ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present the SCUBA-2 850 ${\mu}m$ component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at 850 ${\mu}m$. We provide details of our SCUBA-2 data reduction pipeline, optimised for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE and SCUBA-2 850 ${\mu}m$ maps, statistically accounting for the contamination by CO(J=3-2) in the 850 ${\mu}m$ band. Of our initial sample of 193 galaxies, 191 are detected at 250 ${\mu}m$ with a $\geq$ 5${\sigma}$ significance. In the SCUBA-2 850 ${\mu}m$ band we detect 126 galaxies with $\geq$ 3${\sigma}$ significance. The distribution of the JINGLE galaxies in far-infrared/sub-millimetre colour-colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index $(\beta)$. Instead, our new 850 ${\mu}m$ data suggest either that a large fraction of our objects require $\beta < 1.5$, or that a model allowing for an excess of sub-mm emission (e.g., a broken dust emissivity law, or a very cold dust component 10 K) is required. We provide relations to convert far-infrared colours to dust temperature and $\beta$ for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample.
The two-point gauge-invariant correlation function of gluonic field strengths, which is the main input in the stochastic vacuum model, is derived by using its relation to the Green functions of one- and two-gluon gluelumps. These Green functions are found by evaluating the path integrals of one and two gluons confined in the field of an infinitely heavy adjoint source. This allows one to obtain also the terms in the exponential asymptotics of the two-point correlation function, which are produced by fluctuations of the gluons around their mean separation from the source. The pre-exponents are derived as well, demonstrating some novel dependences on the distance.
Context: We present the results of Suzaku observations of a massive galaxy cluster A2744, which is an active merger at $z=0.308$. Aims: By using long X-ray observations of A2744, we aim to understand the growth of the cluster and the gas heating process through mass accretion along the surrounding filaments. Methods: We analyzed data from two-pointed Suzaku observations of A2744 to derive the temperature distribution out to the virial radius in three different directions. We also performed a deprojection analysis to study radial profiles of gas temperature, density, and entropy and compared the X-ray results with multi-wavelength data to investigate correlations with the surface density of galaxies and with radio relics. Results: The gas temperature was measured out to the virial radius $r_{200}$ in the north-east region and to about $1.5r_{200}$ in the north-west and south regions. The radial profile of the gas temperature is rather flat and the temperature is very high (even near $r_{200}$); it is comparable to the mean temperature of this cluster ($kT=9$ keV). These characteristics have not been reported in any other cluster. We find a hint of temperature jump in the northeast region whose location coincides with a large radio relic, indicating that the cluster experienced gas heating because of merger or mass accretion onto the main cluster. The temperature distribution is anisotropic and shows no clear positive correlation with the galaxy density, which suggests an inhomogeneous mass structure and a complex merger history in A2744.
Finding an unsupervised decomposition of an image into individual objects is a key step to leverage compositionality and to perform symbolic reasoning. Traditionally, this problem is solved using amortized inference, which does not generalize beyond the scope of the training data, may sometimes miss correct decompositions, and requires large amounts of training data. We propose finding a decomposition using direct, unamortized optimization, via a combination of a gradient-based optimization for differentiable object properties and global search for non-differentiable properties. We show that using direct optimization is more generalizable, misses fewer correct decompositions, and typically requires less data than methods based on amortized inference. This highlights a weakness of the current prevalent practice of using amortized inference that can potentially be improved by integrating more direct optimization elements.
The space-based gravitational wave detector LISA will observe in the low-frequency gravitational-wave band (0.1 mHz up to 1 Hz). LISA will search for a variety of expected signals, and when it detects a signal it will have to determine a number of parameters, such as the location of the source on the sky and the signal's polarisation. This requires pattern-matching, called matched filtering, which uses the best available theoretical predictions about the characteristics of waveforms. All the estimates of the sensitivity of LISA to various sources assume that the data analysis is done in the optimum way. Because these techniques are unfamiliar to many young physicists, I use the first part of this lecture to give a very basic introduction to time-series data analysis, including matched filtering. The second part of the lecture applies these techniques to LISA, showing how estimates of LISA's sensitivity can be made, and briefly commenting on aspects of the signal-analysis problem that are special to LISA.
We consider stochastic partial differential equations on $\mathbb{R}^{d}, d\geq 1$, driven by a Gaussian noise white in time and colored in space, for which the pathwise uniqueness holds. By using the Skorokhod representation theorem we establish various strong stability results. Then, we give an application to the convergence of the Picard successive approximation. Finally, we show that in the sense of Baire category, almost all stochastic partial differential equations with continuous and bounded coefficients have the properties of existence and uniqueness of solutions as well as the continuous dependence on the coefficients.
Velocities in stable circular orbits about galaxies, a measure of centripetal gravitation, exceed the expected Kepler/Newton velocity as orbital radius increases. Standard LCDM attributes this anomaly to galactic dark matter. McGaugh et al have recently shown for 153 disc galaxies that observed radial acceleration is an apparently universal function of classical acceleration computed for observed galactic baryonic mass density. This is consistent with the empirical MOND model, not requiring dark matter. It is shown here that suitably constrained LCDM and conformal gravity (CG) also produce such a universal correlation function. LCDM requires a very specific dark matter distribution, while the implied CG nonclassical acceleration must be independent of galactic mass. All three constrained radial acceleration functions agree with the empirical baryonic $v^4$ Tully-Fisher relation. Accurate rotation data in the nominally flat velocity range could distinguish between MOND, LCDM, and conformal gravity.
The field inside a Casimir cavity has an effective negative mass, which acts as a buoyancy force in a gravitational field. Can this render the total mass of the cavity negative, making it "float" in the vacuum ? Recent theoretical arguments indicate that this is impossible. We provide support to this conclusion discussing a concrete simple model of cavity, with plane parallel metallic plates kept in mechanical equilibrium by a spring and placed in a weak gravitational field. We show that basic facts about the structure of matter imply that the total mass of the cavity is always positive. This has implications for the hypothetical relation between vacuum energy and cosmological constant.
Although general relativity (GR) passes all present experimental tests with flying colors, it remains important to study alternative theories of gravity for several theoretical and phenomenological reasons that we recall in these lecture notes. The various possible ways of modifying GR are presented, and we notably show that the motion of massive bodies may be changed even if one assumes that matter is minimally coupled to the metric as in GR. This is illustrated with the particular case of scalar-tensor theories of gravity, whose Fokker action is discussed, and we also mention the consequences of the no-hair theorem on the motion of black holes. The finite size of the bodies modifies their motion with respect to pointlike particles, and we give a simple argument showing that the corresponding effects are generically much larger in alternative theories than in GR. We also discuss possible modifications of Newtonian dynamics (MOND) at large distances, which have been proposed to avoid the dark matter hypothesis. We underline that all the previous classes of alternatives to GR may a priori be used to predict such a phenomenology, but that they generically involve several theoretical and experimental difficulties.
We calculate the tropical Dolbeault cohomology for the analytifications of the projective line and Mumford curves over non-archimedean fields. We show that the cohomology satisfies Poincar\'e duality and behaves analogously to the cohomology of curves over the complex numbers. Further, we give a complete calculation of the dimension of the cohomology on a basis of the topology.
It is well known that the product of two independent regularly varying random variables with the same tail index is again regularly varying with this index. In this paper, we provide sharp sufficient conditions for the regular variation property of product-type functions of regularly varying random vectors, generalizing and extending the univariate theory in various directions. The main result is then applied to characterize the regular variation property of products of iid regularly varying quadratic random matrices and of solutions to affine stochastic recurrence equations under non-standard conditions.
In this article our main result is a more complete version of the statements obtained in {\rm [6]}. One of the important technical point of our proof is an $\displaystyle L^{2\over m}$ extension theorem of Ohsawa-Takegoshi type, which is derived from the original result by a simple fixed point method. Moreover, we show that these techniques combined with an appropriate form of the"invariance of plurigenera" can be used in order to obtain a new proof of the celebrated Y. Kawamata subadjunction theorem.
We study a strongly Non-Markovian variant of random walk in which the probability of visiting a given site $i$ is a function $f$ of number of previous visits $v(i)$ to the site. If the probability is proportional to number of visits to the site, say $f(i)=(v(i)+1)^{\alpha}$ the probability distribution of visited sites tends to be flat for ${\alpha}>0$ compared to simple random walk. For $f(i)=e^{-v(i)}$, we observe a distribution with two peaks. The origin is no longer the most probable site. The probability is maximum at site k(t) which increases in time. For $f(i)=e^{-v(i)}$ and for ${\alpha}>0$ the properties do not change as the walk ages. However, for ${\alpha}<0$, the properties are similar to simple random walk asymptotically. We study lattice covering time for these functions. The lattice covering time scales as $N^{z}$, with $z=2$, for ${\alpha} \le 0$, $z>2$ for ${\alpha} >0$ and $z<2$ for $f(i)=e^{-v(i)}$.
The most general evolution of the density matrix of a quantum system with a finite-dimensional state space is by stochastic maps which take a density matrix linearly into the set of density matrices. These dynamical stochastic maps form a linear convex set that may be viewed as supermatrices. The property of hermiticity of density matrices renders an associated supermatrix hermitian and hence diagonalizable. The positivity of the density matrix does not make the associated supermatrix positive though. If the map itself is positive, it is called completely positive and they have a simple parameterization. This is extended to all positive (not completely positive) maps. A general dynamical map that does not preserve the norm of the density matrices it acts on can be thought of as the contraction of a norm-preserving map of an extended system. The reconstruction of such extended dynamics is also given.
In the evolutionary version of the minority game, agents update their strategies (gene-value $p$) in order to improve their performance. Motivated by recent intriguing results obtained for prize-to-fine ratios which are smaller than unity, we explore the system's dynamics with a strategy updating rule of the form $p \to p \pm \delta p$ ($0 \leq p \leq 1$). We find that the strategy distribution depends strongly on the values of the prize-to-fine ratio $R$, the length scale $\delta p$, and the type of boundary condition used. We show that these parameters determine the amplitude and frequency of the the temporal oscillations observed in the gene space. These regular oscillations are shown to be the main factor which determines the strategy distribution of the population. In addition, we find that agents characterized by $p={1 \over 2}$ (a coin-tossing strategy) have the best chances of survival at asymptotically long times, regardless of the value of $\delta p$ and the boundary conditions used.
Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum analogue, or inverse-volume corrections coming from the eigenvalues of the inverse-volume operator.   In this paper we will develop an alternative approach to calculate cosmological perturbations in LQC based on the fact that, holonomy corrected LQC in the flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) geometry could be also obtained as a particular case of teleparallel $F(T)$ gravity (teleparallel LQC). The main idea of our approach is to mix the simple bounce provided by holonomy corrections in LQC with the non-singular perturbation equations given by $F(T)$ gravity, in order to obtain a matter bounce scenario as a viable alternative to slow-roll inflation.   In our study, we have obtained an scale invariant power spectrum of cosmological perturbations. However, the ratio of tensor to scalar perturbations is of order $1$, which does not agree with the current observations. For this reason, we suggest a model where a transition from the matter domination to a quasi de Sitter phase is produced in order to enhance the scalar power spectrum.
In these lecture notes for the Les Houches School on Applications of Random Matrices in Physics we give an introduction to the connections between matrix models and topological strings. We first review some basic results of matrix model technology and then we focus on type B topological strings. We present the main results of Dijkgraaf and Vafa describing the spacetime string dynamics on certain Calabi-Yau backgrounds in terms of matrix models, and we emphasize the connection to geometric transitions and to large N gauge/string duality. We also use matrix model technology to analyze large N Chern-Simons theory and the Gopakumar-Vafa transition.
Magnetoelastic and magnetoelectric coupling in the artificial multiferroic heterostructures facilitate valuable features for device applications such as magnetic field sensors and electric write magnetic-read memory devices. In a ferromagnetic/ferroelectric heterostructures, the strain mediated coupling exploits piezoelectricity/electrostriction in ferroelectric phase and magnetostriction/piezomagnetism in ferromagnetic phase. Such verity of these combined effect can be manipulated by an external perturbation, such as electric field, temperature or magnetic field. Here, we demonstrate the remote-controlled tunability of these effects under the visible, coherent and polarized light. The combined surface and bulk magnetic study of domain-correlated Ni/BaTiO3 heterostructure reveals that the system is strong sensitive about the light illumination via the combined effect of converse piezoelectric, magnetoelastic coupling and converse magnetostriction. Well-defined ferroelastic domain structure is fully transferred from a tetragonal ferroelectric to magnetostrictive layer via interface strain transfer during the film growth. The visible light illumination is used to manipulate the original ferromagnetic microstructure by the light-induced domain wall motion in ferroelectric, consequently the domain wall motion in the ferromagnetic layer. Our findings mimic the attractive remote-controlled ferroelectric random-access memory write and magnetic random-access memory read application scenarios, hence, can be proven as a novel perspective for room temperature device applications.
We study cup products in integral cohomology of the Hilbert scheme of $n$ points on a K3 surface and present a computer program for this purpose. In particular, we deal with the question, which classes can be represented by products of lower degrees.
Results from various theoretical approaches and ideas presented at this exciting meeting are reviewed. I also point towards future directions, in particular hydrodynamic behaviour induced by jets traveling through the quark-gluon plasma, which might be worth looking at in more detail.
The study of quasi-periodic oscillations (QPOs) of X-ray flux observed in many microquasars can provide a powerful tool for testing of the phenomena occurring in strong gravity regime. QPOs phenomena can be well related to the oscillations of charged particles in accretion disks orbiting Kerr black holes immersed in external large-scale magnetic fields. In the present paper we study the model of magnetic relativistic precession and provide estimations of the mass and spin of the central object of the microquasar H~1743-322 which is a candidate for a black hole. Moreover, we discuss the possible values of external magnetic field and study its influence on the motion of charged particles around rotating black hole.
In this paper we study the holographic dual, in several spacetime dimensions, of the Higgs branch of gauge theories with fundamental matter. These theories contain defects of various codimensionalities, where the matter fields are located. In the holographic description the matter is added by considering flavor brane probes in the supergravity backgrounds generated by color branes, while the Higgs branch is obtained when the color and flavor branes recombine with each other. We show that, generically, the holographic dual of the Higgs phase is realized by means of the addition of extra flux on the flavor branes and by choosing their appropriate embedding in the background geometry. This suggests a dielectric interpretation in terms of the color branes, whose vacuum solutions precisely match the F- and D-flatness conditions obtained on the field theory side. We further compute the meson mass spectra in several cases and show that when the defect added has codimension greater than zero it becomes continuous and gapless.
The recently discovered three-dimensional hyperhoneycomb iridate, $\beta$-Li$_2$IrO$_3$, has raised hopes for the realization of dominant Kitaev interaction between spin-orbit entangled local moments due to its near-ideal lattice structure. If true, this material may lie close to the sought-after quantum spin liquid phase in three dimensions. Utilizing ab-initio electronic structure calculations, we first show that the spin-orbit entangled basis, $j_{\rm eff}$=1/2, correctly captures the low energy electronic structure. The effective spin model derived in the strong coupling limit supplemented by the ab-initio results is shown to be dominated by the Kitaev interaction. We demonstrated that the possible range of parameters is consistent with a non-coplanar spiral magnetic order found in a recent experiment. All of these analyses suggest that $\beta$-Li$_2$IrO$_3$ may be the closest among known materials to the Kitaev spin liquid regime.
According to standard cosmology, the universe is homogeneous and isotropic at large scales. However, some anisotropies can be observed at the local scale in the universe through various ways. Here we have studied the Bianchi type I model with customizing the scale factors to understand the anisotropic nature of the universe. We have considered two cases with slight modifications of scale factors in different directions in the generalized Bianchi Type I metric equation, and compared the results with the $\Lambda$CDM model and also with available cosmological observational data. Through this study, we also want to predict the possible degree of anisotropy present in the early universe and its evolution to current time by calculating the value of density parameter for anisotropy ($\Omega_{\sigma}$) for both low and high redshift (z) along with the possible relative anisotropy that exist among different directions. It is found that there was a significant amount of anisotropy in the early universe and the anisotropic nature of the universe vanishes at the near past and the present epochs. Thus at near past and present stages of the universe there is no effective distinction between this anisotropic model and the standard $\Lambda$CDM model.
This paper investigates the visual quality of the adversarial examples. Recent papers propose to smooth the perturbations to get rid of high frequency artefacts. In this work, smoothing has a different meaning as it perceptually shapes the perturbation according to the visual content of the image to be attacked. The perturbation becomes locally smooth on the flat areas of the input image, but it may be noisy on its textured areas and sharp across its edges.   This operation relies on Laplacian smoothing, well-known in graph signal processing, which we integrate in the attack pipeline. We benchmark several attacks with and without smoothing under a white-box scenario and evaluate their transferability. Despite the additional constraint of smoothness, our attack has the same probability of success at lower distortion.
Advances in understanding of the white light faculae measured at the Royal Greenwich Observatory from 1874 to 1976 suggest that they offer a more direct measure of solar brightening by small diameter photospheric magnetic flux tubes than do chromospheric proxies. Proxies such as the area of Ca K plages, the Mg index or the microwave flux include many dark photospheric structures as well as pores and sunspots. Our reconstruction of variation in total solar irradiance,TSI,based on the faculae indicates that the sun dimmed by almost 0.1 percent in the mid- twentieth century rather than brightening as represented in previous reconstructions. This dimmimg at the sun's highest activity level since the seventeenth century is consistent with the photometric behavior observed in somewhat younger sun like stars. The prolonged TSI decrease may have contributed more to the cooling of climate between about 1940 and 1970 than present models indicate.
The chain covering number $\Cov(P)$ of a poset $P$ is the least number of chains needed to cover $P$. For a cardinal $\nu$, we give a list of posets of cardinality and covering number $\nu$ such that for every poset $P$ with no infinite antichain, $\Cov(P)\geq \nu$ if and only if $P$ embeds a member of the list. This list has two elements if $\nu$ is a successor cardinal, namely $[\nu]^2$ and its dual, and four elements if $\nu$ is a limit cardinal with $\cf(\nu)$ weakly compact. For $\nu= \aleph_1$, a list was given by the first author; his construction was extended by F. Dorais to every infinite successor cardinal $\nu$.