ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present a comparison of Spitzer IRS data for 51 OH megamaser (OHM) hosts and 15 non-masing ULIRGs. 10-25% of OHMs show evidence for the presence of an AGN, significantly lower than the estimated AGN fraction from previous optical and radio studies. Non-masing ULIRGs have a higher AGN fraction (50-95%) than OHMs, although some galaxies in both samples show evidence of co-existing starbursts and AGN. Radiative transfer models of the dust environment reveal that non-masing galaxies tend to have clumpy dust geometries commonly associated with AGN, while OHMs have deeper absorption consistent with a smooth, thick dust shell. Statistical analyses show that the major differences between masing and non-masing ULIRGs in the mid-IR relate to the optical depth and dust temperature, which we measure using the 9.7 um silicate depth and 30-20 um spectral slope from the IRS data. Dust temperatures of 40-80 K derived from the IRS data are consistent with predictions of OH pumping models and with a minimum T_dust required for maser production. The best-fit dust opacities ({\tau}_V ~ 100 - 400), however, are nearly an order of magnitude larger than those predicted for OH inversion, and suggest that modifications to the model may be required. These diagnostics offer the first detailed test of an OHM pumping model based only on the properties of its host galaxy and provide important restrictions on the physical conditions relevant to OHM production.
We discover a late-type L dwarf, WISEP J060738.65+242953.4 (W0607+2429), by comparing the Wide-field Infrared Survey Explorer (WISE) preliminary data release to the Two Micron All Sky Survey (2MASS) in search of high proper motion objects (>0.3" yr^-1). W0607+2429 was found to have a proper motion of 0.57 +/- 0.02" yr^-1. Based on colors and color-color diagrams using 2MASS and Sloan Digital Sky Survey (SDSS) photometry, we estimate the spectral type (optical) to be L8 within a spectral sub-type. Based on the spectral type estimated we find W0607+2429 to have a distance of 7.8^(+1.4)_(-1.2) pc, making it one of only four very-late L dwarfs within 10 pc, and the third closest L dwarf overall. This close L/T transition dwarf will play a pivotal role in resolving outstanding issues of condensate clouds of low temperature atmospheres.
We show that the inclusion of counter-rotating terms, usually dropped in evaluations of interaction of an electric dipole of a two level atom with the electromagnetic field, leads to significant modifications of trapping potential in the case of large detuning. The results are shown to be in excellent numerical agreement with recent experimental findings, for the case of modes of Laguerre-Gauss spatial profile.
We consider a branching-selection particle system on the real line. In this model the total size of the population at time $n$ is limited by $\exp\left(a n^{1/3}\right)$. At each step $n$, every individual dies while reproducing independently, making children around their current position according to i.i.d. point processes. Only the $\exp\left(a(n+1)^{1/3}\right)$ rightmost children survive to form the $(n+1)^\mathrm{th}$ generation. This process can be seen as a generalisation of the branching random walk with selection of the $N$ rightmost individuals, introduced by Brunet and Derrida. We obtain the asymptotic behaviour of position of the extremal particles alive at time $n$ by coupling this process with a branching random walk with a killing boundary.
While the evolution of superbubbles driven by clustered supernovae has been studied by numerous authors, the resulting radial momentum yield is uncertain by as much as an order of magnitude depending on the computational methods and assumed properties of the surrounding interstellar medium (ISM). In this work, we study the origin of these discrepancies, and seek to determine the correct momentum budget for a homogeneous ISM. We carry out 3D hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations of clustered supernova explosions, using a Lagrangian method and checking for convergence with respect to resolution. We find that the terminal momentum of a shell driven by clustered supernovae is dictated primarily by the mixing rate across the contact discontinuity between the hot and cold phases, and that this energy mixing rate is dominated by numerical diffusion even at the highest resolution we can complete, 0.03 $M_\odot$. Magnetic fields also reduce the mixing rate, so that MHD simulations produce higher momentum yields than HD ones at equal resolution. As a result, we obtain only a lower limit on the momentum yield from clustered supernovae. Combining this with our previous 1D results, which provide an upper limit because they allow almost no mixing across the contact discontinuity, we conclude that the momentum yield per supernova from clustered supernovae in a homogeneous ISM is bounded between $2\times 10^5$ and $3\times 10^6$ $M_\odot$ km s$^{-1}$. A converged value for the simple homogeneous ISM remains elusive.
A two-dimensional collective Hamiltonian (2DCH) on both azimuth and polar motions in triaxial nuclei is proposed to investigate the chiral and wobbling modes. In the 2DCH, the collective potential and the mass parameters are determined from three-dimensional tilted axis cranking (TAC) calculations. The broken chiral and signature symmetries in the TAC solutions are restored by the 2DCH. The validity of the 2DCH is illustrated with a triaxial rotor ($\gamma=-30^\circ$) coupling to one $h_{11/2}$ proton particle and one $h_{11/2}$ neutron hole. By diagonalizing the 2DCH, the angular momenta and energy spectra are obtained. These results agree with the exact solutions of the particle rotor model (PRM) at high rotational frequencies. However, at low frequencies, the energies given by the 2DCH are larger than those by the PRM due to the underestimation of the mass parameters. In addition, with increasing angular momentum, the transitions from the chiral vibration to chiral rotation and further to longitudinal wobbling motion have been presented in the 2DCH.
We obtain asymptotic expansions for the large deviation principle (LDP) for continuous time stochastic processes with weakly dependent increments. As a key example, we show that additive functionals of solutions of stochastic differential equations (SDEs) satisfying H\"ormander condition on a $d-$dimensional compact manifold admit these asymptotic expansions of all orders.
This note concerns the problem of minimizing a certain family of non-local energy functionals over measures on $\mathbb{R}^n$, subject to a mass constraint, in a strong attraction limit. In these problems, the total energy is an integral over pair interactions of attractive-repulsive type. The interaction kernel is a sum of competing power law potentials with attractive powers $\alpha \in (0, \infty)$ and repulsive powers associated with Riesz potentials. The strong attraction limit $\alpha \to \infty$ is addressed via Gamma-convergence, and minimizers of the limit are characterized in terms of an isodiametric capacity problem. We also provide evidence for symmetry-breaking in high dimensions.
Collective charge density excitation spectra of both a spatially separated two-component quasi-one dimensional (1D) quantum plasma, as existing in a semiconductor double quantum wire structure, and a 1D homogeneous electron-hole plasma, as appropriate for a photoexcited semiconductor quantum wire system, are calculated within the two-component random-phase-approximation. We also investigate the effect of impurity scattering on the collective mode dispersion and damping, and calculate the collective mode spectral weight by obtaining the dynamical structure factor. We find that both OP and AP modes are overdamped by impurity scattering below some critical wave vector. We find that in the long wavelength limit the spectral weight is carried mostly by the OP, but the spectral weight of the undamped AP mode at finite (but not too large) wave vectors is comparable with that of the OP mode, making it viable to observe the AP mode in semiconductor quantum wire systems. The effect of the interwire electron tunneling in a biwire system on the collective charge density excitation spectra is also studied. We discuss the mode dispersion and damping from an effective Luttinger liquid perspective as well and in some cases include local field corrections in our calculations.
We present a generic algorithm to search for dwarf galaxies in photometric catalogs and apply it to the Pan-Andromeda Archaeological Survey (PAndAS). The algorithm is developed in a Bayesian framework and, contrary to most dwarf-galaxy-search codes, makes use of both the spatial and color-magnitude information of sources in a probabilistic approach. Accounting for the significant contamination from the Milky Way foreground and from the structured stellar halo of the Andromeda galaxy, we recover all known dwarf galaxies in the PAndAS footprint with high significance, even for the least luminous ones. Some Andromeda globular clusters are also recovered and, in one case, discovered. We publish a list of the 143 most significant detections yielded by the algorithm. The combined properties of the 39 most significant isolated detections show hints that at least some of these trace genuine dwarf galaxies, too faint to be individually detected. Follow-up observations by the community are mandatory to establish which are real members of the Andromeda satellite system. The search technique presented here will be used in an upcoming contribution to determine the PAndAS completeness limits for dwarf galaxies. Although here tuned to the search of dwarf galaxies in the PAndAS data, the algorithm can easily be adapted to the search for any localised overdensity whose properties can be modeled reliably in the parameter space of any catalog.
We show that the Extended Bargmann and Newton-Hooke algebras in 2+1 dimensions can be obtained as expansions of the Nappi-Witten algebra. The result can be generalized to obtain two infinite families of non-relativistic symmetries, which include the Maxwellian Exotic Bargmann symmetry, its generalized Newton-Hooke counterpart, and its Hietarinta dual. In each case, the invariant bilinear form on the Nappi-Witten algebra leads to the invariant tensor on the expanded algebra, allowing one to construct the corresponding Chern-Simons gravity theory.
Thermodynamic uncertainty relations (TURs) express a fundamental tradeoff between the precision (inverse scaled variance) of any thermodynamic current by functionals of the average entropy production. Relying on purely variational arguments, we significantly extend these inequalities by incorporating and analyzing the impact of higher statistical cumulants of entropy production within a general framework of time-symmetrically controlled computation. This allows us to derive an exact expression for the current that achieves the minimum scaled variance, for which the TUR bound tightens to an equality that we name Thermodynamic Uncertainty Theorem (TUT). Importantly, both the minimum scaled variance current and the TUT are functionals of the stochastic entropy production, thus retaining the impact of its higher moments. In particular, our results show that, beyond the average, the entropy production distribution's higher moments have a significant effect on any current's precision. This is made explicit via a thorough numerical analysis of swap and reset computations that quantitatively compares the TUT against previous generalized TURs. Our results demonstrate how to interpolate between previously-established bounds and how to identify the most relevant TUR bounds in different nonequilibrium regimes.
We show that the rigidly rotating quantum thermal distribution on flat space-time suffers from a global pathology which can be cured by introducing a cylindrical mirror if and only if it has a radius smaller than that of the speed-of-light cylinder. When this condition is met, we demonstrate numerically that the renormalized expectation value of the energy-momentum stress tensor corresponds to a rigidly rotating thermal bath up to a finite correction except on the mirror where there are the usual Casimir divergences.
For the search for scalar leptons in the Minimal Supersymmetric Standard Model (MSSM) as well as for future precision analyses of these particles an accurate knowledge of their production and decay properties is mandatory. We evaluate the cross sections for the slepton production at e+e- colliders in the MSSM with complex parameters (cMSSM). The evaluation is based on a full one-loop calculation of the production mechanisms e+e- -> slepton_s slepton_s' including soft and hard photon radiation. The dependence of the slepton production cross sections on the relevant cMSSM parameters is analyzed numerically. We find sizable contributions to many production cross sections. They amount to roughly 15% of the tree-level results but can go up to 40% or higher in extreme cases. Also the complex phase dependence of the one-loop corrections for charged slepton production was found non-negligible. The full one-loop contributions are thus crucial for physics analyses at a future linear e+e- collider such as the ILC or CLIC.
We give an account of the current state of the approch to quantum field theory via Hopf algebras and Hochschild cohomology. We emphasize the versatility and mathematical foundation of this algebraic structure, and collect algebraic structures here in one place which are either scattered over the literature, or only implicit in previous writings. In particular we point out mathematical structures which can be helpful to farther develop our mathematical understanding of quantum fields.
We present an algorithm to optimally process uniformly sampled array image data obtained with a nondestructive readout. The algorithm discards full wells, removes cosmic ray (particle) hits and other glitches, and makes a nearly optimum estimate of the signal on each pixel. The algorithm also compresses the data. The computer requirements are modest, and the results are robust. The results are shown and compared to results of Fowler sampled and processed data. Non-ideal detector performance may require some additional code, but this is not expected to cost much processing time. Known types of detector faults are addressed.
In this note we investigate the behavior at the central point of the symmetric square $L$-functions, the most frequently used $\rm{GL}(3)$ $L$-functions. We establish an asymptotic formula with arbitrary power saving for the first moment of $L(\frac{1}{2},{\rm{sym}}^2f)$ for $f\in\mathcal{H}_k$ as even $k\rightarrow\infty$, where $\mathcal{H}_k$ is an orthogonal basis of weight-$k$ Hecke eigencuspforms for $SL(2,\mathbb{Z})$. The approach taken in this note allows us to extract two secondary main terms from the error term $O(k^{-\frac{1}{2}})$ in previous studies. More interestingly, our result exhibits a connection between the symmetric square $L$-functions and quadratic fields, which is the main theme of Zagier's work "Modular forms whose coefficients involve zeta-functions of quadratic fields" in 1977. Specifically, the secondary main terms in our asymptotic formula involve central values of Dirichlet $L$-functions of characters $\chi_{-4}$ and $\chi_{-3}$ and depend on the values of $k\,({\rm{mod}}\ 4)$ and $k\,({\rm{mod}}\ 6)$, respectively.
The cataclysmic variable V893 Sco is an eclipsing dwarf nova which, apart from outbursts with comparatively low amplitudes, exhibits a particularly strong variability during quiescence on timescales of days to seconds.The present study aims to update the outdated orbital ephemerides published previously, to investigate deviations from linear ephemerides, and to characterize non-random brightness variations in a range of timescales. Light curves of V893 Sco were observed on 39 nights, spanning a total time base of about 14 years. They contain 114 eclipses which were used to significantly improve the precision of the orbital period and to study long-term variations of the time of revolution. Oscillations and similar brightness variations were studied with Fourier techniques in the individual light curves. The orbital period exhibits long-term variations with a cycle time of 10.2 years. They can be interpreted as a light travel time effect caused by the presence of a giant planet with approximately 9.5 Jupiter masses in a 4.5 AU orbit around V893 Sco. On some nights transient semi-periodic variations on timescales of several minutes can be seen which may be identified as quasi-periodic oscillations. However, it is difficult to distinguish whether they are caused by real physical mechanisms or if they are the effect of an accidental superposition of unrelated flickering flares. Simulations to investigate this question are presented.
Cosmic-ray (CR) induced heating of whole interstellar grains is an important desorption mechanism for grain surface molecules in interstellar molecular clouds. This study aims to provide a detailed temperature spectra for such CR-induced heating. For this, olivine grains with radius of 0.05, 0.1 and 0.2 microns shielded by interstellar gas with isotropic column densities characteristic to dark cores were considered. The accumulation of an ice mantle of increasing thickness was taken into account. The CR energy spectra was obtained for these column densities for 32 cosmic-ray constituents. We calculated the frequencies with which a CR nucleus with a known energy hits a grain, depositing a certain amount of energy. As a result, we obtain the energy and temperature spectra for grains affected by CR hits. This allows to improve the existing approaches on CR-induced whole-grain heating in astrochemical modeling.
In this paper we re-examine historical references to the supernova event of 1054 AD with a view to establishing a sequence astronomical events which minimizes apparent conflicts between the various sources. We find that the explosion of the supernova is likely to have occurred weeks to months before the commonly accepted date of July 4th 1054. This view is strongly supported by a number of European references to events visible in the evening sky during the spring which are likely to be associated with the appearance of the supernova. We find the best fit to the light curve based on Chinese observations and a maximum visible apparent magnitude for a supernova located at the distance to the Crab Nebula also confirms the earlier explosion date.
Thermodynamical arguments are known to be useful in the construction of physically motivated Lyapunov functionals for nonlinear stability analysis of spatially homogeneous equilibrium steady states in thermodynamically isolated systems. Unfortunately, the limitation to thermodynamically isolated systems is essential, and standard arguments are not applicable even for some very simple thermodynamically open systems.   On the other hand, the nonlinear stability of thermodynamically open systems is usually investigated using the so-called energy method. Unfortunately, the designation "energy method" is clearly a misnomer. The mathematical quantity that is traditionally referred to as the "energy" is by no means linked to the energy in the physical sense of the word. Consequently, it would seem that genuine thermodynamical concepts are of no use in the nonlinear stability analysis of thermodynamically open systems.   We show that this is not true. In particular, we propose a construction that in the case of simple heat conduction problem leads to a physically well-motivated Lyapunov functional, which effectively replaces the artificial Lyapunov functional used in the standard energy method. The proposed construction seems to be general enough to be applied in complex thermomechanical settings.
We introduce an algebra of Schouten-commuting holomorphic polyvector fields on the moduli space of stable G-bundles over a curve by using invariant forms on the Lie algebra. The generators begin in degree three -- we prove a vanishing theorem for degree two in the case of G=GL(n).
We present a multi-wavelength observational study of IRAS 17008-4040 and IRAS 17009-4042 to probe the star-formation (SF) mechanisms operational in both the sites. Each IRAS site is embedded within a massive ATLASGAL 870 micron clump (~2430 - 2900 M_sun), and several parsec-scale filaments at 160 micron are radially directed toward these clumps (at T_d ~ 25 - 32 K). The analysis of the Spitzer and VVV photometric data depicts a group of infrared-excess sources toward both the clumps, suggesting the ongoing SF activities. In each IRAS site, high-resolution GMRT radio maps at 0.61 and 1.28 GHz confirm the presence of H II regions, which are powered by B-type stars. In the site IRAS 17008-4040, a previously known O-star candidate without an H II region is identified as an infrared counterpart of the 6.7 GHz methanol maser emission (i.e. IRcmme). Based on the VLT/NACO adaptive-optics L' image (resolution ~ 0.1 arcsec), the source IRcmme is resolved into two objects (i.e. IRcmme1 and IRcmme2) within a scale of 900 AU that are found to be associated with the ALMA core G345.50M. IRcmme1 is characterized as the main accreting HMPO candidate before the onset of an ultracompact H II region. In the site IRAS 17009-4042, the 1.28 GHz map has resolved two radio sources that were previously reported as a single radio peak. Altogether, in each IRAS site, the junction of the filaments (i.e. massive clump) is investigated with the cluster of infrared-excess sources and the ongoing massive SF. These evidences are consistent with the "hub-filament" systems as proposed by Myers (2009).
Constitutive equations are derived for the viscoelastic behavior of particle-reinforced rubbers at isothermal loading with finite strains. A filled rubber is thought of as a composite medium where inclusions with high and low concentrations of junctions between chains are randomly distributed in a host matrix. The inclusions with high concentration of junctions are associated with regions of suppressed mobility of chains that surround isolated clusters of filler and its secondary network. The regions with low concentration of junctions arise during the mixing process due to the inhomogeneity in spatial distribution of a cross-linker. The viscoelastic response of elastomers is ascribed to the thermally activated processes of breakage and reformation of strands in the domains with low concentration of junctions. Stress-strain relations for particle-reinforced rubbers are developed by using the laws of thermodynamics. Adjustable parameters in the constitutive equations are found by fitting experimental data in tensile relaxation tests for several grades of unfilled and carbon black (CB) filled rubber. It is demonstrated that the relaxation rate is noticeably affected by strains. Unlike glassy polymers, where the growth of longitudinal strain results in an increase in the rate of relaxation, the growth of the elongation ratio for natural rubber (unfilled or CB reinforced) implies a decrease in the relaxation rate, which may be explained by partial crystallization of chains in the regions with low concentration of junctions.
We study multi-dimensional normal approximations on the Poisson space by means of Malliavin calculus, Stein's method and probabilistic interpolations. Our results yield new multi-dimensional central limit theorems for multiple integrals with respect to Poisson measures -- thus significantly extending previous works by Peccati, Sol\'e, Taqqu and Utzet. Several explicit examples (including in particular vectors of linear and non-linear functionals of Ornstein-Uhlenbeck L\'evy processes) are discussed in detail.