ShantanuT01/DACTYL-Pretraining huggingface dataset:
Kerr black holes with synchronised scalar hair and azimuthal harmonic index $m>1$ are constructed and studied. The corresponding domain of existence has a broader frequency range than the fundamental $m=1$ family; moreover, larger ADM masses, $M$ and angular momenta $J$ are allowed. Amongst other salient features, non-uniqueness of solutions for fixed global quantities is observed: solutions with the same $M$ and $J$ co-exist, for consecutive values of $m$, and the ones with larger $m$ are always entropically favoured. Our analysis demonstrates, moreover, the qualitative universality of various features observed for $m=1$ solutions, such as the shape of the domain of existence, the typology of ergo-regions, and the horizon geometry, which is studied through its isometric embedding in Euclidean 3-space.
Pruitt's estimates on the expectation and the distribution of the time taken by a random walk to exit a ball of radius r are extended to the infinite dimensional setting. It is shown that they separate into two pairs of estimates depending on whether the space is type 2 or cotype 2. It is further shown that these estimates characterize type 2 and cotype 2 spaces.
Based on the theory of M-matrix and Perron-Frobenius theorem, we provide some criteria to justify the convergence of the regime-switching diffusion processes in Wasserstein distances. The cost function we used to define the Wasserstein distance is not necessarily bounded. The continuous time Markov chains with finite and countable state space are all studied. To deal with the countable state space, we put forward a finite partition method. The boundedness for state-dependent regime-switching diffusions in an infinite state space is also studied.
The development of high-resolution imaging methods such as electron and scanning probe microscopy and atomic probe tomography have provided a wealth of information on structure and functionalities of solids. The availability of this data in turn necessitates development of approaches to derive quantitative physical information, much like the development of scattering methods in the early XX century which have given one of the most powerful tools in condensed matter physics arsenal. Here, we argue that this transition requires adapting classical macroscopic definitions, that can in turn enable fundamentally new opportunities in understanding physics and chemistry. For example, many macroscopic definitions such as symmetry can be introduced locally only in a Bayesian sense, balancing the prior knowledge of materials' physics and experimental data to yield posterior probability distributions. At the same time, a wealth of local data allows fundamentally new approaches for the description of solids based on construction of statistical and physical generative models, akin to Ginzburg-Landau thermodynamic models. Finally, we note that availability of observational data opens pathways towards exploring causal mechanisms underpinning solid structure and functionality.
We report on the aftermath of a magnetar outburst from the young, high-magnetic-field radio pulsar PSR J1119-6127 that occurred on 2016 July 27. We present the results of a monitoring campaign using the Neil Gehrels Swift X-ray Telescope, NuSTAR, and XMM-Newton. After reaching a peak luminosity of ~300 times the quiescent luminosity, the pulsar's X-ray flux declined by factor of ~50 on a time scale of several months. The X-ray spectra are well described by a blackbody and a hard power-law tail. After an initial rapid decline during the first day of the outburst, we observe the blackbody temperature rising from kT = 0.9 keV to 1.05 keV during the first two weeks of the outburst, before cooling to 0.9 keV. During this time, the blackbody radius decreases monotonically by a factor of ~4 over a span of nearly 200 days. We also report a heretofore unseen highly pulsed hard X-ray emission component, which fades on a similar timescale to the soft X-ray flux, as predicted by models of relaxation of magnetospheric current twists. The previously reported spin-up glitch which accompanied this outburst was followed by a period of enhanced and erratic torque, leading to a net spin-down of $\sim3.5\times10^{-4}$ Hz, a factor of ~24 over-recovery. We suggest that this and other radiatively loud magnetar-type glitch recoveries are dominated by magnetospheric processes, in contrast to conventional radio pulsar glitch recoveries which are dominated by internal physics.
We present an analysis of the use of the Darwin-Fowler approximation in connection with the statistical IPM, by comparing the results of our recent studies with the occupation number approach (OCN) and some traditional statistical independent particle model (IPM) approaches. The analysis of level density works based on the statistical IPM reveals that the use of the the Darwin-Fowler approximation, in some of them, is theoretically inconsistent and some of their results should rather be considered as theoretical coincidences with other consistent approaches, than proofs of their validity. We conclude that, in general, the use of the Darwin-Fowler approximation with the statistical IPM should be used criteriously or, if possible, avoided altogether and suggest that the combinatorial IPM approaches have important advantages over the other models and formalisms analyzed in this paper, especially regarding the consistency of the microscopic description of the nuclear structure and dynamics of non highly excited systems.
We analyze the performance of a quantum repeater protocol based on single trapped ions. At each node, single trapped ions embedded into high finesse cavities emit single photons whose polarization is entangled with the ion state. A specific detection of two photons at a central station located half-way between two nodes heralds the entanglement of two remote ions. Entanglement can be extended to long distances by applying successive entanglement swapping operations based on two-ion gate operations that have already been demonstrated experimentally with high precision. Our calculation shows that the distribution rate of entanglement achievable with such an ion-based quantum repeater protocol is higher by orders of magnitude than the rates that are achievable with the best known schemes based on atomic ensemble memories and linear optics. The main reason is that for trapped ions the entanglement swapping operations are performed deterministically, in contrast to success probabilities below 50 percent per swapping with linear optics. The scheme requires efficient collection of the emitted photons, which can be achieved with cavities, and efficient conversion of their wavelength, which can be done via stimulated parametric down-conversion. We also suggest how to realize temporal multiplexing, which offers additional significant speed-ups in entanglement distribution, with trapped ions.
When magnetic properties are analysed in a TEM using the technique of electron magnetic circular dichroism (EMCD), one of the critical parameters is the sample orientation, and this, independently on the chosen acquisition geometry. Since small orientation changes can have a strong impact on the EMCD measurement, it is experimentally non trivial to measure the EMCD signal as a function of sample orientation. The classical EMCD experimental setup requires to tilt the crystal in a 2 beam orientation and to acquire two electron energy loss spectra at two conjugate scattering angles. The effect of a mistilt from the perfect 2-beam orientation on the measured EMCD signals has not been explored yet due to different experimental constraints. In order to maintain the exact sample location and orientation for the acquisition of the EMCD signal, we have developed a methodology to simultaneously map the quantitative EMCD signals and the local orientation of the crystal. We analyse, both experimentally and with simulations, how the measured magnetic signals evolve with a change in the crystal tilt from the exact 2-beam orientation. Based on this analysis, we establish an accurate relationship between the crystal orientations and the EMCD signals. Our results demonstrate that a small crystal tilt away from the 2-beam orientation can significantly alter the strength and the distribution of the EMCD signals. From an optimisation of the crystal orientation, we obtain quantitative EMCD measurements.
We study the birational geometry of some moduli spaces of abelian varieties with extra structure: in particular, with a symmetric theta structure and an odd theta characteristic. For a $(d_1,d_2)$-polarized abelian surface, we show how the parities of the $d_i$ influence the relation between canonical level structures and symmetric theta structures. For certain values of $d_1$ and $d_2$, a theta characteristic is needed in order to define Theta-null maps. We use these Theta-null maps and preceding work of other authors on the representations of the Heisenberg group to study the birational geometry and the Kodaira dimension of these moduli spaces.
We study the problem of best approximations of a vector $\alpha\in{\mathbb R}^n$ by rational vectors of a lattice $\Lambda\subset {\mathbb R}^n$ whose common denominator is bounded. To this end we introduce successive minima for a periodic lattice structure and extend some classical results from geometry of numbers to this structure. This leads to bounds for the best approximation problem which generalize and improve former results.
A strong edge coloring of a graph is a proper edge coloring where the edges at distance at most two receive distinct colors. It is known that every planar graph with maximum degree D has a strong edge coloring with at most 4D + 4 colors. We show that 3D + 6 colors suffice if the graph has girth 6, and 3D colors suffice if the girth is at least 7. Moreover, we show that cubic planar graphs with girth at least 6 can be strongly edge colored with at most 9 colors.
The dense wind environment (or circumstellar medium) may be ubiquitous for the regular Type II supernovae (SNe) before the explosion, the interaction of which with the SN ejecta could result in a wind breakout event. The shock generated by the interaction of the SN ejecta and the wind can accelerate the protons and subsequently the high-energy gamma-rays and neutrinos could arise from the inelastic pp collisions. In this work, we present the detailed calculations of gamma-ray and neutrino production for the regular Type II SNe. The calculation is executed by applying time-dependent evolutions of dynamic and proton distribution so that the emission could be shown at different times. Our results show, for the SN 2013fs-like wind environment, the multi-GeV and ~ few-100 TeV gamma-rays are detectable with a time window of several days at <~ 2-3 Mpc by Fermi/LAT and CTA during the ejecta-wind interaction, respectively, and can be detected at a further distance if the wind environment is denser. Besides, we found the contribution of the wind breakouts of regular Type II SNe to diffuse neutrino flux is subdominant by assuming all Type II SNe are SN 2013fs-like, whereas for a denser wind environment the contribution could be conspicuous above 300TeV.
Galactic bars can affect the evolution of galaxies by redistributing gas in galaxies, possibly contributing to the cessation of star formation. Recent works point to 'bar quenching' playing an important role in massive disk galaxies like the Milky Way.   We construct the largest ever sample of gas rich and strongly barred disc galaxies with resolved HI observations making use of both the Giant Meter Radio Telescope (GMRT) and the Karl Jansky Very Large Array (VLA) to collect data. This sample, called HIRB (HI Rich Barred) galaxies, were identified with Galaxy Zoo - to find galaxies hosting a strong bar, and the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) blind HI survey- to identify a high HI content.   We measure gas fractions, HI morphology and kinematics in each galaxy, and use archival optical data from the Sloan Digital Sky Survey (SDSS) to reveal star-formation histories and bar properties. HIRB galaxies presented here support a picture where bar quenching is playing, or will play an important role in their evolution. They also support models which show how the presence of cold gas delays and slows the development of strong bars. The galaxies with the lowest gas fractions (still high for their mass) show clear HI holes, dynamical advanced bars and low star formation rates, those with the highest gas fractions show little impact from their bar on the HI morphology, and are actively star-forming. How such unusual galaxies came to be is an open question.   Several of the HIRBs have local gas rich companions. Tidal interactions with these lower mass galaxies could result in an early triggering of the bar and/or accretion of HI between them. The role of environment in the evolution of the HIRB galaxies will be explored in a future paper.
Starting from the origin of Einstein general relativity (GR) the request of Mach on the theory's structure has been the core of the foundational debate. That problem is strictly connected with the nature of the mass-energy equivalence. It is well known that this is exactly the key point that Einstein used to realize a metric theory of gravitation having an unequalled beauty and elegance. On the other hand, the current requirements of particle physics and the open questions within extended gravity theories request a better understanding of Equivalence Principle (EP). The MOND theory by Milgrom proposes a modification of Newtonian dynamics and we consider a direct coupling between the Ricci curvature scalar and the matter Lagrangian showing that a non geodesic ratio m_{i}/m_{g} can be fixed and that Milgrom acceleration is retrieved at low energies.
We obtain a structure theorem for the nonproperness set $S_f$ of a nonsingular polynomial mapping $f:\mathbb{C}^n \to \mathbb{C}^n$. Jelonek's results on $S_f$ and our result show that if $f$ is a counterexample to the Jacobian conjecture, then $S_f$ is a hypersurface such that $S_f\cap Z \neq \emptyset$, for any $Z\subset \mathbb{C}^n$ biregular to $\mathbb{C}^{n-1}$ and $Z = h^{-1}(0)$ for a polynomial submersion $h: \mathbb{C}^n \to \mathbb{C}$. Also, we present topological approaches to the Jacobian conjecture in $\mathbb{C}^n$.
Temperature-dependent FAR-infrared reflectivity spectra of partially ordered magnetodielectric La2CoMnO6 is presented, from room temperature up to 675 K. A clear first-ordered structural phase transition (SPT) from a monoclinic structure with P2_1/n symmetry to a rhombohedral phase with R-3 symmetry was evidenced from the behaviour of polar phonon modes at TC~590 K. The temperature dependences of the transversal and longitudinal phonon branches, dielectric strengths, and damping of the strongest dielectric modes confirm the significant contribution of the phonon modes on the SPT, and revealed an important lattice anharmonicity, particularly for the low frequency modes. In addition, these investigations showed that structural ordering does not inhibit the SPT, and provided valuable information towards the polar phonons, their implications on intrinsic dielectric constant in double perovskites and in related compounds.
We report observations of white-light ejecta in the low corona, for two X-class flares on the 2013 May 13, using data from the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory. At least two distinct kinds of sources appeared (chromospheric and coronal), in the early and later phases of flare development, in addition to the white-light footpoint sources commonly observed in the lower atmosphere. The gradual emissions have a clear identification with the classical loop-prominence system, but are brighter than expected and possibly seen here in the continuum rather than line emission. We find the HMI flux exceeds the radio/X-ray interpolation of the bremsstrahlung produced in the flare soft X-ray sources by at least one order of magnitude. This implies the participation of cooler sources that can produce free-bound continua and possibly line emission detectable by HMI. One of the early sources dynamically resembles "coronal rain", appearing at a maximum apparent height and moving toward the photosphere at an apparent constant projected speed of 134 $\pm$ 8 $\mathrm{km s^{-1}}$. Not much literature exists on the detection of optical continuum sources above the limb of the Sun by non-coronagraphic instruments, and these observations have potential implications for our basic understanding of flare development, since visible observations can in principle provide high spatial and temporal resolution.
Observations have shown that massive star-forming clumps are present in the internal structure of high-redshift galaxies. One way to study these clumps in detail with a higher spatial resolution is by exploiting the power of strong gravitational lensing which stretches images on the sky. In this work, we present an analysis of the clumpy galaxy A68-HLS115 at $z=1.5858$, located behind the cluster Abell 68, but strongly lensed by a cluster galaxy member. Resolved observations with SINFONI/VLT in the near-infrared show Ha, Hb, [NII], and [OIII] emission lines. Combined with images covering the B band to the far-infrared and CO(2-1) observations, this makes this galaxy one of the only sources for which such multi-band observations are available and for which it is possible to study the properties of resolved star-forming clumps and to perform a detailed analysis of the integrated properties, kinematics, and metallicity. We obtain a stability of $\upsilon_{rot}/\sigma_0 = 2.73$ by modeling the kinematics, which means that the galaxy is dominated by rotation, but this ratio also indicates that the disk is marginally stable. We find a high intrinsic velocity dispersion of $80\pm10$ km s$^{-1}$ that could be explained by the high gas fraction of $f_{gas}=0.75\pm0.15$ observed in this galaxy. This high $f_{gas}$ and the observed sSFR of $\rm 3.12 \, Gyr^{-1}$ suggest that the disk turbulence and instabilities are mostly regulated by incoming gas. The direct measure of the Toomre stability criterion of $Q_{crit}=0.70$ could also indicate the presence of a quasi-stable thick disk. Finally, we identify three clumps in the Ha map which have similar velocity dispersions, metallicities, and seem to be embedded in the rotating disk. These three clumps contribute together to $40\%$ on the SFR(Ha) of the galaxy and show a SFR density about $100$ times higher than HII regions in the local Universe.
A general framework for an emergent universe scenario has been given which makes use of an equation of state. The general features of the model have also been studied and possible primordial composition of the universe have been suggested.
In this note I mainly focus on the neutrino physics part in my talk and report the most recent progress made in \cite{YLW0}. It is seen that the Majorana features of neutrinos and SO(3) gauge flavor symmetry can simultaneously explain the smallness of neutrino masses and nearly tri-bimaximal neutrino mixing when combining together with the mechanism of approximate global U(1) family symmetry. The mixing angle $\theta_{13}$ and CP-violating phase are in general nonzero and testable experimentally at the allowed sensitivity. The model also predicts the existence of vector-like Majorana neutrinos and charged leptons as well as new Higgs bosons, some of them can be light and explored at the LHC and ILC.
Shock wave theory was first studied for gas dynamics, for which shocks appear as compression waves. A shock wave is characterized as a sharp transition, even discontinuity in the flow. In fact, shocks appear in many different physical situation and represent strong nonlinearity of the physical processes. Important progresses have been made on shock wave theory in recent years. We will survey the topics for which much more remain to be made. These include the effects of reactions, dissipations and relaxation, shock waves for interacting particles and Boltzmann equation, and multi-dimensional gas flows.
We formulate the Secant Conjecture, which is a generalization of the Shapiro Conjecture for Grassmannians. It asserts that an intersection of Schubert varieties in a Grassmannian is transverse with all points real, if the flags defining the Schubert varieties are secant along disjoint intervals of a rational normal curve. We present theoretical evidence for it as well as computational evidence obtained in over one terahertz-year of computing, and we discuss some phenomena we observed in our data.
We investigate the 1/f noise properties of epitaxial graphene devices at low temperatures as a function of temperature, current and magnetic flux density. At low currents, an exponential decay of the 1/f noise power spectral density with increasing temperature is observed that indicates mesoscopic conductance fluctuations as the origin of 1/f noise at temperatures below 50 K. At higher currents, deviations from the typical quadratic current dependence and the exponential temperature dependence occur as a result of nonequilibrium conditions due to current heating. By applying the theory of Kubakaddi [S. S. Kubakaddi, Phys. Rev. B 79, 075417 (2009)], a model describing the 1/f noise power spectral density of nonequilibrium mesoscopic conductance fluctuations in epitaxial graphene is developed and used to determine the energy loss rate per carrier. In the regime of Shubnikov-de Haas oscillations a strong increase of 1/f noise is observed, which we attribute to an additional conductance fluctuation mechanism due to localized states in quantizing magnetic fields. When the device enters the regime of quantized Hall resistance, the 1/f noise vanishes. It reappears if the current is increased and the quantum Hall breakdown sets in.
Manipulation of octahedral distortion at atomic length scale is an effective means to tune the physical ground states of functional oxides. Previous work demonstrates that epitaxial strain and film thickness are variable parameters to modify the octahedral rotation and tilt. However, selective control of bonding geometry by structural propagation from adjacent layers is rarely studied. Here we propose a new route to tune the ferromagnetic response in SrRuO3 (SRO) ultrathin layers by oxygen coordination of adjacent SrCuO2 (SCO) layers. The infinite-layered CuO2 in SCO exhibits a structural transformation from "planar-type" to "chain-type" as reducing film thickness. These two orientations dramatically modify the polyhedral connectivity at the interface, thus altering the octahedral distortion of SRO. The local structural variation changes the spin state of Ru and hybridization strength between Ru 4d and O 2p orbitals, leading to a significant change in the magnetoresistance and anomalous Hall resistivity of SRO layers. These findings could launch further investigations into adaptive control of magnetoelectric properties in quantum oxide heterostructures using oxygen coordination.
The first stars ended the cosmic Dark Ages and created the first heavy elements necessary for the formation of planets and life. The properties of these stars remain uncertain, and it may be decades before individual Pop III stars are directly observed. Their masses, however, can be inferred from their supernova explosions, which may soon be found in both deep-field surveys by JWST and in all-sky surveys by WFIRST. We have performed radiation hydrodynamical simulations of the near infrared signals of Pop III pair-instability supernovae in realistic circumstellar environments with Lyman absorption by the neutral intergalactic medium. We find that JWST and WFIRST will detect these explosions out to z ~ 30 and 20, respectively, unveiling the first generation of stars in the universe.