ShantanuT01/DACTYL-Pretraining huggingface dataset:
We report the novel critical behavior of magnetization in low carrier concentration systems UTeS and USeS that exhibit the large negative magnetoresistance around the ferromagnetic transition temperatures T_C ~ 85 and 23 K, respectively. UTeS and USeS crystallize in the same orthorhombic TiNiSi-type crystal structure as those of uranium ferromagnetic superconductors URhGe and UCoGe. We determine the critical exponents, beta for the spontaneous magnetization M_s, gamma for the magnetic susceptibility chi, and delta for the magnetization isotherm at T_C with several methods. The ferromagnetic states in UTeS and USeS have strong uniaxial magnetic anisotropy. However, the critical exponents in the two compounds are different from those in the three-dimensional Ising model with short-range magnetic exchange interactions. Similar sets of the critical exponents have been reported for the uranium ferromagnetic superconductors UGe_2 and URhGe, and uranium intermetallic ferromagnets URhSi, UIr and U(Co_0.98Os_0.02)Al. The universality class of the ferromagnetic transitions in UTeS and USeS may belong to the same one for the uranium compounds. The novel critical phenomenon associated with the ferromagnetic transition is observed not only in the uranium intermetallic ferromagnets with the itinerant 5f electrons but also in the low carrier concentration systems UTeS and USeS with the localized 5f electrons. The large negative magnetoresistance in UTeS and USeS, and the superconductivity in UGe_2 and URhGe share the similarity of their closeness to the ferromagnetism characterized by the novel critical exponents.
To measure the mass loss from dusty oxygen-rich (O-rich) evolved stars in the Large Magellanic Cloud (LMC), we have constructed a grid of models of spherically-symmetric dust shells around stars with constant mass-loss rates using 2Dust. These models will constitute the O-rich model part of the "Grid of Red supergiant and Asymptotic giant branch star ModelS" (GRAMS). This model grid explores 4 parameters - stellar effective temperature from 2100 K - 4700 K; luminosity from 10^3-10^6 L_Sun; dust shell inner radii of 3, 7, 11, and 15 R_Star; and 10.0 micron optical depth from 10^-4 to 26. From an initial grid of ~1200 2Dust models, we create a larger grid of ~69,000 models by scaling to cover the luminosity range required by the data. These models are offered to the public on a website. The matching in color-magnitude diagrams and color-color diagrams to observed O-rich asymptotic giant branch (AGB) and red supergiant (RSG) candidate stars from the SAGE and SAGE-Spec LMC samples and a small sample of OH/IR stars is generally very good. The extreme AGB star candidates from SAGE are more consistent with carbon-rich (C-rich) than O-rich dust composition. Our model grid suggests lower limits to the mid-infrared colors of the dustiest AGB stars for which the chemistry could be O-rich. Finally, the fitting of GRAMS models to SEDs of sources fit by other studies provides additional verification of our grid and anticipates future, more expansive efforts.
We present new and accurate near-infrared (NIR) J, K-band time series data for the Galactic globular cluster (GC) M5 = NGC5904. Data were collected with SOFI at the NTT (71 J + 120 K images) and with NICS at the TNG (25 J + 22 K images) and cover two orthogonal strips across the center of the cluster of \approx 5 \times 10 arcmin^{2} each. These data allowed us to derive accurate mean K-band magnitudes for 52 fundamental (RR_{ab}) and 24 first overtone (RR_{c}) RR Lyrae stars. Using this sample of RR Lyrae stars, we find that the slope of the K-band Period Luminosity (PLK) relation (-2.33 \pm 0.08) agrees quite well with similar estimates available in the literature. We also find, using both theoretical and empirical calibrations of the PLK relation, a true distance to M5 of (14.44 \pm 0.02) mag. This distance modulus agrees very well (1\sigma) with distances based on main sequence fitting method and on kinematic method (14.44 \pm 0.41 mag, \citealt{rees_1996}), while is systematically smaller than the distance based on the white dwarf cooling sequence (14.67 \pm 0.18 mag, \citealt{layden2005}), even if with a difference slightly larger than 1\sigma. The true distance modulus to M5 based on the PLJ relation (14.50 \pm 0.08 mag) is in quite good agreement with the distance based on the PLK relation further supporting the use of NIR PL relations for RR Lyrae stars to improve the precision of the GC distance scale.
A large set of high precision full-Stokes spectropolarimetric observations of the He-D3 line in spicules has been recorded with the ZIMPOL polarimeter at the Gregory-Coude Telescope in Locarno. The observational technique allow us to obtain measurements free from seeing induced spurious effects. The instrumental polarization is well under control and taken into account in the data analysis. The observed Stokes profiles are interpreted according to the quantum theory of the Hanle and Zeeman effects with the aim of obtaining information on the magnetic field vector. To this end, we make use of a suitable Stokes inversion technique. The results are presented giving emphasis on a few particularly interesting measurements which show clearly the operation of the Hanle and Zeeman effects in solar chromospheric spicules.
We use a new panoramic imaging survey, conducted with the Dark Energy Camera, to map the stellar fringes of the Large and Small Magellanic Clouds to extremely low surface brightness V $\gtrsim$ 32 mag arcsec$^{-2}$. Our results starkly illustrate the closely interacting nature of the LMC-SMC pair. We show that the outer LMC disk is strongly distorted, exhibiting an irregular shape, evidence for warping, and significant truncation on the side facing the SMC. Large diffuse stellar substructures are present both to the north and south of the LMC, and in the inter-Cloud region. At least one of these features appears co-spatial with the bridge of RR Lyrae stars that connects the Clouds. The SMC is highly disturbed -- we confirm the presence of tidal tails, as well as a large line-of-sight depth on the side closest to the LMC. Young, intermediate-age, and ancient stellar populations in the SMC exhibit strikingly different spatial distributions. In particular, those with ages $\sim$ 1.5-4 Gyr exhibit a spheroidal distribution with a centroid offset from that of the oldest stars by several degrees towards the LMC. We speculate that the gravitational influence of the LMC may already have been perturbing the gaseous component of the SMC several Gyr ago. With careful modeling, the variety of substructures and tidal distortions evident in the Magellanic periphery should tightly constrain the interaction history of the Clouds.
We consider constrained variants of graph homomorphisms such as embeddings, monomorphisms, full homomorphisms, surjective homomorpshims, and locally constrained homomorphisms. We also introduce a new variation on this theme which derives from relations between graphs and is related to multihomomorphisms. This gives a generalization of surjective homomorphisms and naturally leads to notions of R-retractions, R-cores, and R-cocores of graphs. Both R-cores and R-cocores of graphs are unique up to isomorphism and can be computed in polynomial time.   The theory of the graph homomorphism order is well developed, and from it we consider analogous notions defined for orders induced by constrained homomorphisms. We identify corresponding cores, prove or disprove universality, characterize gaps and dualities. We give a new and significantly easier proof of the universality of the homomorphism order by showing that even the class of oriented cycles is universal. We provide a systematic approach to simplify the proofs of several earlier results in this area. We explore in greater detail locally injective homomorphisms on connected graphs, characterize gaps and show universality. We also prove that for every $d\geq 3$ the homomorphism order on the class of line graphs of graphs with maximum degree $d$ is universal.
We consider non-compact branes in topological string theories on a class of Calabi-Yau spaces including the resolved conifold and its mirror. We compute the amplitudes of the insertion of non-compact Lagrangian branes in the A-model on the resolved conifold in the context of the topological vertex as well as the melting crystal picture. They all agree with each other and also agree with the results from Chern-Simons theory, supporting the large N duality. We find that they obey the Schr\"odinger equation confirming the wavefunction behavior of the amplitudes. We also compute the amplitudes of the non-compact B-branes in the DV matrix model which arises as a B-model open string field theory on the mirror manifold of the deformed conifold. We take the large N duality to consider the B-model on the mirror of the resolved conifold and confirm the wave function behavior of this amplitude. We find appropriate descriptions of non-compact branes in each model, which give complete agreements among those amplitudes and clarify the salient features including the role of symmetries toward these agreements.
We investigate the existence and first percolation properties of general stopped germ-grain models. They are defined via a random set of germs generated by a homogeneous planar Poisson point process in $\mathbf{R}^{2}$. From each germ, a grain, composed by a random number of branches, grows. This grain stops to grow whenever one of its branches hits another grain. The classical and historical example is the line segment model for which the grains are segments growing in a random direction in $ [0,2\pi)$ with random velocity. In the bilateral line segment model the segments grow in both directions. Other examples are considered here such as the Brownian model where the branches are simply given by independent Brownian motions in $\mathbf{R}^{2}$. The existence of such dynamics for an infinite number of germs is not obvious and our first result ensures it in a very general setting. In particular the existence of the line segment model is proved as soon as the random velocity admits a moment of order 4 which extends the result by Daley et al (Theorem 4.3 in \cite{daley2014two}) for bounded velocity. Our result covers also the Brownian dynamic model. In a second part of the paper, we show that the line segment model with random velocity admitting a super exponential moment does not percolate. This improves a recent result (Theorem 3.2 \cite{coupier2016absence}) in the case of bounded velocity.
We consider cosmological dynamics in the theory of gravity with the scalar field possessing a nonminimal kinetic coupling to gravity, $\kappa G_{\mu\nu}\phi^{\mu}\phi^{\nu}$, and the power-law potential $V(\phi)=V_0\phi^N$. Using the dynamical system method, we analyze all possible asymptotical regimes of the model under investigation and show that for sloping potentials with $0<N<2$ there exists a quasi-de Sitter asymptotic $H={1}/{\sqrt{9\kappa}}$ corresponding to an early inflationary Universe. In contrast to the standard inflationary scenario, the kinetic coupling inflation does not depend on a scalar field potential and is only determined by the coupling parameter $\kappa$. We obtain that there exist two different late-time asymptotical regimes. The first one leads to the usual power-like cosmological evolution with $H=1/3t$, while the second one represents the late-time inflationary Universe with $H=1/\sqrt{3\kappa}$. This secondary inflationary phase depends only on $\kappa$ and is a specific feature of the model with nonminimal kinetic coupling. Additionally, an asymptotical analysis shows that for the quadric potential with N=2 the asymptotical regimes remain qualitatively the same, while the kinetic coupling inflation is impossible for steep potentials with N>2. Using a numerical analysis, we also construct exact cosmological solutions and find initial conditions leading to the initial kinetic coupling inflation followed either by a "graceful" oscillatory exit or by the secondary inflation.
A simple model of a vibrated granular monolayer is studied. It consists of inelastic hard spheres confined between two parallel hard plates separated a distance smaller than twice the diameter of the particles. Both walls are elastic and one of them is vibrating in a sawtooth way. For low densities, a kinetic equation is proposed from which closed evolution equations for the horizontal and vertical temperatures are derived assuming spatial homogeneity and that the system is very thin. An excellent agreement between the theoretical predictions and Molecular Dynamics simulation results is obtained both, for the stationary values and for the dynamics of the temperatures.
We use reverse non-equilibrium molecular dynamics (RNEMD) simulations to determine the thermal conductivity in $\alpha$-RDX in the <100>, <010>, and <001> crystallographic directions. Simulations are carried out with the Smith-Bharadwaj non-reactive empirical interatomic potential [Smith & Bharadwaj, J. Phys. Chem. B 103, 3570(1999)], which represents the thermo-elastic properties of RDX with good accuracy. As an illustration, we report the temperature and pressure dependence of lattice constants of $\alpha$-RDX, which compare well with experimental and ab initio results, as do linear and volume thermal expansion coefficients, which we also calculate. We find that the thermal conductivity depends linearly on the inverse temperature in the 200-400K regime due to the decrease in the phonon mean free path. The thermal conductivity also exhibits anisotropy, with a maximum difference at 300K of 24% between the <001> and <010> directions, an effect that remains when temperature increases. Thermal conductivity in the <100> direction is mostly between the two other directions, although crossovers are predicted with <001> at high temperature, and <010> at low temperature under pressure. We observe that the thermal conductivity varies linearly with pressure up to 4 GPa. The data are fitted to analytical functions for interpolation/extrapolation and use in continuum simulations. MD results are validated against experiments using impulsive stimulated thermal scattering (ISTS) on RDX single crystals at 293K and ambient pressure, showing good qualitative and quantitative agreement: same ordering between the three principal orientations, and an average error of 10% between the experiments and the model. These results provide confidence that the extracted analytical functions using the RNEMD methodology and the Smith-Bharadwaj potential can be applied to model the thermal conductivity of $\alpha$-RDX.
Dense granular clusters often behave like macro-particles. We address this interesting phenomenon in a model system of inelastically colliding hard disks inside a circular box, driven by a thermal wall at zero gravity. Molecular dynamics simulations show a close-packed cluster of an almost circular shape, weakly fluctuating in space and isolated from the driving wall by a low-density gas. The density profile of the system agrees very well with the azimuthally symmetric solution of granular hydrostatic equations employing constitutive relations by Grossman et al., whereas the widely used Enskog-type constitutive relations show poor accuracy. We find that fluctuations of the center of mass of the system are Gaussian. This suggests an effective Langevin description in terms of a macro-particle, confined by a harmonic potential and driven by a delta-correlated noise. Surprisingly, the fluctuations persist when increasing the number of particles in the system.
This white paper briefly summarizes the importance of the study of relativistic cosmic rays, both as a constituent of our Universe, and through their impact on stellar and galactic evolution. The focus is on what can be learned over the coming decade through ground-based gamma-ray observations over the 20 GeV to 300 TeV range. The majority of the material is drawn directly from "Science with the Cherenkov Telescope Array", which describes the overall science case for CTA. We request that authors wishing to cite results contained in this white paper cite the original work.
One of the key questions concerning frustrated lattices that has lately emerged is the role of disorder in inducing spin-liquid-like properties. In this context, the quantum kagome antiferromagnets YCu$_3$(OH)$_6$Cl$_3$, which has been recently reported as the first geometrically perfect realization of the kagome lattice with negligible magnetic/non-magnetic intersite mixing and a possible quantum-spin-liquid ground state, is of particular interest. However, contrary to previous conjectures, here we show clear evidence of bulk magnetic ordering in this compound below $T_N=15$\,K by combining bulk magnetization and heat capacity measurements, and local-probe muon spin relaxation measurements. The magnetic ordering in this material is rather unconventional in several respects. Firstly, a crossover regime where the ordered state coexists with the paramagnetic state extends down to $T_N/3$ and, secondly, the fluctuation crossover is shifted far below $T_N$. Moreover, a reduced magnetic-entropy release at $T_N$ and persistent spin dynamics that is observed at temperatures as low as $T/T_N=1/300$ could be a sign of emergent excitations of correlated spin-loops or, alternatively, a sign of fragmentation of each magnetic moment into an ordered and a fluctuating part.
We find and prove a class of congruences modulo 4 for Andrews' partition with certain ternary quadratic form. We also discuss distribution of $\overline{\mathcal{EO}}(n)$ and further prove that $\overline{\mathcal{EO}}(n)\equiv0\pmod4$ for almost all $n$. This study was inspired by similar congruences modulo 4 in the work by the second author and Garvan.
Selected recent contributions involving fluctuating velocity fields to the rapidly developing domain of stochastic field theory are reviewed. Functional representations for solutions of stochastic differential equations and master equations are worked out in detail with an em- phasis on multiplicative noise and the inherent ambiguity of the functional method. Application to stochastic models of isotropic turbulence of multi-parameter expansions in regulators of dimensional and analytic renormalization is surveyed. Effects of the choice of the renormalization scheme are investigated. Special attention is paid to the role and properties of the minimal subtraction scheme. Analysis of the consequences of symmetry breaking of isotropic turbulence with the use of the renormalization-group method is demonstrated by the effects due to helicity, strong and weak anisotropy. A careful description is given of the influence of turbulent advection on paradigmatic reaction-diffusion problems.
The NRAO VLA Sky Survey (NVSS) is the only dataset that allows an accurate determination of the auto-correlation function (ACF) on angular scales of several degrees for Active Galactic Nuclei (AGNs) at typical redshifts $z \simeq 1$. Surprisingly, the ACF is found to be positive on such large scales while, in the framework of the standard hierarchical clustering scenario with Gaussian primordial perturbations it should be negative for a redshift-independent effective halo mass of order of that found for optically-selected quasars. We show that a small primordial non-Gaussianity can add sufficient power on very large scales to account for the observed NVSS ACF. The best-fit value of the parameter $f_{\rm NL}$, quantifying the amplitude of primordial non-Gaussianity of local type is $f_{\rm NL}=62 \pm 27$ ($1\,\sigma$ error bar) and $25<f_{\rm NL}<117$ ($2\,\sigma$ confidence level), corresponding to a detection of non-Gaussianity significant at the $\sim 3\,\sigma$ confidence level. The minimal halo mass of NVSS sources is found to be $M_{\rm min}=10^{12.47\pm0.26}h^{-1}M_{\odot}$ ($1\,\sigma$) strikingly close to that found for optically selected quasars. We discuss caveats and possible physical and systematic effects that can impact on the results.
We studied two objects identified as a Cataclysmic Variables (CVs) with periods exceeding the natural boundary for Roche lobe filling ZAMS secondary stars. We present observational results for V1082 Sgr with 20.82 h orbital period, an object that shows low luminosity state, when its flux is totally dominated by a chromospherically active K- star with no signs of ongoing accretion. Frequent accretion shut-offs, together with characteristics of emission lines in a high state, indicate that this binary system is probably detached and the accretion of matter on the magnetic white dwarf takes place through stellar wind from the active donor star via coupled magnetic fields. Its observational characteristics are surprisingly similar to V479 And, a 14.5 h binary system. They both have early K-type stars as a donor star. We argue, that similar to the shorter period pre-polars containing M-dwarfs, these are detached binaries with strong magnetic components. Their magnetic fields are coupled, allowing enhanced stellar wind from the K star to be captured and channeled through the bottleneck connecting the two stars onto the white dwarf's magnetic pole, mimicking a magnetic CV. Hence, they become interactive binaries before they reach contact. This will help to explain an unexpected lack of systems possessing white dwarfs with strong magnetic fields among detached white + red dwarf systems.
We report fourteen and twenty-eight protocluster candidates at z=5.7 and 6.6 over 14 and 19 deg^2 areas, respectively, selected from 2,230 (259) Lya emitters (LAEs) photometrically (spectroscopically) identified with Subaru/Hyper Suprime-Cam (HSC) deep images (Keck, Subaru, and Magellan spectra and the literature data). Six out of the 42 protocluster candidates include 1-12 spectroscopically confirmed LAEs at redshifts up to z=6.574. By the comparisons with the cosmological Lya radiative transfer (RT) model reproducing LAEs with the reionization effects, we find that more than a half of these protocluster candidates are progenitors of the present-day clusters with a mass of > 10^14 M_sun. We then investigate the correlation between LAE overdensity delta and Lya rest-frame equivalent width EW_Lya^rest, because the cosmological Lya RT model suggests that a slope of EW_Lya^rest-delta relation is steepened towards the epoch of cosmic reionization (EoR), due to the existence of the ionized bubbles around galaxy overdensities easing the escape of Lya emission from the partly neutral intergalactic medium (IGM). The available HSC data suggest that the slope of the EW_Lya^rest-delta correlation does not evolve from the post-reionization epoch z=5.7 to the EoR z=6.6 beyond the moderately large statistical errors. There is a possibility that we would detect the evolution of the EW_Lya^rest - delta relation from z=5.7 to 7.3 by the upcoming HSC observations providing large samples of LAEs at z=6.6-7.3.
We present the formalism for consistently transforming transition operators within the in-medium similarity renormalization group framework. We implement the operator transformation in both the equations-of-motion and valence-space variants, and present first results for electromagnetic transitions and moments in medium-mass nuclei using consistently-evolved operators, including the induced two-body parts. These results are compared to experimental values, and--where possible--the results of no-core shell model calculations using the same input chiral interaction. We find good agreement between the equations-of-motion and valence space approaches. Magnetic dipole observables are generally in reasonable agreement with experiment, while the more collective electric quadrupole and octupole observables are significantly underpredicted, often by over an order of magnitude, indicating missing physics at the present level of truncation.