ShantanuT01/DACTYL-Pretraining huggingface dataset:
The X-ray emission from a simulated massive stellar cluster is investigated. The emission is calculated from a 3D hydrodynamical model which incorporates the mechanical feedback from the stellar winds of 3 O-stars embedded in a giant molecular cloud clump containing 3240 M$_{\odot}$ of molecular material within a 4 pc radius. A simple prescription for the evolution of the stars is used, with the first supernova explosion at t=4.4 Myrs. We find that the presence of the GMC clump causes short-lived attenuation effects on the X-ray emission of the cluster. However, once most of the material has been ablated away by the winds the remaining dense clumps do not have a noticable effect on the attenuation compared with the assumed interstellar medium column. We determine the evolution of the cluster X-ray luminosity, L$_X$, and spectra, and generate synthetic images. The intrinsic X-ray luminosity drops from nearly 10$^{34}$ ergs s$^{-1}$ while the winds are `bottled up', to a near constant value of 1.7$\times 10^{32}\rm ergs s^{-1}$ between t=1-4 Myrs. L$_X$ reduces slightly during each star's red supergiant stage due to the depressurization of the hot gas. However, L$_X$ increases to $\approx 10^{34}\rm\,ergs s^{-1}$ during each star's Wolf-Rayet stage. The X-ray luminosity is enhanced by 2-3 orders of magnitude to $\sim 10^{37}\rm ergs s^{-1}$ for at least 4600 yrs after each supernova, at which time the blast wave leaves the grid and the X-ray luminosity drops. The X-ray luminosity of our simulation is generally considerably fainter than predicted from spherically-symmetric bubble models, due to the leakage of hot gas material through gaps in the outer shell. This process reduces the pressure within our simulation and thus the X-ray emission. However, the X-ray luminosities and temperatures which we obtain are comparable to similarly powerful massive young clusters.
We present the analysis of new, deep HI observations of the spiral galaxy NGC 3198, as part of the HALOGAS (Westerbork Hydrogen Accretion in LOcal GAlaxieS) survey, with the main aim of investigating the presence, amount, morphology and kinematics of extraplanar gas. We present models of the HI observations of NGC 3198: the model that matches best the observed data cube features a thick disk with a scale height of ~3 kpc and an HI mass of about 15% of the total HI mass; this thick disk also has a decrease in rotation velocity as a function of height (lag) of 7-15 km/s/kpc (though with large uncertainties). This extraplanar gas is detected for the first time in NGC 3198. Radially, this gas appears to extend slightly beyond the actively star-forming body of the galaxy (as traced by the Halpha emission), but it is not more radially extended than the outer, fainter parts of the stellar disk. Compared to previous studies, thanks to the improved sensitivity we trace the rotation curve out to larger radii. We model the rotation curve in the framework of MOND (Modified Newtonian Dynamics) and we confirm that, with the allowed distance range we assumed, fit quality is modest in this galaxy, but the new outer parts are explained in a satisfactory way.
We consider the one-dimensional generalized forest fire process: at each site of $\zz$, seeds and matches fall according some i.i.d. stationary renewal processes. When a seed falls on an empty site, a tree grows immediately. When a match falls on an occupied site, a fire starts and destroys immediately the corresponding connected component of occupied sites. Under some quite reasonable assumptions on the renewal processes, we show that when matches become less and less frequent, the process converges, with a correct normalization, to a limit forest fire model. According to the nature of the renewal processes governing seeds, there are four possible limit forest fire models. The four limit processes can be perfectly simulated. This study generalizes consequently a previous result of the authors where seeds and matches were assumed to fall according to Poisson processes.
We have used observations gathered at CTIO to measure distances by the Expanding Photosphere Method (EPM) to 5 Type II supernovae. These supernovae lie at redshifts from cz = 1100 km/s to z = 5500 km/s, and increase to 18 the number of distances measured using EPM. We compare distances derived to 11 Type II supernovae with distances to their host galaxies measured using the Tully-Fisher method. We find that the Tully-Fisher distances average 11%+-7% smaller. The comparison shows no significant evidence of any large distance-dependent bias in the Tully-Fisher distances. We employ the sample of EPM distances from 4.5~Mpc to 180~Mpc to derive a value for the Hubble Constant. We find H_0 = 73 +- 6 (statistical) +- 7 (systematic}) km/s/Mpc.
Based on a single particle model which describes the time evolution of the wave function during tunneling across a one dimensional potential barrier we study the proton decay of $^{208}$Pb from excited states with non-vanishing angular momentum $\ell$. Several quantities of interest in this process like the decay rate $\lambda$, the period of oscillation $T_{osc}$, the transient time $t_{tr}$, the tunneling time $t_{tun}$ and the average value of the proton packet position $ r_{av} $ are computed and compared with the WKB results.
A second-order expansion for the quantum fluctuations of the matter field was considered in the framemork of the warm inflation scenario. The friction and Hubble parameters were expanded by means of a semiclassical approach. The fluctuations of the Hubble parameter generates fluctuations of the metric. These metric fluctuations produce an effective term of curvature. The power spectrum for the metric fluctuations can be calculated on the infrared sector.
The GMRT Epoch of Reionization (EoR) experiment is an ongoing effort to measure the power spectrum from neutral hydrogen at high redshift. We have previously reported an upper limit of (70 mK)^2 at wavenumbers of k=0.65 h/Mpc using a basic piecewise-linear foreground subtraction. In this paper we explore the use of a singular value decomposition to remove foregrounds with fewer assumptions about the foreground structure. Using this method we also quantify, for the first time, the signal loss due to the foreground filter and present new power spectra adjusted for this loss, providing a revised measurement of a 2-sigma upper limit at (248 mK)^2 for k=0.50 h/Mpc. While this revised limit is larger than previously reported, we believe it to be more robust and still represents the best current constraints on reionization at z=8.6.
H3LiIr2O6 is the first honeycomb-lattice system without any signs of long-range magnetic order down to the lowest temperatures, raising the hope for the realization of an ideal Kitaev quantum spin liquid. Its honeycomb layers are coupled by interlayer hydrogen bonds. Static or dynamic disorder of these hydrogen bonds was proposed to strongly affect the magnetic exchange and to make Kitaev-type interactions dominant. Using dielectric spectroscopy, here we provide experimental evidence for dipolar relaxations in H3LiIr2O6 and deuterated D3LiIr2O6, which mirror the dynamics of protons and deuterons within the double-well potentials of the hydrogen bonds. The detected hydrogen dynamics reveals glassy freezing, characterized by a strong slowing down under cooling, with a crossover from thermally-activated hopping to quantum-mechanical tunneling towards low temperatures. Thus, besides being Kitaev quantum-spin-liquid candidates, these materials also are quantum paraelectrics. However, the small relaxation rates in the mHz range, found at low temperatures, practically realize quasi-static hydrogen disorder, as assumed in recent theoretical works to explain the quantum-spin-liquid ground state of both compounds.
A technique for the reconstruction of the potential for a scalar field in cosmological models based on induced gravity has recently been developed by Alexander Y. Kamenshchik, Alessandro Tronconi, and Giovanni Venturi \cite{ref1}. In this paper, this extended reconstruction method is utilized to investigate the nature of the scalar potentials of the most extended action of $F(T)$-gravity context. First, a general formalism is formulated and then it is utilized for considering some well-known special cases including `Barotropic Fluid', `Cosmological Constant', and `Modified Chaplygin Gas'. The analysis of the results is carried out by the use of the $\mathfrak{B}\text{-function}$ method which has recently been suggested by the author. As we know, assuming a proportional relation between the scale factor of the $x\text{-direction}$ and the scale factors of $y$ and $z$ directions (i.e. $A=B^{m}$) in dealing with LRS Bianchi-I background is prevalent. Pursuant to observational data, the correct physical range of $m$ is extracted. It is demonstrated that, unlike several papers, $m$ is very close to $1$. Some interesting discussions about the modified and generalized Chaplygin gases are performed. The ranges of the amounts of free parameters of the various types of Chaplygin gases are corrected according to observational data. It is demonstrated that the generalized Chaplygin gas model namely $P=-\sigma_{2}/\rho^{\nu}$ may be developed as $P=-\sigma_{2}/\rho^{\nu(t)}$ (i.e. $\nu=const. \longrightarrow \nu=\nu(t)$). Ultimately, by combining ref. \cite{ref1} and the current paper, a general prescription is recommended for the reconstruction of the potentials of alternative theories of gravity (especially $F(R)$ and $F(T)$), and their relevant analysis.
Building on the five-dimensional constructions in hep-th/0601177, we provide a unified description of four-dimensional N = 2 superconformal off-shell multiplets in projective superspace, including a realization in terms of N = 1 superfields. In particular, superconformal polar multiplets are consistently defined for the first time. We present new 4D N = 2 superconformal sigma-models described by polar multiplets. Such sigma-models realize general superconformal couplings in projective superspace, but involve an infinite tale of auxiliary N = 1 superfields. The auxiliaries should be eliminated by solving infinitely many algebraic nonlinear equations, and this is a nontrivial technical problem. We argue that the latter can be avoided by making use of supersymmetry considerations. All information about the resulting superconformal model (and hence the associated superconformal cone) is encoded in the so-called canonical coordinate system for a Kaehler metric, which was introduced by Bochner and Calabi in the late 1940s.
We present SCUBA-2 850-$\mu$m observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850-$\mu$m sources in 9/13 of these candidate protoclusters show significant overdensities compared to the field, with the probability $<$10$^{-2}$ assuming the sources are randomly distributed in the sky. Using the 250-, 350-, 500- and 850-$\mu$m flux densities, we estimate the photometric redshifts of individual SCUBA-2 sources by fitting spectral energy distribution (SED) templates with an MCMC method. The photometric redshift distribution, peaking at $2<z<3$, is consistent with that of known $z>2$ protoclusters and the peak of the cosmic star-formation rate density (SFRD). We find that the 850-$\mu$m sources in our candidate protoclusters have infrared luminosities of $L_{\mathrm{IR}}\gtrsim$10$^{12}L_{\odot}$ and star-formation rates of SFR=(500-1,500)$M_{\odot}$yr$^{-1}$. By comparing with results in the literature considering only Herschel photometry, we conclude that our 13 candidate protoclusters can be categorised into four groups: six of them being high-redshift starbursting protoclusters, one being a lower-redshift cluster/protocluster, three being protoclusters that contain lensed DSFG(s) or are rich in 850-$\mu$m sources, and three regions without significant Herschel or SCUBA-2 source overdensities. The total SFRs of the candidate protoclusters are found to be comparable or higher than those of known protoclusters, suggesting our sample contains some of the most extreme protocluster population. We infer that cross-matching Planck and Herschel data is a robust method for selecting candidate protoclusters with overdensities of 850-$\mu$m sources.
We construct an independent increments Gaussian process associated to a class of multicolor urn models. The construction uses random variables from the urn model which are different from the random variables for which central limit theorems are available in the two color case.
Low-alloy steels are constituted of twenty-four variants of lath martensite that exhibit gradients of orientations from Kurdjumov-Sachs (KS) to Nishiyama-Wassermann (NW). They are structured into four packets on each of the common close-packed plane {111}fcc// {110}bcc; and each packet is composed of three blocks constituted by pairs of low-misoriented variants. The habit planes reported in literature for this type of martensite are {557}fcc, but it is not clear whether they correspond to the laths or to the blocks. In this paper, we present crystallographic calculations proving that the average of the two KS distortions associated with the variants in a block is exactly a NW distortion. A new method of averaging distortion matrices was introduced for this purpose. It is also shown that the {575}fcc planes are let untilted by this NW distortion, and are thus good theoretical candidates for the observed habit planes. The predicted {575}fcc planes, however, do not contain any of the common close-packed directions of the two variants in the block, which is in apparent contradiction with the current view. In order to clarify this point, some Electron BackScatter Diffraction (EBSD) maps were acquired on different low-carbon steels; the prior austenitic grains were automatically reconstructed and the traces of the habit planes predicted by the different models were analyzed and compared to the morphologies. This experimental work shows that {575}fcc planes are the habit plane of the blocks, and that the habit plane of one block often dominates the others, which impedes to discriminate the different models. The advantages of our model are its simplicity, the absence of fitting parameters, and the symmetric role played by the variants the blocks.
The stellar content of the nearby SB(s)m galaxy NGC 55 is investigated using images covering the visible and near-infrared wavelength regions. A well-defined plume, which stellar evolution models suggest contains stars with masses near the RSG - AGB transition, is detected in CMDs of the disk, and it is concluded that star formation in the thin disk of NGC 55 has ocurred at a significant rate for at least the past 0.1 - 0.2 Gyr. The disk also contains a large population of old (log(t_yr) ~ 10) stars, and it is argued that a stable disk has been in place in NGC 55 for a significant fraction of the age of the Universe. At projected distances in excess of 2 kpc off of the disk plane the brightest AGB stars have ages 10(+3)(-2) Gyr. Thus, despite indications that dust and gas are present in the envelope surrounding the NGC 55 disk, the AGB content suggests that recently formed stars do not occur in large numbers in the extraplanar region. The mean metallicity of extraplanar RGB stars is in excellent agreement with that measured in the extraplanar HII regions EHR 1 and 2, suggesting that the age-metallicity relation in this part of NGC 55 has been flat for at least a few Gyr. Finally, the RGB-tip occurs near i' = 23.1 in the extraplanar region, and a distance modulus of 26.5 is computed from this feature.
We study the isoperimetric and spectral profiles of certain families of finitely generated groups defined via actions on labelled Schreier graphs and simple {\em gluing} of such. In one of our simplest constructions---the {\em pocket-extension} of a group $G$---this leads to the study of certain finitely generated subgroups of the full permutation group $\mathbb S(G\cup \{*\})$. Some sharp estimates are obtained while many challenging questions remain.
Abnormal grain growth (AGG) was observed in rutile TiO2 formed by the thermal treatment of anatase TiO2 in the presence of zirconium silicate. This morphological behaviour was seen to occur in sintered powder compacts and thin films with solid state zircon dopants and in TiO2 coatings on grains of zircon sand. In order to clarify the mechanism of AGG in this system, various doping methods were employed and the morphological consequences of these doping methods were investigated. It was found that doping by Zr and Si does not give rise to abnormal grain growth. The observed phenomena were discussed in terms of morphological and energetic considerations. It is likely that a distinct orientation relationship between rutile TiO2 and ZrSiO4 and possible grain boundary liquid formation play a role in giving rise to the rapid growth of faceted prismatic rutile.
In the broken-symmetry phase of the electroweak theory there is no unique definition of the electromagnetic field tensor in cases where the magnitude of the Higgs field differs from a constant value. The meaning of the electromagnetic field is therefore dubious near defects and during non-equilibrium stages of the electroweak phase transition. Nevertheless, by imposing a minimal set of natural requirements one is led to a specific, gauge-invariant definition that retains the familiar properties of an electromagnetic field. An electromagnetic vector potential is constructed whose curl (exterior derivative) in any gauge gives the electromagnetic field tensor. As is required, this vector potential transforms at most by a pure gradient under arbitrary SU(2)xU(1) gauge transformations. The flux of the magnetic field is expressed as a gauge-invariant line integral. Curiously, this provides a definition for magnetic flux in cases where the spatial region with broken symmetry is not simply connected and the magnetic field itself is not everywhere defined.
A derivation is given of the Boltzmann-Vlasov equation beginning from multiple scattering considerations. The motivation for the discussion, which is purely pedagogical in nature, is the current interest in understanding the origins of transport equations in terms of rigorous field-theory descriptions, or, as in this case, exact nonrelativistic formulations.
We prove that for any integer $k\geq 2$ and $\varepsilon>0$, there is an integer $\ell_0\geq 1$ such that any $k$-uniform hypergraph on $n$ vertices with minimum codegree at least $(1/2+\varepsilon)n$ has a fractional decomposition into tight cycles of length $\ell$ ($\ell$-cycles for short) whenever $\ell\geq \ell_0$ and $n$ is large in terms of $\ell$. This is essentially tight.   This immediately yields also approximate integral decompositions for these hypergraphs into $\ell$-cycles. Moreover, for graphs this even guarantees integral decompositions into $\ell$-cycles and solves a problem posed by Glock, K\"uhn and Osthus. For our proof, we introduce a new method for finding a set of $\ell$-cycles such that every edge is contained in roughly the same number of $\ell$-cycles from this set by exploiting that certain Markov chains are rapidly mixing.
It is shown that the graph obtained by merging two vertices of two 4-cycles is not a $\Theta$-graceful partial cube, thus answering in the negative a question by Bre\v{s}ar and Klav\v{z}ar from [1], who asked whether every partial cube is $\Theta$-graceful.
The present paper is dedicated to the large time asymptotic behavior of global strong solutions near constant equilibrium (away from vacuum) to the compressible Navier-Stokes-Poisson equations. Precisely, we present that under the same regularity assumptions as in \cite{SX2}, a \textit{different} time-decay framework of the $\dot{B}_{p,1}^{s}$ norm of the critical global solutions is established. The proof mainly depends on the pure energy argument \textit{without the spectral analysis}, which allows us to remove \textit{the usual smallness assumption of low frequencies of initial data}.
We report soft point-contact spectroscopy studies of URu2Si2 both in the hidder order (HO) and the large-moment antiferromagnetic (LMAF) states accessed by pressure. In the HO state at ambient pressure, the spectroscopy shows two asymmetric peaks around the Fermi energy that emerge below the hidden order temperature T_{HO}. In the LMAF state at higher pressures, the spectra are remarkably similar to those in the HO state, indicating a similar Fermi surface gapping in the HO and LMAF states and providing a new clue to unraveling the puzzling HO state.
$\Omega_b \rightarrow \Omega_c^{(*)}$ semi-leptonic decays are studied in details. Relevant helicity amplitudes are written down. Both unpolarized and polarized $\Omega_b$ cases are considered. Decay angular distributions, asymmetry parameters and semileptonic decay rates are calculated, with numerical results using leading order results of the large $N_c$ and heavy quark effective theory(HQET).
One cannot yet point to any firm string prediction. While many approximate string ground states are known with interesting properties, we do not have any argument that one or another describes what we observe around us, and for reasons which appear fundamental we do not know how to systematically determine even any rough quantitative properties. I argue here that we should examine large classes of string ground states, trying to determine whether features such as low energy supersymmetry, the pattern of supersymmetry breaking, the presence of axions, large dimensions, or others might be generic.
The $TH\epsilon\mu$ formalism was developed to study nonmetric theories of gravitation. In this letter we show that theories that violate Local Lorentz Invariance (LLI) or Local Position Invariance (LPI) also violate charge conservation. Using upper bounds on this violation we can put very stringent limits to violations of Einstein Equivalence Principle (EEP). These limits, in turn, severely restrict string-based models of low energy physics.
It is shown that the long-standing puzzle of incommensurate crystal structure of AuTe$_2$ can be solved, if this material is considered as a negative charge-transfer system. Using modern computational methods, we demonstrate that charge redistribution associated with incommensurate modulations of crystal structure occurs not so much on Au, but predominantly on Te sites. This substantially reduces Coulomb energy costs for creating such a unique crystal structure. The same mechanism also explains superconductivity of doped AuTe$_2$. Exploring different Au-Te compositions, we also discovered a previously unknown compound AuTe, which theoretically is very stable, and we predict its crystal structure.
For a generalized continuous state branching process with non-vanishing diffusion part, finite expectation and a directed ("left-to-right") interaction, we construct the height process of its forest of genealogical trees. The connection between this height process and the population size process is given by an extension of the second Ray--Knight theorem. This paper generalizes earlier work of the two last authors which was restricted to the case of continuous branching mechanisms. Our approach is different from that of Berestycki et al. There the diffusion part of the population process was allowed to vanish, but the class of interactions was more restricted.