition to the fabrication using the Nb integration process with the critical current density as high as 10 kA/cm2, the maximum output voltage up to 260 μV was demonstrated.

Neural network flows of low q-state Potts and clock models

It is known that a trained restricted Boltzmann machine (RBM) on the binary Monte Carlo Ising spin configurations, generates a series of iterative reconstructed spin configurations which spontaneously flow and stabilize to the critical point of physical system. Here we construct a variety of neural network (NN) flows using the RBM and (variational) autoencoders, to study the q-state Potts and clock models on the square lattice for q = 2, 3, 4. The NN are trained on Monte Carlo spin configurations at various temperatures. We find that the trained NN flow does develop a stable point that coincides with critical point of the q-state spin models. The behavior of the NN flow is nontrivial and generative, since the training is unsupervised and without any prior knowledge about the critical point and the Hamiltonian of the underlying spin model. Moreover, we find that the convergence of the flow is independent of the types of NNs and spin models, hinting a universal behavior. Our results strengthen the potential applicability of the notion of the NN flow in studying various states of matter and offer additional evidence on the connection with the renormalization group flow.

Measuring the mass of the black widow PSR J1555-2908

ABSTRACT Accurate measurements of the masses of neutron stars are necessary to test binary evolution models, and to constrain the neutron star equation of state. In pulsar binaries with no measurable post-Keplerian parameters, this requires an accurate estimate of the binary system’s inclination and the radial velocity of the companion star by other means than pulsar timing. In this paper, we present the results of a new method for measuring this radial velocity using the binary synthesis code Icarus. This method relies on constructing a model spectrum of a tidally distorted, irradiated star as viewed for a given binary configuration. This method is applied to optical spectra of the newly discovered black widow PSR J1555–2908. By modeling the optical spectroscopy alongside optical photometry, we find that the radial velocity of the companion star is 397 ± 4 km s−1 (errors quoted at 95 per cent confidence interval), as well as a binary inclination of >75°. Combined with γ-ray pulsation timing information, this gives a neutron star mass of 1.67$^{+0.15}_{-0.09}$ M⊙ and a companion mass of 0.060$^{+0.005}_{-0.003}$ M⊙, placing PSR J1555–2908 at the observed upper limit of what is considered a black widow system.

Equatorially symmetric configurations of two Kerr-Newman black holes

In this paper, we employ the general equatorially symmetric two-soliton solution of the Einstein-Maxwell equations for elaborating two physically meaningful configurations describing a pair of equal Kerr-Newman corotating black holes separated by a massless strut. The first configuration is characterized by opposite magnetic charges of its constituents, while in the second configuration the black holes carry equal electric and opposite magnetic charges, thus providing a nontrivial example of a binary dyonic black-hole system. The thermodynamic properties of these binary configurations are studied and the first law of thermodynamics taking correctly into account the magnetic field contribution is formulated for each case.

Container Technologies for ARM Architecture: A Comprehensive Survey of the State-of-the-Art

Container technology is becoming increasingly popular as an alternative to traditional virtual machines because it provides a faster, lighter, and more portable runtime environment for the applications. A container bundles the application and its binary code, libraries, and configuration files together while sharing the host operating system image. Accordingly, containers efficiently share resources and operate small micro-services, software programs, and even more extensive applications with less overhead than virtual machines. There are many container technologies available with Docker being the most popular and many technologies support multiple architectures, including the ARM architecture. Due to its energy efficiency and high-performance, which are crucial parameters in containerization, ARM architecture is becoming prevalent in container technologies. In this paper, we explore various container technologies that support ARM architecture and investigate the pros and cons of each technology. Moreover, we provide a comparative analysis of both container orchestrators and container runtimes that are most prominent competitors of Docker. We also consider security of container technologies with particular focus on the image scanning tools that supports ARM architecture. Our survey reveals that ARM technology is gaining popularity in containerization and almost all recent technologies support ARM architecture.

Can We Prescribe the Physical Parameters of Multiple Black Holes?

The parabolic-hyperbolic form of the constraints and superposed Kerr-Schild black holes have already been used to provide a radically new initialization of binary black hole configurations. The method generalizes straightforwardly to multiple black hole systems. This paper is to verify that each of the global Arnowitt-Deser-Misner quantities of the constructed multiple black hole initial data can always be prescribed, as desired, in advance of solving the constraints. These global charges are shown to be uniquely determined by the physical parameters of the involved individual Kerr-Schild black holes.

Unraveling the Mystery of Ternary Organic Solar Cells: A Review on the Influence of Third Component on Structure–Morphology–Performance Relationships

The addition of a third component to a binary bulk heterojunction configuration in organic solar cells is called ternary organic solar cells (TOSCs), which is trending as a solar cell configuration that strikes balance between tandem and binary bulk heterojunction organic solar cells by increasing spectral absorption without laborious processing methods. Apart from increasing the spectral range, the third component is also able to tune the morphology and electronic properties for enhanced performance. Existing reviews on TOSCs thus far mainly focus on reporting related research progresses and their respective performances. Instead, a thorough review on understanding the influence of the third component in terms of morphology and electronic properties via a computational chemistry perspective (structure–morphology–performance) is presented here. This bottom‐up approach reviews the influence of the third component originating from intermolecular interactions to crystallization and phase properties, and finally to electronic properties such as charge transfer and energy transfer. Herein, new theoretical insights opening up potential research opportunities to propel organic solar cells to one day surpass 20% power conversion efficiency are revealed.

Calamitic-Type Dipolar and Quadrupolar Chromophores with a Twisted Peripheral Handle: Structure–Property Outlook as Nonfullerene Acceptors for Binary Solar Cells

Symmetrical (14, 15) and unsymmetrical (16, 17) molecules possessing tetracyanobutadiene (TCBD) as a twisted end group on the carbazole/fluorene backbone were synthesized as nonfullerene acceptors (NFAs). Systematic structural correlation of these chromophores on the optoelectronic, electrochemical, and physicochemical properties revealed better acceptor properties for symmetrical (14, 15) compared to unsymmetrical analogues (16, 17). High molar absorptivity, deep HOMO–LUMOs, better electron-accepting capacity, along with other complementary molecular properties are some of the associated factors for the better acceptor character. In a binary solar cell configuration blended with P3HT donor, quadrupolar-type symmetrical chromophores (14, 15) displayed higher power conversion efficiencies over dipolar-type unsymmetrical chromophores (16, 17). In particular, 14 with an efficiency of 5.37% emerged as the best candidate with further enhancement to 6.30% upon additive processing. The dependence of processing on the improved photoinduced current was attributed to the better nanoscale morphology, crystallinity, and electron mobility. In terms of efficiency, it is the third highest for any TCBD-based NFA solar cells. Overall, this work validates the impact of a nonplanar TCBD auxiliary positioned within a calamitic-type π-framework to realize alternative NFAs. Viewed from a fundamental perspective, the initial results are promising, and further fine tuning of the molecular structure could possibly form an ideal acceptor for organic photovoltaics.

Turbulence and its connection to episodic accretion in binary YSOs

ABSTRACT We report signatures of episodic accretion in young stellar objects (YSOs) that emerge in protobinary configurations in a gravoturbulent gas collapse. We find in most of these protobinary systems strong accretion bursts between the two companions with a recurrence time-scale of about 1 kyr. The accretion rate on to the secondary star typically exceeds that on to the primary with a peak value of 2 × 10−2 M⊙ yr−1 for the former and 6 × 10−3 M⊙ yr−1 for the latter. We propose that the secondary companion, which remains more active in its episodes of accretion bursts, especially for the gas cores with subsonic velocity dispersion, may provide observational opportunities to find traces of episodic accretion in the surrounding gas of the embedded YSOs that are in a binary configuration. Also, protostars evolving as single objects in the same environment show fewer accretion bursts and all together a more steady mass growth history. The prestellar cores with subsonic velocity dispersion exhibit an order of magnitude more intense accretion bursts than in the case of cores with supersonic velocity dispersions. The latter shows the formation of some of the protobinaries in which the primary acts as a more actively accreting companion. This can support these binaries to become systems of extreme mass ratio. Moreover, the YSOs in binary configurations with small semimajor axis a ≈ 50 au and high mass ratio q > 0.7 support phases of intense episodic accretion. The eccentricity, however, seems to play no significant role in the occurrence of accretion bursts.

Characterizing Undetected Stellar Companions with Combined Data Sets

Abstract Binaries play a critical role in the formation, evolution, and fundamental properties of planets, stars, and stellar associations. Observational studies in these areas often include a mix of observations aimed at detecting or ruling out the presence of stellar companions. Rarely can nondetections rule out all possible binary configurations. Here we present MOLUSC, our framework for constraining the range of properties of unseen companions using astrometric, imaging, and velocity information. We showcase the use of MOLUSC on a number of systems, ruling out stellar false positives in the signals of HIP 67522b and DS Tuc Ab. We also demonstrate how MOLUSC could be used to predict the number of missing companions in a stellar sample using the ZEIT sample of young planet hosts. Although our results are not significant, with a larger sample, MOLUSC could be used to see if close-in planets are less common in young binary systems, as is seen for their older counterparts.

Numerical investigation of the density sorting of grains using water jigging

This paper is devoted to the investigation of the density sorting of grains using water jigging. Experiments achieved in a laboratory scale water jig for two initial binary bed configurations are studied and compared to numerical results. The vertical composition of the deposit is estimated after different number of water pulses to represent the sorting evolution in time. Simulations are based on a multiscale model in which the fluid is solved at a larger scale than the grain diameter using the finite element method, while the grains are considered as rigid bodies and solved using the nonsmooth contact dynamics. Key parameters are numerically varied and observed to determine the sensitivity of the process.

Biomimetic surface strategy of spectrum-tailored liquid metal via blackbody inspiration for highly efficient solar steam generation, desalination, and electricity generation

Solar steam generation as a promising strategy has attracted more and more attention owing to its applications of the water purification which meet the demand of clean water worldwide. Photothermal material, as the key component of solar evaporators, has aroused great interest in the design of extraordinary photothermal conversion efficiency. Herein, liquid metal was the first time used to develop a photothermal promotor with the tailored spectrum via the dipole layer strategy for highly efficient solar steam generation. As the proof-of-concept, cellulose nanocrystals were applied as bonding agent of matrix scaffold and photothermal layer for the successful preparation of the lignin-based aerogel evaporators. Inspired by the seedless sunflower, binary configurations of interior topology and surface topography was manipulated on the layer-doubled lignin-based aerogels with inverted pyramid veneer for the favorable multi-functionalities, which could hardly realize within the entirety before. The blackbody-inspired aerogel evaporators showed exceptional solar evaporation efficiency of 94% under 1 sun, and the depuration and desalination efficiency up to 99% in the sewage (water containing Zn2+, Ni2+, Cu2+, Fe3+) and seawater (Yellow sea, China). In addition, the resulted lignin-based aerogels also presented a promising application in the electricity generation field. This work opens a new avenue to design liquid metals with excellent light absorption ability for the effective solar steam generation, sewage depuration and desalination, with the application of liquid metals in the electricity generation field.

Thermodynamics of two aligned Kerr-Newman black holes

Using the notion of thermodynamic length, the first law of thermodynamics is consistently derived for two binary configurations of equal Kerr-Newman black holes separated by a massless strut. Like in the electrostatic systems of two Reissner-Nordstr\"om black holes and stationary vacuum systems of two Kerr black holes considered earlier, the thermodynamic length $\ell$ turns out to be defined by the same simple formula $\ell=L\exp(\gamma_0)$, $L$ being the coordinate length of the strut and $\gamma_0$ the value of the metric function $\gamma$ on the strut, which permits the elaboration of $\ell$ in a concise analytic form. The expression of the free energy in the case of two generic Kerr-Newman black holes is also proposed.

Stability analysis of the spin evolution fixed points in inspiraling compact binaries with black hole, neutron star, gravastar, or boson star components

Based on the secular spin evolution of black holes, neutron stars, gravastars, or boson stars in precessing compact binaries on eccentric orbit, we identify the aligned and more generic coplanar configurations of the spins and orbital angular momentum as fix points. Through a dynamical system analysis, we investigate their linear stability as function of the mass quadrupole parameter. Marginal stability holds for the binary configurations with both spins antialigned to the orbital angular momentum, for both spins aligned to the orbital angular momentum (with the exception of certain quadrupolar parameter ranges of neutron stars and boson stars), and for the extremal mass ratio. For equal masses, the configurations of one of the spins aligned and the other antialigned is stable for gravastar binaries, for neutron star binaries in the high quadrupolar parameter range, and for boson star binaries. For some unequal mass gravastar binaries, black hole binaries or neutron star binaries, a transition from stability to instability can occur during the inspiral, when one of the spins is aligned, while the other is antialigned to the orbital angular momentum. We discover a transitional instability regime during the inspiral of certain gravastar, neutron star, or boson star binaries with opposing spins. For coplanar configurations we find instabilities only for the gravastar - gravastar, boson star - boson star and black hole - boson star binaries. For a given spin configuration, marginal stability strongly depends on the value of the quadrupolar parameters. The stability region is larger for neutron star binaries than for black hole binaries, while the mixed systems have a restricted stability parameter region.