ShantanuT01/DACTYL-Pretraining huggingface dataset:
We present the mass-metallicity (MZ) and luminosity-metallicity (LZ) relations at z ~ 0.8 from ~1350 galaxies in the Deep Extragalactic Evolutionary Probe 2 (DEEP2) survey. We determine stellar masses by fitting the spectral energy distribution inferred from photometry with current stellar population synthesis models. This work raises the number of galaxies with metallicities at z ~ 0.8 by more than an order of magnitude. We investigate the evolution in the MZ and LZ relations in comparison with local MZ and LZ relations determined in a consistent manner using ~21,000 galaxies in the Sloan Digital Sky Survey. We show that high stellar mass galaxies (log(M/M_solar)~10.6) at z ~ 0.8 have attained the chemical enrichment seen in the local universe, while lower stellar mass galaxies (log(M/M_solar)~9.2) at z ~ 0.8 have lower metallicities (Delta log(O/H)~0.15 dex) than galaxies at the same stellar mass in the local universe. We find that the LZ relation evolves in both metallicity and B-band luminosity between z ~ 0.8 and z~ 0, with the B-band luminosity evolving as a function of stellar mass. We emphasize that the B-band luminosity should not be used as a proxy for stellar mass in chemical evolution studies of star-forming galaxies. Our study shows that both the metallicity evolution and the B-band luminosity evolution for emission-line galaxies between the epochs are a function of stellar mass, consistent with the cosmic downsizing scenario of galaxy evolution.
We prove the existence and uniqueness of an equilibrium state with unit mass to the dissipative linear Boltzmann equation with hard--spheres collision kernel describing inelastic interactions of a gas particles with a fixed background. The equilibrium state is a universal Maxwellian distribution function with the same velocity as field particles and with a non--zero temperature lower than the background one, which depends on the details of the binary collision. Thanks to the H--theorem we then prove strong convergence of the solution to the Boltzmann equation towards the equilibrium.
We study Brauer-Manin obstructions to the Hasse principle and to weak approximation with special regard to effectivity questions.
For positive integers $d<k$ and $n$ divisible by $k$, let $m_{d}(k,n)$ be the minimum $d$-degree ensuring the existence of a perfect matching in a $k$-uniform hypergraph. In the graph case (where $k=2$), a classical theorem of Dirac says that $m_{1}(2,n)=\lceil n/2\rceil$. However, in general, our understanding of the values of $m_{d}(k,n)$ is still very limited, and it is an active topic of research to determine or approximate these values. In this paper we prove a "transference" theorem for Dirac-type results relative to random hypergraphs. Specifically, for any $d< k$, any $\varepsilon>0$ and any "not too small" $p$, we prove that a random $k$-uniform hypergraph $G$ with $n$ vertices and edge probability $p$ typically has the property that every spanning subgraph of $G$ with minimum degree at least $(1+\varepsilon)m_{d}(k,n)p$ has a perfect matching. One interesting aspect of our proof is a "non-constructive" application of the absorbing method, which allows us to prove a bound in terms of $m_{d}(k,n)$ without actually knowing its value.
In this work stochastic integration with respect to cylindrical Levy processes with weak second moments is introduced. It is well known that a deterministic Hilbert-Schmidt operator radonifies a cylindrical random variable, i.e. it maps a cylindrical random variable to a classical Hilbert space valued random variable. Our approach is based on a generalisation of this result to the radonification of the cylindrical increments of a cylindrical Levy process by random Hilbert-Schmidt operators. This generalisation enables us to introduce a Hilbert space valued random variable as the stochastic integral of a predictable stochastic process with respect to a cylindrical Levy process. We finish this work by deriving an Ito isometry and by considering shortly stochastic partial differential equations driven by cylindrical Levy processes.
In this paper, we prove the existence of classical solutions to second boundary value prob- lems for generated prescribed Jacobian equations, as recently developed by the second author, thereby obtaining extensions of classical solvability of optimal transportation problems to problems arising in near field geometric optics. Our results depend in particular on a priori second derivative estimates recently established by the authors under weak co-dimension one convexity hypotheses on the associated matrix functions with respect to the gradient variables, (A3w). We also avoid domain deformations by using the convexity theory of generating functions to construct unique initial solutions for our homotopy family, thereby enabling application of the degree theory for nonlinear oblique boundary value problems.
We studied the field dependent thermal conductivity ($\kappa$) of Na$_2$Co$_2$TeO$_6$, a compound considered as the manifestation of the Kitaev model based on the high-spin $d^7$ Co$^{2+}$ ions. We found that in-plane magnetic fields beyond a critical value $B_c \approx$~10 T are able to drastically enhance $\kappa$ at low temperatures, resulting in a double-peak structure of $\kappa(T)$ that closely resembles the behavior of $\alpha$-RuCl$_3$. This result suggests that heat transport in Na$_2$Co$_2$TeO$_6$ is primarily phononic, and it is strongly affected by scattering from magnetic excitations that are highly tunable by external fields. Interestingly, for magnetic fields $B // a$ (i.e., along the zigzag direction of the Co-Co bonds), there is an extended field range which separates the long-range magnetic order for $B\leq B_c\approx10$ T and the partially spin-polarized gapped high-field phase for $B\gtrsim 12$ T. The low-energy phonon scattering is particularly strong in this field range, consistent with the notion that the system becomes a quantum spin liquid with prominent spin fluctuations down to energies of no more than 2 meV.
In this paper, we establish a version of the large sieve with square moduli for imaginary quadratic extensions of rational function fields of odd characteristics.
We study the entanglement of a multipartite quantum state. An inequality between the bipartite concurrence and the multipartite concurrence is obtained. More effective lower and upper bounds of the multipartite concurrence are obtained. By using the lower bound, the entanglement of more multipartite states are detected.
We present some general results for the time-dependent mass Hamiltonian problem with H=-{1/2}e^{-2\nu}\partial_{xx} +h^{(2)}(t)e^{2\nu}x^2. This Hamiltonian corresponds to a time-dependent mass (TM) Schr\"odinger equation with the restriction that there are only P^2 and X^2 terms. We give the specific transformations to a different quantum Schr\"odinger(TQ) equation and to a different time-dependent oscillator (TO) equation. For each Schr\"odinger system, we give the Lie algebra of space-time symmetries and (x,t) representations for number states, coherent states, and squeezed states. These general results include earlier work as special cases.
We have developed in the previous works a statistical model of quantum fluctuation based on a chaotic deviation from infinitesimal stationary action which is constrained by the principle of Locality to have a unique exponential distribution up to a parameter that determines its average. The unitary Schr\"odinger time evolution with Born's statistical interpretation of wave function is recovered as a specific case when the average deviation from infinitesimal stationary action is given by $\hbar/2$ for all the time. This naturally suggests a possible generalization of the quantum dynamics and statistics by allowing the average deviation fluctuates effectively randomly around $\hbar/2$ with a finite yet very small width and a finite time scale. We shall show that averaging over such fluctuation will lead to a non-unitary average-energy-conserving time evolution providing an intrinsic mechanism of decoherence in energy basis in macroscopic regime. A possible cosmological origin of the fluctuation is suggested. Coherence and decoherence are thus explained as two features of the same statistical model corresponding to microscopic and macroscopic regimes, respectively. Moreover, noting that measurement-interaction can be treated in equal footing as the other types of interaction, the objective locality of the model is argued to imply no-signaling between a pair of arbitrarily separated experiments.
The growth of supermassive black holes, especially the associated state of active galactic nuclei (AGNs), is generally believed to be the key step in regulating star formation in massive galaxies. As the fuel of star formation, the cold gas reservoir is a direct probe of the effect of AGN feedback on their host galaxies. However, in observation, no clear connection has been found between AGN activity and the cold gas mass. In this paper, we find observational signals of significant depletion of the total neutral hydrogen gas reservoir in optically-selected type-2 AGN host central galaxies of stellar mass $10^{9}$--$10^{10}M_\odot$. The effect of AGN feedback on the cold gas reservoir is stronger for higher star formation rates and higher AGN luminosity. But it becomes much weaker above this mass range, consistent with previous findings focusing on massive galaxies. Our result suggests that low-mass and gas-rich AGN host central galaxies would first form dense cores before AGN feedback is triggered, removing their neutral hydrogen gas. More massive central galaxies may undergo a significantly different formation scenario by gradually building up dense cores with less effective and recurrent AGN feedback.
An iterative map of the unit disc in the complex plane (Appendix) is used to explore certain aspects of selfdual, four dimensional gauge fields (quasi)periodic in the Euclidean time. These fields are characterized by two topological numbers and contain standard instantons and monopoles as different limits. The iterations do not correspond directly to a discretized time evolution of the gauge fields. They are implemented in an indirect fashion. First, (t,r,\theta,\phi) being the standard coordinates, the (r,t) half plane is mapped on the unit disc in an appropriate way. This provides an (r,t) parametrization (Sec.1) of Z_0, the starting point of the iterations and makes the iterates increasingly complex functions of r and t. These are then incorporated as building blocks in the generating function of the fields (Sec.2). We explain (starting in Sec.1 and at different stages) in what sense and to what extent some remarkable features of our map (indicated in the title) are thus carried over into the continuous time development of the fields. Special features for quasiperiodicity are studied (Sec.3). Spinor solutions (Sec.4) and propagators (Sec.5) are discussed from the point of view of the mapping. Several possible generalizations are indicated (Sec.6). Some broader topics are discussd in conclusion (Sec.7).
We prove almost sure convergence of the maximum degree in an evolving graph model combining a growing number of local choices with sublinear preferential attachment. At each step in the growth of the graph, a new vertex is introduced. Then we draw a random number of edges from it to existing vertices, chosen independently by the following rule. For each edge, we consider a sample of the growing size of vertices chosen with probabilities proportional to the sublinear function of their degrees. Then new vertex attaches to the vertex with the highest degree from the sample. Depending on the growth rate of the sample and the sublinear function, the maximum degree could be of the sublinear order, of the linear order or having almost all edges drawing to it. The prove using various stochastic approximation processes and a large deviation approach.
We survey the application of computer algebra in the context of gravitational theories. After some general remarks, we show of how to check the second Bianchi-identity by means of the Reduce package Excalc. Subsequently we list some computer algebra systems and packages relevant to applications in gravitational physics. We conclude by presenting a couple of typical examples.
We derive a bound for the security of QKD with finite resources under one-way post-processing, based on a definition of security that is composable and has an operational meaning. While our proof relies on the assumption of collective attacks, unconditional security follows immediately for standard protocols like Bennett-Brassard 1984 and six-states. For single-qubit implementations of such protocols, we find that the secret key rate becomes positive when at least N\sim 10^5 signals are exchanged and processed. For any other discrete-variable protocol, unconditional security can be obtained using the exponential de Finetti theorem, but the additional overhead leads to very pessimistic estimates.
With the development of network and the World Wide Web (WWW), the Internet has been growing and changing dramatically. More and more on-line database systems and different kinds of services are available for astronomy research. How to help users find their way through the jungle of information services becomes an important challenge. Although astronomers have been aware of the importance of interoperability and introduced the concept of Virtual Observatory as a uniform environment for future astronomical on-line resources and services, transparent access to heterogeneous on-line information is still difficult.   SkyMouse is a lightweight interface for distributed astronomical on-line resources and services, which is designed and developed by us, i.e., Chinese Virtual Observatory Project. Taking advantage of screen word-capturing technology, different kinds of information systems can be queried through simple mouse actions, and results are returned in a uniform web page. SkyMouse is an easy to use application, aiming to show basic information or to create a comprehensive overview of a specific astronomical object.   In this paper current status of on-line resources and services access is reviewed; system architecture, features and functions of SkyMouse are described; challenges for intelligent interface for on-line astronomical resources and services are discussed.
Correlated interaction between dilute localized impurity electrons with the itinerant host conduction electrons in metals gives rise to the conventional many-body Kondo effect below sufficiently low temperature. In sharp contrast to these conventional Kondo systems, we report an intrinsic, robust and high-temperature Kondo state in two-dimensional semiconducting phosphorene. While absorbed at a thermodynamically stable lattice defect, Cr impurity triggers an electronic phase transition in phosphorene to provide conduction electrons, which strongly interact with the localized moment generated at the Cr site. These manifests into intrinsic Kondo state, where the impurity moment is quenched at multi-stage and at temperatures in the 40-200 K range. Further, along with a much smaller extension of Kondo cloud, the predicted Kondo state is shown to be robust under uniaxial strain and layer thickness, which greatly simplifies its future experimental realization. We predict the present study will open up new avenues in Kondo physics and trigger further theoretical and experimental studies.
We present a detailed analysis of the behaviour of the Red Clump K-band absolute magnitude (M(K,RC)) in simple and composite stellar populations, in light of its use as standard candle for distance determinations. The advantage of using M(K,RC), following recent empirical calibrations of its value for the solar neighbourhood, arises from its very low sensitivity to the extinction by interstellar dust. We provide data and equations which allow the determination of the K-band population correction Delta(M(K,RC)) (difference between the Red Clump brightness in the solar neighbourhood and in the population under scrutiny) for any generic stellar population. These data complement the results presented in Girardi & Salaris(2001) for the V- and I-band. We show how data from galactic open clusters consistently support our predicted Delta(M(V,RC)), Delta(M(I,RC)) and Delta(M(K,RC)) values.   Multiband VIK population corrections for various galaxy systems are provided. They can be used in conjunction with the method devised by Alves et al.(2002), in order to derive simultaneously reddening and distance from the use of VIK observations of Red Clump stars. We have positively tested this technique on the Galactic globular cluster 47Tuc, for which both an empirical parallax-based main sequence fitting distance and reddening estimates exist. We have also studied the case of using only V and I photometry, recovering consistent results for both reddening and distance. Application of this method to an OGLE-II field, and the results by Alves et al.(2002), confirm a LMC distance modulus of about 18.50, in agreement with the HST extragalactic distance scale zero-point. (abridged)
Active galactic nuclei (AGN) are believed to be the source of ultra high energy cosmic rays (UHECRs). Particles are assumed to be accelerated in the accretion disk and the plasma jets, produced due to conservation of angular momentum, to the highest energies, where they interact with each other and produce pions, which decay among others in neutrinos. For a known cosmic ray spectral behavior, the main parameters in the calcula- tion of the neutrino flux from proton-proton interactions are the target density nH and the ratio of electrons to protons fe . Using most recent neutrino flux limits from IceCube point source searches, we set limits on the target densities for 33 FR-I galaxies. The densities are shown to be smaller than 30 cm^{-3} to 2000 cm^{-3}, depending on the source and when using a fixed electron to proton ratio of f_{e} = 0.1. This implies that some cosmic ray acceleration sites, espe- cially those close to the core of the AGN, can already be excluded, or else that the ratio of electrons to protons deviates significantly from the commonly used value of 0.1. For Centaurus A (Cen A) and Messier 87 (M 87) we use Fermi observations to model the {\gamma}-flux, the neutrino flux and the resulting target density. The detec- tion of these neutrinos will help to find information about acceleration processes in the source.
This chapter reviews our current knowledge of metal-poor ultracool dwarfs with spectral types later than M7. The current census of M, L, and T subdwarfs is explored. The main colour trends of subdwarfs from the optical to the mid-infrared are described and their spectral features presented, which led to a preliminary and tentative spectral classification subject to important changes in the future when more of these metal-poor objects are discovered. Their multiplicity and the determination of their physical parameters (effective temperature, gravity, metallicity, and mass) are discussed. Finally, some suggestions and future guidelines are proposed to foster our knowledge on the oldest and coolest members of our Galaxy.
The mixed spin 3- spin 3/2 Ising model has been simulated using cooling algorithm on cellular automaton (CA). The simulations have been made in the interval -6<=D<=6 for J=1 for the square lattices with periodic boundary conditions. The ground state phase diagram of the model has different type ferrimagnetic orderings. Through D/J=2 line, compensation points occurs at kT/J=0. The values of the critical exponents ( {\nu}, {\alpha}, {\beta} and {\gamma}) are estimated within the framework of the finite-size scaling theory and power law relations for selected D/J values (-2, 0, 1, 2 and 4). The estimated critical exponent values are in a good agreement with their universal values of the two dimensional Ising model.
We analyze various prominent quantum repeater protocols in the context of long-distance quantum key distribution. These protocols are the original quantum repeater proposal by Briegel, D\"ur, Cirac and Zoller, the so-called hybrid quantum repeater using optical coherent states dispersively interacting with atomic spin qubits, and the Duan-Lukin-Cirac-Zoller-type repeater using atomic ensembles together with linear optics and, in its most recent extension, heralded qubit amplifiers. For our analysis, we investigate the most important experimental parameters of every repeater component and find their minimally required values for obtaining a nonzero secret key. Additionally, we examine in detail the impact of device imperfections on the final secret key rate and on the optimal number of rounds of distillation when the entangled states are purified right after their initial distribution.
Let $G$ be a graph with nonnegative integer weights. A {\it unit acquisition move} transfers one unit of weight from a vertex to a neighbor that has at least as much weight. The {\it unit acquisition number} of a graph $G$, denoted $a_u(G)$, is the minimum size that the set of vertices with positive weight can be reduced to via successive unit acquisition moves when starting from the configuration in which every vertex has weight $1$.   For a graph $G$ with $n$ vertices and minimum degree $k$, we prove $a_u(G)\le (n-1)/k$, with equality for complete graphs and $C_5$. Also $a_u(G)$ is at most the minimum size of a maximal matching in $G$, with equality on an infinite family of graphs. Furthermore, $a_u(G)$ is bounded by the maximum degree and by $\sqrt{n-1}$ when $G$ is an $n$-vertex tree with diameter at most $4$. We also construct arbitrarily large trees with maximum degree $5$ having unit acquisition number $1$, obtain a linear-time algorithm to compute the acquisition number of a caterpillar, and show that graphs with diameter $2$ have unit acquisition number $1$ except for $C_5$ and the Petersen graph.
The spin-$1/2$ chain with antiferromagnetic exchange $J_1$ and $J_2 = \alpha J_1$ between first and second neighbors, respectively, has both gapless and gapped ($\Delta(\alpha) > 0$) quantum phases at frustration $0 \le \alpha \le 3/4$. The ground state instability of regular ($\delta = 0$) chains to dimerization ($\delta > 0$) drives a spin-Peierls transition at $T_{SP}(\alpha)$ that varies with $\alpha$ in these strongly correlated systems. The thermodynamic limit of correlated states is obtained by exact treatment of short chains followed by density matrix renormalization calculations of progressively longer chains. The doubly degenerate ground states of the gapped regular phase are bond order waves (BOWs) with long-range bond-bond correlations and electronic dimerization $\delta_e(\alpha)$. The $T$ dependence of $\delta_e(T,\alpha)$ is found using four-spin correlation functions and contrasted to structural dimerization $\delta(T,\alpha)$ at $T \le T_{SP}(\alpha)$. The relation between $T_{SP}(\alpha)$ and the $T = 0$ gap $\Delta(\delta(0),\alpha)$ varies with frustration in both gapless and gapped phases. The magnetic susceptibility $\chi(T,\alpha)$ at $T > T_{SP}$ can be used to identify physical realizations of spin-Peierls systems. The $\alpha = 1/2$ chain illustrates the characteristic BOW features of a regular chain with a large singlet-triplet gap and electronic dimerization.