ShantanuT01/DACTYL-Pretraining huggingface dataset:
Over the last ~5 years we have identified ~35 black hole candidates (BHCs) in M31 from their X-ray spectra. Our BHCs exhibited 0.3--10 keV spectra consistent with the X-ray binary (XB) hard state, at luminosities that are above the upper limit for neutron star (NS) XBs. When our BHC spectra were modeled with a disk blackbody + blackbody model, for comparison with bright NS XBs, we found that the BHCs inhabited a different parameter space to the NS XBs. However, BH XBs may also exhibit a thermally dominated (TD) state that has never been seen in NS XBs; this TD state is most often observed in X-ray transients. We examined the ~50 X-ray transients in our Chandra survey of M31, and found 13 with spectra suitable for analysis. We also examined 2 BHCs outside the field of view of our survey, in the globular clusters B045 and B375. We have 42 strong BHCs, and 8 plausible BHCs that may benefit from further observation. Of our 15 BHCs in globular clusters, 12 differ from NS spectra by >5 sigma. Due to improvements in our analysis, we have upgraded 10 previously identified plausible BHCs to strong BHCs. The mean maximum duty cycle of the 33 X-ray transients within 6' of M31* was 0.13; we estimate that >40% of the XBs in this region contain BH accretors. Remarkably, we estimate that BHCs contribute >90% of those XBs >1 E+38 erg/s.
Synchrotron-emitting, nonthermal filaments (NTFs) have been observed near the Galactic center for nearly four decades, yet their physical origin remains unclear. Here we investigate the possibility that NTFs are produced by the destruction of molecular clouds by the gravitational potential of the Galactic center. We show that this model predicts the formation of a filamentary structure with length on the order of tens to hundreds of pc, a highly ordered magnetic field along the axis of the filament, and conditions conducive to magnetic reconnection that result in particle acceleration. This model therefore yields the observed magnetic properties of NTFs and a population of relativistic electrons, without the need to appeal to a dipolar, $\sim$ mG, Galactic magnetic field. As the clouds can be both completely or partially disrupted, this model provides a means of establishing the connection between filamentary structures and molecular clouds that is observed in some, but not all, cases.
Self-supervised depth estimation has shown its great effectiveness in producing high quality depth maps given only image sequences as input. However, its performance usually drops when estimating on border areas or objects with thin structures due to the limited depth representation ability. In this paper, we address this problem by proposing a semantic-guided depth representation enhancement method, which promotes both local and global depth feature representations by leveraging rich contextual information. In stead of a single depth network as used in conventional paradigms, we propose an extra semantic segmentation branch to offer extra contextual features for depth estimation. Based on this framework, we enhance the local feature representation by sampling and feeding the point-based features that locate on the semantic edges to an individual Semantic-guided Edge Enhancement module (SEEM), which is specifically designed for promoting depth estimation on the challenging semantic borders. Then, we improve the global feature representation by proposing a semantic-guided multi-level attention mechanism, which enhances the semantic and depth features by exploring pixel-wise correlations in the multi-level depth decoding scheme. Extensive experiments validate the distinct superiority of our method in capturing highly accurate depth on the challenging image areas such as semantic category borders and thin objects. Both quantitative and qualitative experiments on KITTI show that our method outperforms the state-of-the-art methods.
Suppose that red and blue points occur as independent Poisson processes of equal intensity in R^d, and that the red points are matched to the blue points via straight edges in a translation-invariant way. We address several closely related properties of such matchings. We prove that there exist matchings that locally minimize total edge length in d=1 and d>=3, but not in the strip R x [0,1]. We prove that there exist matchings in which every bounded set intersects only finitely many edges in d>=2, but not in d=1 or in the strip. It is unknown whether there exists a matching with no crossings in d=2, but we prove positive answers to various relaxations of this question. Several open problems are presented.
We explore the possibility of replacing point set topology by higher category theory and topos theory as the foundation for quantum general relativity. We discuss the BC model and problems of its interpretation, and connect with the construction of causal sites.
We study the Cosmic Microwave Background (CMB) anisotropies produced by cosine-type quintessence models. In our analysis, effects of the adiabatic and isocurvature fluctuations are both taken into account. For purely adiabatic fluctuations with scale invariant spectrum, we obtain a stringent constraint on the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA. Furthermore, it is shown that isocurvature fluctuations have significant effects on the CMB angular power spectrum at low multipoles in some parameter space, which may be detectable in future satellite experiments. Such a signal may be used to test the cosine-type quintessence models.
A variation of multiple $L$-values, which arises from the description of the special values of the spectral zeta function of the non-commutative harmonic oscillator, is introduced. In some special cases, we show that its generating function can be written in terms of the gamma functions. This result enables us to obtain explicit evaluations of them.
In this article, we consider the quasi-linear stochastic wave and heat equations on the real line and with an additive Gaussian noise which is white in time and behaves in space like a fractional Brownian motion with Hurst index $H\in (0,1)$. The drift term is assumed to be globally Lipschitz. We prove that the solution of each of the above equations is continuous in terms of the index $H$, with respect to the convergence in law in the space of continuous functions.
A new mechanism for the pp --> pp pi0 reaction close to threshold is suggested coming from the isoscalar excitation of the Roper and its decay into N(pi pi)S-wave, with one of the pi0 emitted and the other one reabsorbed on the second nucleon. The mechanism can lead to important interference with other mechanisms and, together with experiment, serves to exclude large ranges of the 2pi N* decay parameters allowed by the N* partial decay widths.
We present a detailed analysis of ALMA Bands 7 and 9 data of CO, HCO+, HCN and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the ~ 200 pc circumnuclear disk (CND) and the ~ 1.3 kpc starburst ring (SB ring) of NGC~1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim at determining the physical characteristics of the dense gas present in the CND and whether the different line intensity ratios we find within the CND as well as between the CND and the SB ring are due to excitation effects (gas density and temperature differences) or to a different chemistry. We estimate the column densities of each species in Local Thermodynamic Equilibrium (LTE). We then compute large one-dimensional non-LTE radiative transfer grids (using RADEX) by using first only the CO transitions, and then all the available molecules in order to constrain the densities, temperatures and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas. We find that in general the gas in the CND is very dense (> 10^5 cm^-3) and hot (T> 150K), with differences especially in the temperature across the CND. The AGN position has the lowest CO/HCO+, CO/HCN and CO/CS column density ratios. RADEX analyses seem to indicate that there is chemical differentiation across the CND. We also find differences between the chemistry of the SB ring and some regions of the CND; the SB ring is also much colder and less dense than the CND. Chemical modelling does not succeed in reproducing all the molecular ratios with one model per region, suggesting the presence of multi-gas phase components. The LTE, RADEX and chemical analyses all indicate that more than one gas-phase component is necessary to uniquely fit all the available molecular ratios within the CND.
The simplest solution to the black hole information loss problem is to eliminate black holes. Modifications of Einstein gravity which accomplish this are discussed and the possibility that string theory is free of black holes is considered.
Nonanalytic $m_q^{1/2}$ and $m_q\ln m_q$ chiral corrections to the baryon magnetic moments are computed. The calculation includes contributions from both intermediate octet and decuplet baryon states. Unlike the one-loop contributions to the baryon axial currents and masses, the contribution from decuplet intermediate states does not partially cancel that from octet intermediate states. The fit to the observed magnetic moments including $m_q^{1/2}$ corrections is found to be much worse than the tree level SU(3) fit if values for the baryon-pion axial coupling constants obtained from a tree level extraction are used. Using the axial coupling constant values extracted at one loop results in a better fit to the magnetic moments than the tree level SU(3) fit. There are three linear relations amongst the magnetic moments when $m_q^{1/2}$ corrections are included, and one relation including $m_q^{1/2}$, $m_q\ln m_q$ and $m_q$ corrections. These relations are independent of the axial coupling constants of the baryons and agree well with experiment.
We revisit the dynamics of the one-dimensional self-gravitating sheets models. We show that homogeneous and non-homogeneous states have different ergodic properties. The former is non-ergodic and the one-particle distribution function has a zero collision term if a proper limit is taken for the periodic boundary conditions. Non-homogeneous states are ergodic in a time window of the order of the relaxation time to equilibrium, as similarly observe in other systems with a long range interaction. For the sheets model this relaxation time is much larger than other systems with long range interactions if compared to the initial violent relaxation time.
Treating the Teukolsky perturbation equation numerically as a 2+1 PDE and smearing the singularities in the particle source term by the use of narrow Gaussian distributions, we have been able to reproduce earlier results for equatorial circular orbits that were computed using the frequency domain formalism. A time domain prescription for a more general evolution of nearly geodesic orbits under the effects of radiation reaction is presented. This approach can be useful when tackling the more realistic problem of a stellar-mass black hole moving on a generic orbit around a supermassive black hole under the influence of radiation reaction forces.
We propose a single-site addressing implementation based on the sub-wavelength localization via adiabatic passage (SLAP) technique. We consider a sample of ultracold neutral atoms loaded into a two-dimensional optical lattice with one atom per site. Each atom is modeled by a three-level \Lambda-system in interaction with a pump and a Stokes laser pulse. Using a pump field with a node in its spatial profile, the atoms at all sites are transferred from one ground state of the system to the other via stimulated Raman adiabatic passage, except the one at the position of the node that remains in the initial ground state. This technique allows for the preparation, manipulation, and detection of atoms with a spatial resolution better than the diffraction limit, which either relaxes the requirements on the optical setup used or extends the achievable spatial resolution to lattice spacings smaller than accessible to date. In comparison to techniques based on coherent population trapping, SLAP gives a higher addressing resolution and has additional advantages such as robustness against parameter variations, coherence of the transfer process, and the absence of photon induced recoil. Additionally, the advantages of our proposal with respect to adiabatic spin-flip techniques are highlighted. Analytic expressions for the achievable addressing resolution and efficiency are derived and compared to numerical simulations for Rb-87 atoms in state-of-the-art optical lattices.
Large infrared and millimeter wavelength surveys of the Galactic plane have unveiled more than 600 new bubble HII regions and more than 3000 candidate star clusters. We present a study of the candidate clusters MCM2005b72, DBS2003-157, DBS2003-172, and MCM2005b77, based on near-infrared spectroscopy taken with SofI on the NTT and infrared photometry from the 2MASS, VVV, and GLIMPSE surveys. We find that (1) MCM2005b72 and DBS2003-157 are subregions of the same star-forming region, HII GRS G331.34-00.36 (bubble S62). MCM2005b72 coincides with the central part of this HII region, while DBS2003-157 is a bright mid-infrared knot of the S62 shell. We detected two O-type stars at extinction \Aks=1.0-1.3 mag. Their spectrophotometric properties are consistent with the near-kinematic distance to GRS G331.34-00.36 of 3.9pm0.3 kpc. (2) DBS2003-172 coincides with a bright mid-infrared knot in the S36 shell (GRS G337.92-00.48), where we detected a pair of candidate He I stars embedded in a small cometary nebula. (3) The stellar cluster MCM2005b77 is rich in B-type stars, has an average Aks of 0.91 mag, and is adjacent to the HII region IRAS 16137-5025. The average spectrophotometric distance of $\sim 5.0$ kpc matches the near-kinematic distance to IRAS 16137-5025 of 5.2pm0.1 kpc.
Within the scope of a spherically symmetric space-time we study the role of a nonlinear spinor field in the formation of different configurations with spherical symmetries. The presence of the non-diagonal components of energy-momentum tensor of the spinor field leads to some severe restrictions on the spinor field itself. Since spinor field is the source of the gravitational one, the metric functions also changes in accordance with it. The system as a whole possesses solutions only in case of some additional conditions on metric functions.
Recently, some reformulations of the Yang-Mills theory inspired by the Cho-Faddeev-Niemi decomposition have been developed in order to understand confinement from the viewpoint of the dual superconductivity. In this paper we focus on the reformulated $SU(N)$ Yang-Mills theory in the minimal option with $U(N-1)$ stability group. Despite existing numerical simulations on the lattice we perform the perturbative analysis to one-loop level as a first step towards the non-perturbative analytical treatment. First, we give the Feynman rules and calculate all renormalization factors to obtain the standard renormalization group functions to one-loop level in light of the renormalizability of this theory. Then we introduce a mixed gluon ghost composite operator of mass dimension two and show the BRST invariance and the multiplicative renormalizability. Armed with these results, we argue the existence of the mixed gluon-ghost condensate by means of the so-called local composite operator formalism, which leads to various interesting implications for confinement as shown in preceding works.
We aim at finding a cosmologically motivated infall law to understand if the LambdaCDM cosmology can reproduce the main chemical characteristics of a Milky Way-like spiral galaxy. In this work we test several different gas infall laws, starting from that suggested in the two-infall model for the chemical evolution of the Milky Way by Chiappini et al., but focusing on laws derived from cosmological simulations which follows a concordance LambdaCDM cosmology. By means of a detailed chemical evolution model for the solar vicinity, we study the effects of the different gas infall laws on the abundance patterns and the G-dwarf metallicity distribution. The cosmological gas infall law predicts two main gas accretion episodes. By means of this cosmologically motivated infall law, we study the star formation rate, the SNIa and SNII rate, the total amount of gas and stars in the solar neighbourhood and the behaviour of several chemical abundances. We find that the results of the two-infall model are fully compatible with the evolution of the Milky Way with cosmological accretion laws. A gas assembly history derived from a DM halo, compatible with the formation of a late-type galaxy from the morphological point of view, can produce chemical properties in agreement with the available observations.
The 1-loop effective potential in a scalar theory with quartic interaction on the space $M^{4} \times T^{n}$ for $n=2$ is calculated and is shown to be unbounded from below. This is an indication of a possible instability of the vacuum of the $\lambda \phi^{4}$ theory on $M^{4}$, when it is regarded as a result of the dimensional reduction of the original six-dimensional model. The issue of stability for other values of the number $n$ of extra dimensions is also discussed.
During its first cycle of observations, VERITAS observed several GRBs in response to broadcast alerts from the Gamma-ray bursts Coordinates Network (GCN). The GRBs were followed up and observed thereafter with typical delays of 2 to 4 minutes from the beginning of the burst and of 92 s in the best case, searching for a very high energy (VHE) component above 100 GeV. The aim of the search for VHE emission from GRBs is to understand the behavior, composition and dynamics of the most accelerated particles in the bursts, as well as to get a better overall understanding of the model of GRBs. We report on the results from two years of observations by VERITAS.
We compute the spectrum and Smith normal form of the incidence matrix of disjoint transversals, a combinatorial object closely related to the n-dimensional case of Rota's basis conjecture.
In this manuscript, the modification of thermodynamic properties of Schwarzschild and Reissner-Nordstr\"{o}m black holes in the presence of higher-order generalized uncertainty principle (GUP) have been investigated. We considered heuristic analysis versus the behavior of a particle that is absorbed by the black hole, and then, we studied the thermodynamic properties of the black holes such as temperature-mass, temperature-charge-mass, entropy, and heat capacity functions up to the first and second-order of the GUP parameter. We compared the behaviors of the GUP-corrected thermodynamic properties for both black holes with graphical methods.
In this letter, a very simple no-reference image quality assessment (NR-IQA) model for JPEG compressed images is proposed. The proposed metric called median of unique gradients (MUG) is based on the very simple facts of unique gradient magnitudes of JPEG compressed images. MUG is a parameterless metric and does not need training. Unlike other NR-IQAs, MUG is independent to block size and cropping. A more stable index called MUG+ is also introduced. The experimental results on six benchmark datasets of natural images and a benchmark dataset of synthetic images show that MUG is comparable to the state-of-the-art indices in literature. In addition, its performance remains unchanged for the case of the cropped images in which block boundaries are not known. The MATLAB source code of the proposed metrics is available at https://dl.dropboxusercontent.com/u/74505502/MUG.m and https://dl.dropboxusercontent.com/u/74505502/MUGplus.m.
Excited baryons may be analyzed in the 1/N_c expansion as true resonances in scattering amplitudes. The key idea making this program possible is a generalization of methods originally applied to chiral soliton models in the 1980's. One finds model-independent relations among amplitudes that impose mass and width degeneracies among resonances of various quantum numbers. Phenomenological evidence demonstrates that patterns of resonant decay predicted by 1/N_c agree with data. The analysis can be extended to subleading orders in 1/N_c, where again agreement with data is evident.
Strain and rotation fields of dislocations in monolayer graphene have been mapped in a recent experiment. These fields are finite everywhere and differ from those given by linear elasticity which does not consider rotation explicitly and predicts infinite rotation and strains at the dislocation point. A derivative regularization of two-dimensional linear elasticity fixes these shortcomings. The theory adds rotation, dislocation and residual strain energies to the usual elastic energy. There are two extra material constants that determine the size of the dislocation core and are determined from experimental data. These findings are useful for studies of dislocations in graphene and for analyzing incipient plasticity in two dimensional crystals.
The surprisingly low current density required for inducing the insulator to metal transition has made Ca$_2$RuO$_4$ an attractive candidate material for developing Mott-based electronics devices. The mechanism driving the resistive switching, however, remains a controversial topic in the field of strongly correlated electron systems. Here we probe an uncovered region of phase space by studying high-purity Ca$_2$RuO$_4$ single crystals, using the sample size as principal tuning parameter. Upon reducing the crystal size, we find a four orders of magnitude increase in the current density required for driving Ca$_2$RuO$_4$ out of the insulating state into a non-equilibrium (also called metastable) phase which is the precursor to the fully metallic phase. By integrating a microscopic platinum thermometer and performing thermal simulations, we gain insight into the local temperature during simultaneous application of current and establish that the size dependence is not a result of Joule heating. The findings suggest an inhomogeneous current distribution in the nominally homogeneous crystal. Our study calls for a reexamination of the interplay between sample size, charge current, and temperature in driving Ca$_2$RuO$_4$ towards the Mott insulator to metal transition.
The paper deals with a sharing economy system with various management factors by using a bulk input G/M/1 type queuing model. The effective management of operating costs is vital for controlling the sharing economy platform and this research builds the theoretical background to understand the sharing economy business model. Analytically, the techniques include a classical Markov process of the single channel queueing system, semi-Markov process and semi-regenerative process. It uses the stochastic congruent properties to find the probability distribution of the number of contractors in the sharing economy platform. The obtained explicit formulas demonstrate the usage of functional for the main stochastic characteristics including sharing expenses due to over contracted resources and optimization of their objective function.
We present a new exponential inequality as a generalization of that of Sung \textit{et al.} \cite{sun2011} for $M$-acceptable random variables, and hence for extended negative ones. Our result is based on the simple real inequality $e^{x} \leq 1+x+(|x|/2)e^{|x|}, x\in\mathbb{R}$, in place of the following one: $e^{x} \leq 1+x+(x^{2}/2)e^{|x|}, x\in\mathbb{R}$, used by many authors. We compare the given bound with former ones.
Let $X \to S$ be a miniversal family of smooth and projective varieties and D be a fixed triangulated category. We show that the set of points s in S such that the derived category of the fiber X_s at s is equivalent to D is at most countable. We deduce from this that the derived equivalence classes of smooth and projective complex varieties is at most countable.