ShantanuT01/DACTYL-Pretraining huggingface dataset:
We report a search for fluctuations of the sky brightness toward the north ecliptic pole (NEP) with the Japanese infrared astronomical satellite AKARI,at 2.4, 3.2, and 4.1 \mum. We obtained circular maps with 100 diameter field of view which clearly show a spatial structure on scale of a few hundred arcsec. A power spectrum analysis shows that there is a significant excess fluctuation at angular scales larger than 10000 that can't be explained by zodiacal light, diffuse Galactic light, shot noise of faint galaxies or clustering of low redshift galaxies. These results are consistent with observations at 3.6 and 4.5 \mum by NASA's Spitzer Space Telescope. The fluctuating component observed at large angular scales has a blue stellar spectrum which is similar to that of the spectrum of the excess isotropic emission observed with IRTS. A significant spatial correlation between wavelength bands was found, and the slopes of the linear correlations is consistent with the spectrum of the excess fluctuation. These findings indicate that the detected fluctuation could be attributed to the first stars of the universe, i.e. pop. III stars. The observed fluctuation provides an important constraints on the era of the first stars.
A mechanism is proposed to describe the occurrence of distance-dependent dissipation peaks in the dynamics of an atomic force microscope tip oscillating over a surface characterized by a charge density wave state. The dissipation has its origin in the hysteretic behavior of the tip oscillations occurring at positions compatible with a localized phase slip of the charge density wave. This model is supported through static and dynamic numerical simulations of the tip surface interaction and is in good qualitative agreement with recently performed experiments on a NbSe$_2$ sample.
We present the full sample of 118 galaxy-scale strong-lens candidates in the Sloan Lens ACS (SLACS) Survey for the Masses (S4TM) Survey, which are spectroscopically selected from the final data release of the Sloan Digital Sky Survey. Follow-up Hubble Space Telescope (HST) imaging observations confirm that 40 candidates are definite strong lenses with multiple lensed images. The foreground lens galaxies are found to be early-type galaxies (ETGs) at redshifts 0.06 to 0.44, and background sources are emission-line galaxies at redshifts 0.22 to 1.29. As an extension of the SLACS Survey, the S4TM Survey is the first attempt to preferentially search for strong-lens systems with relatively lower lens masses than those in the pre-existing strong-lens samples. By fitting HST data with a singular isothermal ellipsoid model, we find total projected mass within the Einstein radius of the S4TM strong-lens sample ranges from $3 \times10^{10} M_{\odot}$ to $2 \times10^{11} M_{\odot}$. In [Shu15], we have derived the total stellar mass of the S4TM lenses to be $5 \times10^{10} M_{\odot}$ to $1 \times10^{12} M_{\odot}$. Both total enclosed mass and stellar mass of the S4TM lenses are on average almost a factor of 2 smaller than those of the SLACS lenses, which also represent typical mass scales of the current strong-lens samples. The extended mass coverage provided by the S4TM sample can enable a direct test, with the aid of strong lensing, for transitions in scaling relations, kinematic properties, mass structure, and dark-matter content trends of ETGs at intermediate-mass scales as noted in previous studies.
The quadrupole formula in four-dimensional Einstein gravity is a useful tool to describe gravitational wave radiation. We derive the quadrupole formula for the Kaluza-Klein (KK) modes in the Randall-Sundrum braneworld model. The quadrupole formula provides transparent representation of the exterior weak gravitational field induced by localized sources. We find that a general isolated dynamical source gives rise to the 1/r^2 correction to the leading 1/r gravitational field. We apply the formula to an evaluation of the effective energy carried by the KK modes from the viewpoint of an observer on the brane. Contrary to the ordinary gravitational waves (zero mode), the flux of the induced KK modes by the non-spherical part of the quadrupole moment vanishes at infinity and only the spherical part contributes to the flux. Since the effect of the KK modes appears in the linear order of the metric perturbations, the effective energy flux observed on the brane is not always positive, but can become negative depending on the motion of the localized sources.
We study the dependence on various parameters of the exceptional set in Vojta's conjecture. In particular, by making use of certain elliptic surfaces, we answer in the negative the often-raised question of whether Vojta's conjecture holds when extended to all algebraic points (that is, if the conjecture holds without fixing a bound on the degree of the algebraic points).
Understanding collective phenomena in quantum materials from first principles is a promising route toward engineering materials properties on demand and designing new functionalities. This work examines the quantum paraelectric state, an elusive state of matter characterized by the smooth saturation of the ferroelectric instability at low temperature due to quantum fluctuations associated with anharmonic phonon effects. The temperature-dependent evolution of the soft ferroelectric phonon mode in the quantum paraelectric KTaO$_3$ in the range 0-300 K is modelled by combining density functional theory (DFT) calculations with the stochastic self-consistent harmonic approximation assisted by an on-the-fly machine-learned force field. The calculated data show that including anharmonic terms is essential to stabilize the spurious imaginary ferroelectric phonon predicted by DFT, in agreement with experiments. Augmenting the DFT workflow with machine-learned force fields allows for efficient stochastic sampling of the configurational space using large supercells in a broad and dense temperature range, inaccessible by conventional ab initio protocols. This work proposes a robust computational workflow capable of accounting for collective behaviors involving different degrees of freedom and occurring at large time/length scales, paving the way for precise modeling and control of quantum effects in materials.
In this paper, we study the quasinormal modes of the massless Dirac field for charged black holes in Rastall gravity. The spherically symmetric black hole solutions in question are characterized by the presence of a power-Maxwell field, surrounded by the quintessence fluid. The calculations are carried out by employing the WKB approximations up to the thirteenth order, as well as the matrix method. The temporal evolution of the quasinormal modes is investigated by using the finite difference method. Through numerical simulations, the properties of the quasinormal frequencies are analyzed, including those for the extremal black holes. Among others, we explore the case of a second type of extremal black holes regarding the Nariai solution, where the cosmical and event horizon coincide. The results obtained by the WKB approaches are found to be mostly consistent with those by the matrix method. It is demonstrated that the black hole solutions for Rastall gravity in asymptotically flat spacetimes are equivalent to those in Einstein gravity, featured by different asymptotical spacetime properties. As one of its possible consequences, we also investigate the behavior of the late-time tails of quasinormal models in the present model. It is found that the asymptotical behavior of the late-time tails of quasinormal modes in Rastall theory is governed by the asymptotical properties of the spacetimes of their counterparts in Einstein gravity.
The integral relations formalism introduced in \cite{bar09,rom11}, and designed to describe 1+$N$ reactions, is extended here to collision energies above the threshold for the target breakup. These two relations are completely general, and in this work they are used together with the adiabatic expansion method for the description of 1+2 reactions. The neutron-deuteron breakup, for which benchmark calculations are available, is taken as a test of the method. The s-wave collision between the $^4$He atom and $^4$He$_2$ dimer above the breakup threshold and the possibility of using soft-core two-body potentials plus a short-range three-body force will be investigated. Comparisons to previous calculations for the three-body recombination and collision dissociation rates will be shown.
The emission and absorption attributes of the UV-blue nuclear spectra of the Narrow-Line Seyfert 1 (NLS1) galaxies are analyzed based on high quality archival HST observations. Measurements from composite spectra as well as from individual sources reveal differences from the more general AGN samples: NLS1s have steeper (redder) UV-blue continua. Objects with UV line absorption show redder spectra, suggesting that internal dust is important in modifying the continuum shapes. A strong relationship is found between the slopes of the power-laws that best fit the UV-blue continua and the luminosities: the more luminous sources have bluer SEDs. This trend is possibly attributed to a luminosity-dependent inner geometry of the obscuring (dusty) material.
In this paper we analyse the selection problem for weak solutions of the transport equation with rough vector field. We answer in the negative the question whether solutions of the equation with a regularized vector field converge to a unique limit, which would be the selected solution of the limit problem. To this aim, we give a new example of a vector field which admits infinitely many flows. Then we construct a smooth approximating sequence of the vector field for which the corresponding solutions have subsequences converging to different solutions of the limit equation.
Line segmentation from handwritten text images is one of the challenging task due to diversity and unknown variations as undefined spaces, styles, orientations, stroke heights, overlapping, and alignments. Though abundant researches, there is a need of improvement to achieve robustness and higher segmentation rates. In the present work, an adaptive approach is used for the line segmentation from handwritten text images merging the alignment of connected component coordinates and text height. The mathematical justification is provided for measuring the text height respective to the image size. The novelty of the work lies in the text height calculation dynamically. The experiments are tested on the dataset provided by the Chinese company for the project. The proposed scheme is tested on two different type of datasets; document pages having base lines and plain pages. Dataset is highly complex and consists of abundant and uncommon variations in handwriting patterns. The performance of the proposed method is tested on our datasets as well as benchmark datasets, namely IAM and ICDAR09 to achieve 98.01% detection rate on average. The performance is examined on the above said datasets to observe 91.99% and 96% detection rates, respectively.
We add to Galilean symmetries the transformations describing constant accelerations. The corresponding extended Galilean algebra allows, in any dimension $D=d+1$, the introduction of one central charge $c$ while in $D=2+1$ we can have three such charges: c, \theta and \theta'.   We present nonrelativistic classical mechanics models, with higher order time derivatives and show that they give dynamical realizations of our algebras. The presence of central charge $c$ requires the acceleration square Lagrangian term. We show that the general Lagrangian with three central charges can be reinterpreted as describing an exotic planar particle coupled to a dynamical electric and a constant magnetic field.
To establish a time reference frame between two users in quantum key distribution, a synchronization calibration process is usually applied for the case of using gated mode single-photon detectors (SPDs). Traditionally, the synchronization calibration is independently implemented by the line length measurement for each SPD. However, this will leave a loophole which has been experimentally demonstrated by a special attack. Here, we propose an alternative synchronization scheme by fixing the relative delay of the signal time window among all SPDs and jointly performing the line length measurement with multiple SPDs under combining low-precision with high-precision synchronization. The new scheme is not only immune to the vulnerability but also improves the synchronization time from usually a few seconds to tens of milliseconds.
We show that chiral symmetry can be broken spontaneously in one-component systems with isotropic interactions, i.e. many-particle systems having maximal a priori symmetry. This is achieved by designing isotropic potentials that lead to self-assembly of chiral surfaces. We demonstrate the principle on a simple chiral lattice and on a more complex lattice with chiral super-cells. In addition we show that the complex lattice has interesting melting behavior with multiple morphologically distinct phases that we argue can be qualitatively predicted from the design of the interaction.
We consider heat transport through systems with broken time-reversal symmetry. We apply strong magnetic fields to weakly charged particle systems, where the dynamics are dominated by the Lorentz force and spring forces. The standard momentum conservation is not satisfied and the sound wave disappears depending on the charge structure. We introduce an exactly solvable model and demonstrate the appearance of a new universality class. The absence of sound waves affects the relation between equilibrium correlation and the diverging thermal conductivity in the open system.
The phenomenon of magnetization plateaus in antiferromagnets under magnetic field has always been an important topic in magnetism. We propose to probe the elusive physics of plateaus in 2-d by considering hole-doped antiferromagnet and studying the signatures of magnetization plateaus in terms of the properties of holes, coupled to an effective gauge field generated by the spin sector. The latter mediates interaction between the holes, found to be algebraically decaying long-ranged with both Coulombic and dipolar forms outside plateau and short-ranged (local) inside plateau. The resulting hole spectral weight is significantly broadened off-plateau, while it remains sharply-peaked on-plateau. We also extend the result obtained for 1-d system where finite hole doping gives rise to a shift in the magnetization value of the plateaus.
Polarization-dependent reflectivity measurements were carried out over a broad frequency range on single-crystalline ZrGeSe and ZrGeS compounds, which are closely related to the prototype nodal-line semimetal ZrSiS. These measurements revealed the strongly anisotropic character of both ZrGeSe and ZrGeS, with a reduced plasma frequency for the out-of-plane direction {\bf E}$\| c$ as compared to the in-plane direction {\bf E}$\| ab$. For {\bf E}$\| ab$ the optical conductivity spectrum consists of two Drude terms followed by a shoulder or plateau-like behavior and a distinct U shape at higher energies, while for {\bf E}$\| c$ one Drude term is followed by a peak-like behavior and the U shape of the profile is less developed. Under external pressure, two prominent excitations appear in the out-of-plane optical conductivity spectrum of ZrGeSe, whose frequency position and oscillator strength show a weak anomaly at $\sim$3~GPa. Overall, the pressure-induced changes in the profile of the {\bf E}$\| c$ conductivity spectrum are much enhanced above $\sim$3~GPa. We compare our results to those recently reported for ZrSiS in a quantitative manner.
ASASSN-14ko is a recently discovered periodically flaring transient at the center of the AGN ESO 253-G003 with a slowly decreasing period. Here we show that the flares originate from the northern, brighter nucleus in this dual-AGN, post-merger system. The light curves for the two flares that occurred in May 2020 and September 2020 are nearly identical over all wavelengths. For both events, Swift observations showed that the UV and optical wavelengths brightened in unison. The effective temperature of the UV/optical emission rises and falls with the increase and subsequent decline in the luminosity. The X-ray flux, in contrast, first rapidly drops over $\sim$2.6 days, rises for $\sim$5.8 days, drops again over $\sim$4.3 days and then recovers. The X-ray spectral evolution of the two flares differ, however. During the May 2020 peak the spectrum softened with increases in the X-ray luminosity, while we observed the reverse for the September 2020 peak.
We consider an inertial active Ornstein-Uhlenbeck particle in an athermal bath. The particle is charged, constrained to move in a two-dimensional harmonic trap, and a magnetic field is applied perpendicular to the plane of motion. The steady state correlations and the mean square displacement are studied when the particle is confined as well as when it is set free from the trap. With the help of both numerical simulation and analytical calculations, we observe that inertia plays a crucial role in the dynamics in the presence of a magnetic field. In a highly viscous medium where the inertial effects are negligible, the magnetic field has no influence on the correlated behaviour of position as well as velocity. In the time asymptotic limit, the overall displacement of the confined harmonic particle gets enhanced by the presence of magnetic field and saturates for a stronger magnetic field. On the other hand, when the particle is set free, the overall displacement gets suppressed and approaches zero when strength of the field is very high. Interestingly, it is seen that in the time asymptotic limit, the confined harmonic particle behaves like a passive particle and becomes independent of the activity, especially in the presence of a very strong magnetic field. Similarly, for a free particle the mean square displacement in the long time limit becomes independent of activity even for a longer persistence of noise correlation in the dynamics.
The hadronic light-by-light scattering contribution to muon $g-2$ is examined based on the low energy effective theories of QCD, the Nambu-Jona-Lasinio model and hidden local symmetry approach, supplemented by a general information concerning the asymptotic behavior of QCD.   Our result is $- 52 \times 10^{-11}$ with an uncertainty of $\pm 18 \times 10^{-11}$, which includes our best estimate of model dependence. This is within the expected measurement uncertainty of $40\times 10^{-11}$ in the forthcoming experiment at Brookhaven National Laboratory. Our result removes one of the main theoretical obstacles in verifying the existence of the weak contribution to the muon $g-2$.
In this article we review essential natures of superconductivity in strongly correlated electron systems (SCES) from a universal point of view. After summarizing experimental results on typical materials such as high-$T_{\rm c}$ cuprates, BEDT-TTF organic superconductors, and ruthenate Sr$_2$RuO$_4$, we review theoretical results for the analyses of superconducting properties of these materials based on the Fermi-liquid framework in the single- and multi-band Hubbard model. It is emphasized that the Coulomb interaction induces various types of anisotropic superconductivity, $d$- or p-wave, through the momentum dependence of quasi-particle interaction. While some inter-orbital interactions exist in the multi-orbital system, anisotropic superconductivity is induced by essentially the same mechanism, namely the momentum dependence of quasi-particle interaction. This is the understanding of the mechanism of superconductivity in SCES. Another important purpose of this article is to review anomalous electronic properties of SCES near the Mott transition. Especially, we focus on pseudogap phenomena observed in under-doped cuprates and organic superconductors. According to the recent theory, superconducting fluctuations, inherent in the quasi-two-dimensional and strong-coupling superconductors, are the origin of the pseudogap formation. Based on the microscopic theory of the superconducting fluctuations, we discuss the magnetic and transport properties as well as the single-particle spectra in the pseudogap state. As for heavy-fermion superconductors, experimental results are reviewed and several theoretical analyses on the mechanism are provided based on the same viewpoint as explained above.
We present the results of a search for cool white dwarfs in the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). The UKIDSS LAS photometry was paired with the Sloan Digital Sky Survey (SDSS) to identify cool hydrogen-rich white dwarf candidates by their neutral optical colors and blue near-infrared colors, as well as faint Reduced Proper Motion magnitudes. Optical spectroscopy was obtained at Gemini Observatory, and showed the majority of the candidates to be newly identified cool degenerates, with a small number of G- to K-type (sub)dwarf contaminants. Our initial search of 280 deg2 of sky resulted in seven new white dwarfs with effective temperature T_eff ~ 6000 K. The current followup of 1400 deg2 of sky has produced thirteen new white dwarfs. Model fits to the photometry show that seven of the newly identified white dwarfs have 4120 K <= T_eff <= 4480 K, and cooling ages between 7.3 Gyr and 8.7 Gyr; they have 40 km/s <= v_tan <= 85 km/s and are likely to be thick disk 10-11 Gyr-old objects. The other half of the sample has 4610 K <= T_eff <= 5260 K, cooling ages between 4.3 Gyr and 6.9 Gyr, and 60 km/s <= v_tan <= 100 km/s. These are either thin disk remnants with unusually high velocities, or lower-mass remnants of thick disk or halo late-F or G stars.
Green and Tao proved that the primes contains arbitrarily long arithmetic progressions. We show that, essentially the same proof leads to the following result: The primes in an short interval contains many arithmetic progressions of any given length.
We present measurements of radial velocities for the narrow-line region gas (NLR) in the Seyfert 2 galaxy Mrk 3 out to ~1 kpc from the nucleus. The observations consist of two datasets, both using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope: 1) An [O III] slitless spectrum with the G430M grating of the inner 3" around the nucleus, and 2) a long-slit observation centered on the nucleus (PA = 71 deg) using the G430L grating and the 52" x 0".1 aperture. Our results produce radial velocity maps of the emission-line gas. These maps indicate general trends in the gas motion, which include: blueshifts and redshifts on either side of the nucleus, steep velocity rises from systemic up to ~ +/-700 km/s taking place in the inner 0".3 (0.8 kpc) both east and west of the nucleus, gradual velocity descents back to near-systemic values from 0".3-1".0, slightly uneven velocity amplitudes on each side of the nucleus, and narrow velocity ranges over the entire observed region. When fitted to kinematic modeling programs for the NLR gas, the data clearly favor a model where the gas exists in a partially filled bicone, is accelerated radially away from the nucleus, and is followed by a constant deceleration. This geometry and general kinematic model is in agreement with previous work done on the NLR gas of NGC 1068 and NGC 4151. On scales of hundreds of parsecs, we conclude that radial outflow may be a common feature of Seyfert galaxies.
We introduce the 2PPI (2-point-particle-irreducible) expansion, which sums bubble graphs to all orders. We prove the renormalizibility of this summation. We use it on the Gross-Neveu model to calculate the mass gap and vacuum energy. After an optimization of the expansion, the final results are qualitatively good.