ShantanuT01/DACTYL-Pretraining huggingface dataset:
We investigate galactic-scale outflowing winds in 72 star-forming galaxies at z~1 in the Extended Groth Strip. Galaxies were selected from the DEEP2 survey and follow-up LRIS spectroscopy was obtained covering SiII, CIV, FeII, MgII, and MgI lines in the rest-frame ultraviolet. Using GALEX, HST, and Spitzer imaging, we examine galaxies on a per-object basis in order to understand both the prevalence of galactic winds at z~1 and the star-forming and structural properties of objects experiencing outflows. Gas velocities, measured from the centroids of FeII interstellar absorption lines, span the interval [-217, +155] km/s. We find that ~40% (10%) of the sample exhibits blueshifted FeII lines at the 1-sigma (3-sigma) level. We also measure maximal outflow velocities using the profiles of the FeII and MgII lines, and show that MgII frequently traces higher velocity gas than FeII. Quantitative morphological parameters derived from the HST imaging suggest that mergers are not a prerequisite for driving outflows. More face-on galaxies also show stronger winds than highly-inclined systems, consistent with the canonical picture of winds emanating perpendicular to galactic disks. Using star-formation rates calculated from GALEX data, and areas estimated from HST imaging, we detect a ~3-sigma correlation between outflow velocity and star-formation rate surface density, but only a weak (~1-sigma) trend between outflow velocity and star-formation rate. Higher resolution data are needed in order to test the scaling relations between outflow velocity and both star-formation rate and star-formation rate surface density predicted by theory.
We consider the effect of the Sudakov factor in photon-initiated processes, corresponding to the no branching probability for the initial-state photon. We demonstrate how such a factor follows simply from the solution of the DGLAP equation for the photon PDF, and is therefore included automatically by this. We use this result to argue that the appropriate scale for the QED coupling $\alpha$ associated with an initial-state photon is not the virtuality of the photon, but rather the factorization scale at which the photon PDF is evaluated, and therefore that the use of the on-shell renormalization scheme is not appropriate for such processes. We also discuss exclusive photon-initiated processes, and demonstrate that no explicit Sudakov factor is required in this case.
I review some interesting features of massive gravity in two maximally symmetric backgrounds: Anti de Sitter space and Minkowski space. While massive gravity in AdS can be seen as a spontaneously broken, UV safe theory, no such interpretation exists yet in the flat-space case. Here, I point out the problems encountered in trying to find such completion, and possible mechanisms to overcome them.
VLA images of the Sickle and Pistol H II regions near the Galactic center at 3.6 and 6 cm reveal six point sources in the region where the dense Quintuplet stellar cluster is located. The spectral indices of five of these sources between 6 cm and 3.6 cm have values of alpha = +0.5 to +0.8, consistent with the interpretation that the radio sources correspond to ionized stellar winds of the massive stars in this cluster. The radio source associated with the Pistol Star shows alpha = -0.4 +/- 0.2, consistent with a flat or slightly non-thermal spectrum.
We obtain general upper bounds of the sizes and the numbers of Jordan blocks for the eigenvalues $\lambda \not= 1$ in the monodromies at infinity of polynomial maps.
In this paper, we compute the special values of $L$-functions at $s=1$ of some theta products of weight $3$, and express them in terms of special values of generalized hypergeometric functions.
Tropical geometry is a relatively recent field in mathematics created as a simplified model for certain problems in algebraic geometry. We introduce the definition of abstract and planar tropical curves as well as their properties, including combinatorial type and degree. We also talk about the moduli space, a geometric object that parameterizes all possible types of abstract or planar tropical curves subject to certain conditions. Our research focuses on the moduli spaces of planar tropical curves of genus one, arbitrary degree d and any number of marked, unbounded edges. We prove that these moduli spaces are connected.
Let $C$ be a hyperelliptic curve embedded in its Jacobian $J$ via an Abel-Jacobi map. We compute the scheme structure of the Hilbert scheme component of $\textrm{Hilb}_J$ containing the Abel-Jacobi curve as a point. We relate the result to the ramification (and to the fibres) of the Torelli morphism $\mathcal M_g\rightarrow \mathcal A_g$ along the hyperelliptic locus. As an application, we determine the scheme structure of the moduli space of Picard sheaves (introduced by Mukai) on a hyperelliptic Jacobian.
N point particles move within a billiard table made of two circular cavities connected by a straight channel. The usual billiard dynamics is modified so that it remains deterministic, phase space volumes preserving and time reversal invariant. Particles move in straight lines and are elastically reflected at the boundary of the table, as usual, but those in a channel that are moving away from a cavity invert their motion (rebound), if their number exceeds a given threshold T. When the geometrical parameters of the billiard table are fixed, this mechanism gives rise to non--equilibrium phase transitions in the large N limit: letting T/N decrease, the homogeneous particle distribution abruptly turns into a stationary inhomogeneous one. The equivalence with a modified Ehrenfest two urn model, motivated by the ergodicity of the billiard with no rebound, allows us to obtain analytical results that accurately describe the numerical billiard simulation results. Thus, a stochastic exactly solvable model that exhibits non-equilibrium phase transitions is also introduced.
This report summarizes the results of the 'Spectroscopy in the Era of LSST' workshop held April 11-12, 2013 in Tucson, Arizona. At the workshop, there were breakout sessions covering four broad science topics. These were: time domain science, Galactic structure and stellar populations, galaxies and AGN, and dark energy and cosmology. We present the science cases discussed in these breakout sessions and provide a synthesis of highly desired capabilities that meet needs across all four broad topics. We also present a table that will be useful to characterize the needs of specific science cases in a format that provides a general framework for discussion of future spectroscopic capabilities.
We have determined chemical abundances and radial velocities for stars in the field of the zeta Sculptoris cluster. We find that the cluster metal deficiency previously found from UBV photometry is too high; the cluster overall metallicity, [Fe/H]=+0.24, is about 70% higher than the solar value. The chemical abundance pattern is unusual: the Ni/Fe ratio is significantly lower than typical for field stars with similar Fe and Ca abundances, and the cluster may also be deficient in the alpha element Si. For its age, the cluster is unusually far from the galactic disk, approximately 240 pc. The adopted heliocentric cluster radial velocity, +3.9 km/s, shows that it is close to its maximum distance from the galactic plane. We suggest that the zeta Sculptoris cluster was formed in the galactic disk 45 Myr ago by the interaction of a high velocity cloud with the interstellar medium, and that its formation may be connected with that of Gould's Belt. (Table3, postscript figures and text available by anonymous ftp from "chiron.astro.uu.se" in directory pub/articles/atmos/P90)
We show that there is a constant $k$ such that when $r \geq 2$ and $m \geq r^k$, the complete $r$-partite graph $K_{m*r}$ has a non-colorable list assignment $L$ such that $|L(v)| \geq \frac{7}{750}r\ln m$ for all $v$ and such that $|L(u) \cap L(v)| \leq \left\lfloor \frac{2r}{r-1} \right\rfloor$ whenever $u \neq v$. This roughly extends a result of Alon to the context of "choosability with separation", introduced by Kratochv\'il, Tuza, and Voigt.
We study the action of time dependent canonical and coordinate transformations in phase space quantum mechanics. We extend the covariant formulation of the theory by providing a formalism that is fully invariant under both standard and time dependent coordinate transformations. This result considerably enlarges the set of possible phase space representations of quantum mechanics and makes it possible to construct a causal representation for the distributional sector of Wigner quantum mechanics.
We extend the phase-field approach to model the solidification of faceted materials. Our approach consists of using an approximate gamma-plot with rounded cusps that can approach arbitrarily closely the true gamma-plot with sharp cusps that correspond to faceted orientations. The phase-field equations are solved in the thin-interface limit with local equilibrium at the solid-liquid interface [A. Karma and W.-J. Rappel, Phys. Rev. E53, R3017 (1996)]. The convergence of our approach is first demonstrated for equilibrium shapes. The growth of faceted needle crystals in an undercooled melt is then studied as a function of undercooling and the cusp amplitude delta for a gamma-plot of the form 1+delta(|sin(theta)|+|cos(theta)|). The phase-field results are consistent with the scaling law "Lambda inversely proportional to the square root of V" observed experimentally, where Lambda is the facet length and V is the growth rate. In addition, the variation of V and Lambda with delta is found to be reasonably well predicted by an approximate sharp-interface analytical theory that includes capillary effects and assumes circular and parabolic forms for the front and trailing rough parts of the needle crystal, respectively.
Model smoothing is of central importance for obtaining a reliable teacher model in the student-teacher framework, where the teacher generates surrogate supervision signals to train the student. A popular model smoothing method is the Temporal Moving Average (TMA), which continuously averages the teacher parameters with the up-to-date student parameters. In this paper, we propose "Spatial Ensemble", a novel model smoothing mechanism in parallel with TMA. Spatial Ensemble randomly picks up a small fragment of the student model to directly replace the corresponding fragment of the teacher model. Consequentially, it stitches different fragments of historical student models into a unity, yielding the "Spatial Ensemble" effect. Spatial Ensemble obtains comparable student-teacher learning performance by itself and demonstrates valuable complementarity with temporal moving average. Their integration, named Spatial-Temporal Smoothing, brings general (sometimes significant) improvement to the student-teacher learning framework on a variety of state-of-the-art methods. For example, based on the self-supervised method BYOL, it yields +0.9% top-1 accuracy improvement on ImageNet, while based on the semi-supervised approach FixMatch, it increases the top-1 accuracy by around +6% on CIFAR-10 when only few training labels are available. Codes and models are available at: https://github.com/tengteng95/Spatial_Ensemble.
To analyze the state of injected carrier streams of different electron sources, we propose to use correlation measurements at a quantum point contact with the different sources connected via chiral edge states to the two inputs. In particular we consider the case of an on-demand single-electron emitter correlated with the carriers incident from a biased normal reservoir, a contact subject to an alternating voltage and a stochastic single electron emitter. The correlation can be viewed as a spectroscopic tool to compare the states of injected particles of different sources. If at the quantum point contact the amplitude profiles of electrons overlap, the noise correlation is suppressed. In the absence of an overlap the noise is roughly the sum of the noise powers due to the electron streams in each input. We show that the electron state emitted from a (dc or ac) biased metallic contact is different from a Lorentzian amplitude electron state emitted by the single electron emitter (a quantum capacitor driven with slow harmonic potential), since with these inputs the noise correlation is not suppressed. In contrast, if quantized voltage pulses are applied to a metallic contact instead of a dc (ac) bias then the noise can be suppressed. We find a noise suppression for multi-electron pulses and for the case of stochastic electron emitters for which the appearance of an electron at the quantum point contact is probabilistic.
Short time scale variations have been reported for a few Miras, including sudden 0.2 magnitude or more brightening in the visual lasting from a few hours to a few days. Are these flashes real? Are they hot? What are they? Almost all the natural time scales for variation in the atmosphere and wind of a Mira variable are months to years long. What could cause such short-term variations? One intriguing possibility is that the variations are associated with the interaction of a Jovian planet with the time-dependent outflow of a Mira wind. Here we discuss observable features of such an interaction in terms of order-of-magnitude estimates and phenomenology, and make one clear prediction requiring observational followup. Future work needs to include both theoretical calculations and the development of systematic methods for searching for such events.
We answer a question raised by Caucher Birkar for singularities of weighted blowups of $\mathbb{A}^n$, if $n\leq 3$.
We establish upper bounds on the blow-up rate of the gradients of solutions of the Lam\'{e} system with partially infinite coefficients in dimensions greater than two as the distance between the surfaces of discontinuity of the coefficients of the system tends to zero.
Bollob\'as and Riordan, in their paper "Metrics for sparse graphs," proposed a number of provocative conjectures extending central results of quasirandom graphs and graph limits to sparse graphs. We refute these conjectures by exhibiting a sequence of graphs with convergent normalized subgraph densities (and pseudorandom $C_4$-counts), but with no limit expressible as a kernel.
On the basis of the Woodhouse causal axiomatics, we show that conformal proper times and an extra variable in addition to those of space and time, precisely and physically identified from experimental examples, together give a physical justification for the `chronometric hypothesis' of general relativity. Indeed, we show that, with a lack of these latter two ingredients, no clock paradox solution exists in which the clock and message functions are solely at the origin of the asymmetry. These proper times originate from a given conformal structure of the spacetime when ascribing different compatible projective structures to each Woodhouse particle, and then, each defines a specific Weylian sheaf structure. In addition, the proper time parameterizations, as two point functions, cannot be defined irrespective of the processes in the relative changes of physical characteristics. These processes are included via path-dependent conformal scale factors, which act like sockets for any kind of physical interaction and also represent the values of the variable associated with the extra dimension. As such, the differential aging differs far beyond the first and second clock effects in Weyl geometries, with the latter finally appearing to not be suitable.
Let $K$ be a field whose characteristic is prime to a fixed integer $n$ with $\mu_n \subset K$, and choose $\omega \in \mu_n$ a primitive $n$th root of unity. Denote the absolute Galois group of $K$ by $\operatorname{Gal}(K)$, and the mod-$n$ central-descending series of $\operatorname{Gal}(K)$ by $\operatorname{Gal}(K)^{(i)}$. Recall that Kummer theory, together with our choice of $\omega$, provides a functorial isomorphism between $\operatorname{Gal}(K)/\operatorname{Gal}(K)^{(2)}$ and $\operatorname{Hom}(K^\times,\mathbb{Z}/n)$. Analogously to Kummer theory, in this note we use the Merkurjev-Suslin theorem to construct a continuous, functorial and explicit embedding $\operatorname{Gal}(K)^{(2)}/\operatorname{Gal}(K)^{(3)} \hookrightarrow \operatorname{Fun}(K\smallsetminus\{0,1\},(\mathbb Z/n)^2)$, where $\operatorname{Fun}(K\smallsetminus\{0,1\},(\mathbb Z/n)^2)$ denotes the group of $(\mathbb Z/n)^2$-valued functions on $K\smallsetminus\{0,1\}$. We explicitly determine the functions associated to the image of commutators and $n$th powers of elements of $\operatorname{Gal}(K)$ under this embedding. We then apply this theory to prove some new results concerning relations between elements in abelian-by-central Galois groups.
We calculate ground-state properties of a many-quark system in the string-flip model using variational Monte Carlo methods. The many-body potential energy of the system is determined by finding the optimal grouping of quarks into hadrons. This (optimal) assignment problem is solved by using the stochastic optimization technique of simulated annealing. Results are presented for the energy and length-scale for confinement as a function of density. These results show how quarks clustering decreases with density and characterize the nuclear- to quark-matter transition. We compare our results to a previously published work with a similar model which uses, instead, a pairing approach to the optimization problem.
We present a photometric catalog of 45 massive star clusters in the nuclear starburst of M 83 (NGC 5236), observed with the Hubble Space Telescope WFPC2, in both broad-band (F300W, F547M, and F814W) and narrow-band (F656N and F487N) filters. By comparing the photometry to theoretical population synthesis models, we estimate the age and mass of each cluster. We find that over 75% of the star clusters more massive than 2*10^4 Msun in the central 300 pc of M 83 are less than 10 Myr old. Among the clusters younger than 10 Myr and more massive than 5*10^3 Msun, 70% are between 5 and 7 Myr old. We list an additional 330 clusters that are detected in our F300W images, but not in the shallower F547M and F814W images. The clusters are distributed throughout a semicircular annulus that identifies the active region in the galaxy core, between 50 and 130 pc from the optical center of M 83. Clusters younger than 5 Myr are preferentially found along the perimeter of the semicircular annulus. We suggest that the 5-7 Myr population has evacuated much of the interstellar material from the active ringlet region, and that star formation is continuing along the edges of the region.
We demonstrate that an A-type antiferromagnetic (AFM) state of Pr{0.5}Sr{0.5}MnO{3} exhibits a novel charge ordering which governs the transport property. This charge ordering is stripe-like, being characterized by a wave vector q ~ (0,0,0.3) with very anisotropic correlation parallel and perpendicular to the stripe direction. This charge ordering is specific to the manganites with relatively wide one-electron band width (W) which often exhibit a metallic A-type AFM state, and should be strictly distinguished from the CE-type checkerboard-like charge ordering which is commonly observed in manganites with narrower W such as La{1-x}Ca{x}MnO{3} and Pr{1-x}Ca{x}MnO{3}.
We present yet another new family of masks for high-contrast imaging as required for the to-be-built terrestrial planet finder space telescope. The ``best'' design involves a square entrance pupil having a 4-vane spider, a square image-plane mask containing a plus-sign shaped occulter to block the starlight inside 0.6 lambda/D, and a Lyot-plane mask consisting of a rectangular array of rectangular opennings. Using Fraunhofer analysis, we show that the optical system can image a planet 10^{-10} times as bright as an on-axis star in four rectangular regions given by {(xi,zeta): 1.4 < | xi | < 20, 1.4 < | zeta | < 20}.   Since the design involves an image plane mask, pointing error is an issue. We show that the design can tolerate pointing errors of about 0.05 lambda/D.   The inclusion of a 4-vane spider in the entrance pupil provides the possibility to build a mirror-only on-axis system thereby greatly reducing the negative effects of polarization.   Each of the masks can be realized as two masks consisting of stripes of opaque material with the stripes oriented at right angles to each other. We call these striped masks barcode masks. We show that it is sufficient for the barcode masks by themselves to provide 10^{-5} contrast. This then guarantees that the full system will provide the required 10^{-10} contrast.
The two closest Gamma-Ray Bursts so far detected (GRBs 980425 & 060218) were both under-luminous, spectrally soft, long duration bursts with smooth, single-peaked light curves. Only of the order of 100 GRBs have measured redshifts, and there are, for example, 2704 GRBs in the BATSE catalogue alone. It is therefore plausible that other nearby GRBs have been observed but not identified as relatively nearby. Here we search for statistical correlations between BATSE long duration GRBs and galaxy samples with recession velocities v <= 11,000 km/s (z = 0.0367, ~ 155 Mpc) selected from two catalogues of nearby galaxies. We also examine the correlations using burst sub-samples restricted to those with properties similar to the two known nearby bursts. Our results show correlation of the entire long GRB sample to remain consistent with zero out to the highest radii considered whereas a sub-sample selected to be low fluence, spectrally soft, with smooth single-peaked light curves (177 bursts) demonstrates increased correlation with galaxies within ~ 155 Mpc. The measured correlation (28% +/- 16% of the sample) suggests that BATSE observed between 2 and 9 long duration GRBs per year similar to, and from within similar distances to GRBs 980425 and 060218. This implies an observed local rate density (to BATSE limits) of 700 +/- 360 Gpc^{-3}yr^{-1} within 155 Mpc.
We prove that the vertex degree threshold for tiling $\C_4^3$ (the 3-uniform hypergraph with four vertices and two triples) in a 3-uniform hypergraph on $n\in 4\mathbb N$ vertices is $\binom{n-1}2 - \binom{\frac34 n}2+\frac38n+c$, where $c=1$ if $n\in 8\mathbb N$ and $c=-\frac12$ otherwise. This result is best possible, and is one of the first results on vertex degree conditions for hypergraph tiling.
We review the Consistent Amplitude approach to Quantum Theory and argue that quantum probabilities are explicitly Bayesian. In this approach amplitudes are tools for inference. They codify objective information about how complicated experimental setups are put together from simpler ones. Thus, probabilities may be partially subjective but the amplitudes are not.