ShantanuT01/DACTYL-Pretraining huggingface dataset:
Weak lensing has become an increasingly important tool in cosmology and the use of galaxy shapes to measure cosmic shear has become routine. The weak-lensing distortion tensor contains two other effects in addition to the two components of shear: the convergence and rotation. The rotation mode is not measurable using the standard cosmic shear estimators based on galaxy shapes, as there is no information on the original shapes of the images before they were lensed. Due to this, no estimator has been proposed for the rotation mode in cosmological weak-lensing surveys, and the rotation mode has never been constrained. Here, we derive an estimator for this quantity, which is based on the use of radio polarisation measurements of the intrinsic position angles of galaxies. The rotation mode can be sourced by physics beyond $\Lambda$CDM, and also offers the chance to perform consistency checks of $\Lambda$CDM and of weak-lensing surveys themselves. We present simulations of this estimator and show that, for the pedagogical example of cosmic string spectra, this estimator could detect a signal that is consistent with the constraints from Planck. We examine the connection between the rotation mode and the shear $B$-modes and thus how this estimator could help control systematics in future radio weak-lensing surveys.
Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non--active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope (EIT) on the {\it Solar and Heliospheric Observatory} ({\it SOHO}), in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is in general determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament ``barbs'' is opposite in sign to and dominates that of the overlying arcade.
Rest-frame mid- to far-infrared spectroscopy is a powerful tool to study how galaxies formed and evolved, because a major part of their evolution occurs in heavily dust enshrouded environments, especially at the so-called Cosmic Noon. Using the calibrations of IR lines we predict the expected fluxes of lines and features, with the aim to measure the star formation rate and the Black Hole Accretion rate in intermediate to high redshift galaxies. The launch of the James Webb Space Telescope will allow us a deep investigation of both the SF and the BHA obscured processes as a function of cosmic time. We assess the spectral lines and features that can be detected by JWST-MIRI in galaxies and Active Galactic Nuclei up to redshift z= 3. We confirm the fine-structure lines of [MgIV]4.49um and [ArVI]4.53um as good BHA rate tracers for the 1<z<3 range, and we propose the [NeVI]7.65um line as the best tracer for redshifts of z<1.5. We suggest the use of the [ArII]6.98um and [ArIII]8.99um lines to measure the SF rate, for z<3 and z<2. At higher redshifts, the PAH features at 6.2um and 7.7um can be observed at z<3 and z<2.7 respectively. Rest-frame far-IR spectroscopy is currently being collected in high redshift galaxies (z>3) with the Atacama Large Millimeter Array. We confirm that the [CII]158um line is a good tracer of the SF rate and can in most cases (0.9<z<2 and 3<z<9) be observed, and we propose the use of the combination of [OIII]88um and [OI]145um lines as an alternative SF rate tracer, that can be detected above z>3. We conclude, however, that the current and foreseen facilities will not be able to cover properly the peak of the obscured SF and BHA activities at the Cosmic Noon of galaxy evolution and a new IR space telescope, actively cooled to obtain very good sensitivities, covering the full IR spectral range from about 10um to 300um, will be needed.
We give bounds on the distribution and fragmentation functions that appear at leading order in deep inelastic 1-particle inclusive leptoproduction or in Drell-Yan processes. These bounds simply follow from positivity of the defining matrix elements and are an important guidance in estimating the magnitude of the azimuthal and spin asymmetries in these processes.
Markovian regime decoherence effects in quantum computers are studied in terms of the fidelity for the situation where the number of qubits N becomes large. A general expression giving the decoherence time scale in terms of Markovian relaxation elements and expectation values of products of system fluctuation operators is obtained, which could also be applied to study decoherence in other macroscopic systems such as Bose condensates and superconductors. A standard circuit model quantum computer involving three-state lambda system ionic qubits is considered, with qubits localised around well-separated positions via trapping potentials. The centre of mass vibrations of the qubits act as a reservoir. Coherent one and two qubit gating processes are controlled by time dependent localised classical electromagnetic fields that address specific qubits, the two qubit gating processes being facilitated by a cavity mode ancilla, which permits state interchange between qubits. With a suitable choice of parameters, it is found that the decoherence time can be made essentially independent of N.
We describe a new class of systems exhibiting return point memory (RPM) that are different from those discussed before in the context of ferromagnets. We show numerically that one dimensional random Ising antiferromagnets have RPM, when configurations evolve from a large field. However, RPM is violated when started from some stable configurations at finite field unlike in the ferromagnetic case. This implies that the standard approach to understanding ferromagnetic RPM systems will fail for this case. We also demonstrate RPM with a set of variables that keep track of spin flips at each site. Conventional RPM for the spin configuration is a projection of this result, suggesting that spin flip variables might be a more fundamental representation of the dynamics. We also present a mapping that embeds the antiferromagnetic chain in a two dimensional ferromagnetic model, and prove RPM for spin exchange dynamics in the interior of the chain with this mapping.
We study the effect of an electrostatic coupling between a scanning tunneling microscope tip and a Luttinger liquid wire on the tunneling current and noise between the two. Solving the Dyson equations non perturbatively for a local interaction potential, we derive the Green's functions associated to the wire and to the tip. Interestingly, the electrostatic coupling leads to the existence of new correlators, which we call mixed Green's functions, which are correlators between the bosonic fields of the wire and the tip. Next, we calculate the transport properties up to second order with the amplitude of the tunnel transfer: the tunnel current is strongly reduced by the presence of screening. The zero-frequency noise is modified in a similar way, but the Fano factor remains unchanged. We also consider the effect of the screening on the asymmetry of the finite-frequency non-symmetrized noise and on the conductance.
A new type of quantum size effect (QSE) oscillations is predicted for films with a relatively large correlation radius of surface inhomogeneities. The effect replaces usual QSE for random inhomogeneities with Gaussian and exponential power spectra. The well-pronounced oscillations of conductivity $\sigma $ as a function of channel width $L$ separate two distinct regions with different indices in the power-law dependence $\sigma (L) $. The oscillations are explained and their positions identified. The effect is reminiscent of magnetic breakthrough and can simplify observation of QSE in metals.
More than half a century ago Penrose asked: are the superfluid and solid state of matter mutually exclusive or do there exist "supersolid" materials where the atoms form a regular lattice and simultaneously flow without friction? Recent experiments provide evidence that supersolid behavior indeed exists in Helium-4 -- the most quantum material known in Nature. In this paper we show that large local strain in the vicinity of crystalline defects is the origin of supersolidity in Helium-4. Although ideal crystals of Helium-4 are not supersolid, the gap for vacancy creation closes when applying a moderate stress. While a homogeneous system simply becomes unstable at this point, the stressed core of crystalline defects (dislocations and grain boundaries) undergoes a radical transformation and can become superfluid.
We have studied the kinetics of cluster formation for dynamical systems of dimensions up to $n=8$ interacting through elastic collisions or coalescence. These systems could serve as possible models for gas kinetics, polymerization and self-assembly. In the case of elastic collisions, we found that the cluster size probability distribution undergoes a phase transition at a critical time which can be predicted from the average time between collisions. This enables forecasting of rare events based on limited statistical sampling of the collision dynamics over short time windows. The analysis was extended to L$^p$-normed spaces ($p=1,...,\infty$) to allow for some amount of interpenetration or volume exclusion. The results for the elastic collisions are consistent with previously published low-dimensional results in that a power law is observed for the empirical cluster size distribution at the critical time. We found that the same power law also exists for all dimensions $n=2,...,8$, 2D L$^p$ norms, and even for coalescing collisions in 2D. This broad universality in behavior may be indicative of a more fundamental process governing the growth of clusters.
We present 426 epochs of optical monitoring data spanning 1000 days from December 2003 to June 2006 for the gravitationally lensed quasar SDSS J1004+4112. The time delay between the A and B images is 38.4+/-2.0 days in the expected sense that B leads A and the overall time ordering is C-B-A-D-E. The measured delay invalidates all published models. The models failed because they neglected the perturbations from cluster member galaxies. Models including the galaxies can fit the data well, but strong conclusions about the cluster mass distribution should await the measurement of the longer, and less substructure sensitive, delays of the C and D images. For these images, a CB delay of 681+/-15 days is plausible but requires confirmation, while CB and AD delays of >560 days and > 800 days are required. We clearly detect microlensing of the A/B images, with the delay-corrected flux ratios changing from B-A=0.44+/-0.01 mag in the first season to 0.29+/-0.01 mag in the second season and 0.32+/-0.01 mag in the third season.
All integer solutions $\left(M,a,c\right)$ to the problem of the sums of $M$ consecutive cubed integers $\left(a+i\right)^{3}$ ($a>1$, $0\leq i\leq M-1$) equaling squared integers $c^{2}$ are found by decomposing the product of the difference and sum of the triangular numbers of $\left(a+M-1\right)$ and $\left(a-1\right)$ in the product of their greatest common divisor $g$ and remaining square factors $\delta^{2}$ and $\sigma^{2}$, yielding $c=g\delta\sigma$. Further, the condition that $g$ must be integer for several particular and general cases yield generalized Pell equations whose solutions allow to find all integer solutions $\left(M,a,c\right)$ showing that these solutions appear recurrently. In particular, it is found that there always exist at least one solution for the cases of all odd values of $M$, of all odd integer square values of $a$, and of all even values of $M$ equal to twice an integer square.
Generally, the Schwarzschild black hole was proved stable through two different methods: the mode-decomposition method and the integral method. In the paper, we show the integral method can only apply to the initial data vanishing at both the horizon and the spatial infinity. It can not treat the initial data only vanishing at the spatial infinity. We give an example to show the misleading information caused by the use of the tortoise coordinates in the perturbation equations. Subsequently, the perturbation equation in the Schwarzschild coordinates is shown not sufficient for the stable study.
Audio tagging aims to infer descriptive labels from audio clips. Audio tagging is challenging due to the limited size of data and noisy labels. In this paper, we describe our solution for the DCASE 2018 Task 2 general audio tagging challenge. The contributions of our solution include: We investigated a variety of convolutional neural network architectures to solve the audio tagging task. Statistical features are applied to capture statistical patterns of audio features to improve the classification performance. Ensemble learning is applied to ensemble the outputs from the deep classifiers to utilize complementary information. a sample re-weight strategy is employed for ensemble training to address the noisy label problem. Our system achieves a mean average precision (mAP@3) of 0.958, outperforming the baseline system of 0.704. Our system ranked the 1st and 4th out of 558 submissions in the public and private leaderboard of DCASE 2018 Task 2 challenge. Our codes are available at https://github.com/Cocoxili/DCASE2018Task2/.
The detailed study of nuclear regions of galaxies is important because it can help understanding the active galactic nucleus (AGN) feedback mechanisms, the connections between the nuclei and their host galaxies, and ultimately the galaxy formation processes. We present the analysis of an optical data cube of the central region of the galaxy NGC 2442, obtained with the integral field unit (IFU) of the Gemini Multi-Object Spectrograph (GMOS). We also performed a multiwavelength analysis, with Chandra data, XMM--Newton and NuSTAR spectra, and Hubble Space Telescope (HST) images. The analysis revealed that the nuclear emission is consistent with a Low Ionization Nuclear Emission-line Region (LINER) associated with a highly obscured compact hard X-ray source, indicating a Compton-thick AGN. The HST image in the F658N filter (H$\alpha$) reveals an arched structure corresponding to the walls of the ionization cone of the AGN. The gas kinematic pattern and the high gas velocity dispersion values in the same region of the ionization cone suggest an outflow emission. The stellar archaeology results indicate the presence of only old stellar populations ($\sim$ 10 Gyr), with high metallicity (z = 0.02 and 0.05), and the absence of recent star formation in the central region of NGC 2442, which is possibly a consequence of the AGN feedback, associated with the detected outflow, shutting off star formation. NGC 2442 is a late-type galaxy similar to the Milky Way, and comparisons show that the main difference between them is the presence of a low-luminosity AGN.
We establish $L^p$, $2\le p\le\infty$ solvability of the Dirichlet boundary value problem for a parabolic equation $u_t-\mbox{div}(A\nabla u)=0$ on time-varying domains with coefficient matrix $A=(a_{ij})$ that satisfy a small Carleson condition. The result is motivated by similar results for the elliptic equation $\mbox{div}(A\nabla u)=0$ that were established previously.
For an integer $k$ at least $2$, and a graph $G$, let $f_k(G)$ be the minimum cardinality of a set $X$ of vertices of $G$ such that $G-X$ has either $k$ vertices of maximum degree or order less than $k$. Caro and Yuster (Discrete Mathematics 310 (2010) 742-747) conjectured that, for every $k$, there is a constant $c_k$ such that $f_k(G)\leq c_k \sqrt{n(G)}$ for every graph $G$. Verifying a conjecture of Caro, Lauri, and Zarb (arXiv:1704.08472v1), we show the best possible result that, if $t$ is a positive integer, and $F$ is a forest of order at most $\frac{1}{6}\left(t^3+6t^2+17t+12\right)$, then $f_2(F)\leq t$. We study $f_3(F)$ for forests $F$ in more detail obtaining similar almost tight results, and we establish upper bounds on $f_k(G)$ for graphs $G$ of girth at least $5$. For graphs $G$ of girth more than $2p$, for $p$ at least $3$, our results imply $f_k(G)=O\left(n(G)^{\frac{p+1}{3p}}\right)$. Finally, we show that, for every fixed $k$, and every given forest $F$, the value of $f_k(F)$ can be determined in polynomial time.
We show how the output of the algorithm to compute modular Galois representations described in our previous article can be certified. We have used this process to compute certified tables of such Galois representations obtained thanks to an improved version of this algorithm, including representations modulo primes up to 31 and representations attached to a newform with non-rational (but of course algebraic) coefficients, which had never been done before. These computations take place in the Jacobian of modular curves of genus up to 26. The resulting data are available on the author's webpage, http://www2.warwick.ac.uk/fac/sci/maths/people/staff/mascot/galreps.
Cranked Relativistic Hartree-Bogoliubov (CRHB) theory is presented as an extension of Relativistic Mean Field theory with pairing correlations to the rotating frame. Pairing correlations are taken into account by a finite range two-body force of Gogny type and approximate particle number projection is performed by Lipkin-Nogami method. This theory is applied to the description of yrast superdeformed rotational bands observed in even-even nuclei of the $A\sim 190$ mass region. Using the well established parameter sets NL1 for the Lagrangian and D1S for the pairing force one obtains a very successful description of data such as kinematic ($J^{(1)}$) and dynamic ($J^{(2)}$) moments of inertia without any adjustment of new parameters. Within the present experimental accuracy the calculated transition quadrupole moments $Q_t$ agree reasonably well with the observed data.
We show that the magnetic moment of a composite multiferroic torsional oscillator can be switched by the electric field. The 180$^o$ switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.
We present a revised analysis of a speculated stellar bridge between the Milky Way dwarf galaxies Leo IV and Leo V. Using data acquired with Subaru/Suprime-Cam over a 1deg x 4deg field encompassing the two satellites and the region in between, we confirm our previous detection of a stellar overdensity between Leo IV and Leo V (de Jong et al. 2010). The larger area coverage and improved depth of our current dataset allow for an improved analysis of the stellar overdensity that had previously appeared to bridge the two galaxies. A main-sequence turn-off feature visible in the stacked colour-magnitude diagram of the contiguously observed Subaru fields reveals an extended stellar structure at a distance of approximately 20 kpc. Its angular proximity to the Virgo overdensity, as well as a good correspondence in distance and metallicity, suggests that the smaller structure we detect may be associated with the much larger Virgo stellar overdensity.
Recently we have presented a hidden variable model of measurements for a qubit where the hidden variable state space dimension is one-half the quantum state manifold dimension. The absence of a short memory (Markov) dynamics is the price paid for this dimensional reduction. The conflict between having the Markov property and achieving the dimensional reduction was proved in [A. Montina, Phys. Rev. A, 77, 022104 (2008)] using an additional hypothesis of trajectory relaxation. Here we analyze in more detail this hypothesis introducing the concept of invertible process and report a proof that makes clearer the role played by the topology of the hidden variable space. This is accomplished by requiring suitable properties of regularity of the conditional probability governing the dynamics. In the case of minimal dimension the set of continuous hidden variables is identified with an object living an N-dimensional Hilbert space, whose dynamics is described by the Schr\"odinger equation. A method for generating the economical non-Markovian model for the qubit is also presented.
We examine X-ray scaling relations for massive halos ($M_{500}>10^{12.3}M_\odot$) in the Simba galaxy formation simulation. The X-ray weighted luminosity, $L_X$ vs. $M_{500}$ has power-law slopes $\approx\frac{5}{3}$ and $\approx\frac{8}{3}$ above and below $10^{13.5} M_{\odot}$, deviating from the self-similarity increasingly to low masses. $T_X-M_{500}$ is self-similar above this mass, and slightly shallower below it. Comparing Simba to observed $T_X$ scalings, we find that $L_X$, $L_X$-weighted [Fe/H], and entropies at $0.1 R_{200}$ ($S_{0.1}$) and $R_{500}$ ($S_{500}$) all match reasonably well. $S_{500}-T_X$ is consistent with self-similar expectations, but $S_{0.1}-T_X$ is shallower at lower $T_X$, suggesting the dominant form of heating moves from gravitational shocks in the outskirts to non-gravitational feedback in the cores of smaller groups. Simba matches observations of $L_X$ versus central galaxy stellar mass $M_*$, predicting the additional trend that star-forming galaxies have higher $L_X(M_*)$. The electron density profiles for $M_{500}>10^{14}M_\odot$ halos show a $\sim 0.1R_{200}$ core, but at lower masses the profiles are flat at all radii. $T_X$ profiles are flat for $M_{500}<10^{13}M_{\odot}$, and increasingly centrally peaked with mass. The resulting entropy profiles are centrally depressed for the highest and lowest mass halos but flatter for intermediate-mass halos, with $S_{\rm core}\approx200-400$ keV cm$^2$. Simba's [Fe/H] profile matches observations in the core but over-predicts at larger radii, suggesting overly widespread metal distribution. We show that Simba's bipolar jet AGN feedback is most responsible for increasingly evacuating lower-mass halos, thereby suppressing core densities and raising core entropies to improve agreement with X-ray scaling relations.
Bimodality is a common feature of globular cluster (GC) color distributions in galaxies. Although it is well known that the GC system of the Milky Way is bimodal in metallicity, this has yet to be directly demonstrated for an elliptical galaxy. We use Lick index measurements from the literature to derive metallicities for 47 GCs in the giant Virgo elliptical galaxy NGC 4472. The resulting distribution shows clear evidence for two metallicity subpopulations of GCs.
Weak solutions to parabolic integro-differential operators of order $\alpha \in (\alpha_0, 2)$ are studied. Local a priori estimates of H\"older norms and a weak Harnack inequality are proved. These results are robust with respect to $\alpha \nearrow 2$. In this sense, the presentation is an extension of Moser's result in 1971.
Let $Q = \mathbb P^1 x \mathbb P^1$ and let $X\subset Q$ be a 0-dimensional scheme. This paper is a first step towards the characterization of Hilbert functions of 0- dimensional schemes in $Q$. In particular we show how, under some conditions on $X$, its Hilbert function changes when we add points to $X$ lying on a $(1,0)$ or $(0, 1)$-line. As a particular case we show also that if $X$ is ACM this result holds without any additional hypothesis.