Miracle-dz/UniFAR-FTUs huggingface dataset:
Spontaneous symmetry breaking of rapidly rotating stars in general relativity: influence of the 3D-shift vector

An analytical scheme and a numerical method in order to study the effects of general relativity on the viscosity driven secular bar mode instability of rapidly rotating stars are presented. The approach consists in perturbing an axisymmetric and stationary configuration and studying its evolution by constructing a series of triaxial quasi-equilibrium configurations. These are obtained by solution of an approximate set of field equations where only the dominant non-axisymmetric terms are taken into account. The progress with respect to our former investigation consists in a higher relativistic order of the non-axisymmetric terms included into the computation, namely the fully three-dimensional treatment of the vector part of the space-time metric tensor as opposed to the scalar part, solely, in the former case. The scheme is applied to rotating stars built on a polytropic equation of state and compared to our previous results. The 3D-vector part turns out to inhibit the symmetry breaking efficiently. Nevertheless, the bar mode instability is still possible for an astrophysically relevant mass of M_ns=1.4 M_sun when a stiff polytropic equation of state with an adiabatic index of gamma=2.5 is employed. Triaxial neutron stars may be efficient emitters of gravitational waves and are thus potentially interesting sources for the forthcoming laser interferometric gravitational wave detectors such as LIGO, VIRGO and GEO600. From a numerical point of view, the solution of the three-dimensional minimal-distortion shift vector equation in spherical coordinates is an important achievement of our code.
Global structure of Choptuik's critical solution in scalar field collapse

At the threshold of black hole formation in the gravitational collapse of a scalar field a naked singularity is formed through a universal critical solution that is discretely self-similar. We study the global spacetime structure of this solution. It is spherically symmetric, discretely self-similar, regular at the center to the past of the singularity, and regular at the past light cone of the singularity. At the future light cone of the singularity, which is also a Cauchy horizon, the curvature is finite and continuous but not differentiable. To the future of the Cauchy horizon the solution is not unique, but depends on a free function (the null data coming out of the naked singularity). There is a unique continuation with a regular center (which is self-similar). All other self-similar continuations have a central timelike singularity with negative mass.
Finding and pinpointing exceptional points of an open quantum system

An exceptional point (EP) is a point in the parameter space of an open quantum system in which the two eigenstates of the effectively non-Hermitian system coalesce and a topological effect can be observed. In this work we use the properties of the energy eigenvalues near the EP at three different points in order to find the exact EP location in the parameter space. This method does not require the two parameters of the system to be grouped as a single complex parameter, so it can easily be applied to Floquet operators. Finally, it is shown that by applying the Hellmann–Feynman theorem, the EP position can be obtained from a single point. The benefits of using the 3-point approach or the 1-point approach are discussed. These simple techniques may be of use in the search for new EPs in various physical systems. To demonstrate the utility of the method, we find an EP for an H+2 molecule driven by a monochromatic laser and for a laser-driven Gaussian potential.
The astrophysical consequences of intervening galaxy gas on fast radio bursts

We adopt and analyze results on the incidence and physical properties of damped Ly$\alpha$ systems (DLAs) to predict the astrophysical impact of gas in galaxies on observations of Fast Radio Bursts (FRBs). Three DLA measures form the basis of this analysis: (i) the HI column density distribution, parameterized as a double power-law; (ii) the incidence of DLAs with redshift (derived here), $\ell(z)=A+B \arctan(z-C)$ with $A=0. 236_{-0.021}^{+0.016}, B=0.168_{-0.017}^{+0.010}, C=2. 87_{-0.13}^{+0.17}$ and (iii) the electron density, parameterized as a log-normal deviate with mean $10^{-2.6} cm^{-3}$ and dispersion 0.3dex. Synthesizing these results, we estimate that the average rest-frame dispersion measure from the neutral medium of a single, intersecting galaxy is DM$^{NM}_{DLA}=0.25$ pc/cm^3. Analysis of AlIII and CII* absorption limits the putative warm ionized medium to contribute DM$^{WIM}_{DLA}<20$pc/cm^3. Given the low incidence of DLAs, we find that a population of FRBs at z=2 will incur DM(z=2)=0.01 pc/cm^3 on average, with a 99% c.l. upper bound of 0.22 pc/cm^3. Assuming that turbulence of the ISM in external galaxies is qualitatively similar to our Galaxy, we estimate that the angular broadening of an FRB by intersecting galaxies is negligible ($\theta<0.1$mas). The temporal broadening is also predicted to be small, $\tau \approx 0.3$ms for a z=1 galaxy intersecting a z=2 FRB for an observing frequency of $\nu=1$GHz. Even with $\nu=600$MHz, the fraction of sightlines broadened beyond 25ms is only approximately 0.1%. We conclude that gas within the ISM of intervening galaxies has a minor effect on the detection of FRBs and their resultant DM distributions. Download the repository at this https URL to repeat and extend the calculations presented here.
Sum rules for the T -odd fragmentation functions

The conservation of the intrinsic transverse momentum during parton fragmentation imposes nontrivial constraints on T-odd fragmentation functions. These significantly enhance the differences between the favored and unfavored fragmentation functions, which could be relevant to understand the azimuthal asymmetries of charged pion production observed recently by the HERMES Collaboration.
Full-wave calculation of sheared poloidal flow driven by high-harmonic ion Bernstein waves in tokamak plasmas

A full-wave, one-dimensional spectral model is developed to study sheared poloidal flow driven by high-harmonic ion Bernstein waves (IBWs) in tokamak plasmas. The local plasma conductivity is corrected to lowest order in ρ/L where ρ is the ion Larmor radius and L is the equilibrium scale length. This correction takes into account gradients in equilibrium quantities and is necessary for conservation of energy. It is equivalent to the “odd-order derivative” terms in finite difference models. No assumption is made regarding the smallness of the ion Larmor radius relative to wavelength, and results are applicable to all orders in k⊥ρ where k⊥ is the perpendicular wave number. Previous numerical results for flow drive have relied on expansions in k⊥ρ, and are thus limited to cyclotron harmonics of two and below. In this article, we consider higher-harmonic cases corresponding to recent IBW flow drive experiments on the Tokamak Fusion Test Reactor [B. P. LeBlanc, R. E. Bell, S. Bernabei et al., Phys. Rev. Lett.
A New single-dynamical-scalar-field model of dark energy

A new single-dynamical-scalar-field model of dark energy is proposed, in which either higher derivative terms nor structures of extra dimension are needed. With the help of a fixed background vector field, the parameter for the effective equation of state of dark energy may cross $w=-1$ in the evolution of the universe. After suitable choice of the potential, the crossing $w=-1$ and transition from decelerating to accelerating occur at $z\approx 0.2$ and $z\approx 1.7$, respectively.
Ground-state properties of a dilute Bose-Fermi mixture

We investigate the properties of a dilute boson-fermion mixture at zero temperature. The ground-state energy of the system is calculated to second order in the Bose-Fermi coupling constant. The Green's function formalism is applied to obtain results for the effect of Bose-Fermi interactions on the spectrum of phonon excitations, the momentum distribution, the condensate fraction, and the superfluid density of the bosonic component. A quantitative discussion of these effects is presented in the case of mixtures with attractive interspecies interaction.
Fly-by encounters between two planetary systems I: Solar system analogues

Stars formed in clusters can encounter other stars at close distances. In typical open clusters in the Solar neighbourhood containing hundreds or thousands of member stars, 10–20 per cent of Solar-mass member stars are expected to encounter another star at distances closer than 100 au. These close encounters strongly perturb the planetary systems, directly causing ejection of planets or their capture by the intruding star, as well as exciting the orbits. Using extensive N-body simulations, we study such fly-by encounters between two Solar system analogues, each with four giant planets from Jupiter to Neptune. We quantify the rates of loss and capture immediately after the encounter, e.g. the Neptune analogue is lost in one in four encounters within 100 au, and captured by the flying-by star in 1 in 12 encounters. We then perform long-term (up to 1 Gyr) simulations investigating the ensuing post-encounter evolution. We show that large numbers of planets are removed from systems due to planet–planet interactions and that captured planets further enhance the system instability. While encounters can initially leave a planetary system containing more planets by inserting additional ones, the long-term instability causes a net reduction in planet number. A captured planet ends up on a retrograde orbit in half of the runs in which it survives for 1Gyr; also, a planet bound to its original host star but flipped during the encounter may survive. Thus, encounters between planetary systems are a channel to create counter-rotating planets, This would happen in around 1 per cent of systems, and such planets are potentially detectable through astrometry or direct imaging.
Distribution function of dark matter

There is good evidence from N-body simulations that the velocity distribution in the outer parts of halos is radially anisotropic, with the kinetic energy in the radial direction roughly equal to the sum of that in the two tangential directions. We provide a simple algorithm to generate such cosmologically important distribution functions. Introducing r{sub E}(E), the radius of the largest orbit of a particle with energy E, we show how to write down almost trivially a distribution function of the form f(E,L)=L{sup -1}g(r{sub E}) for any spherical model - including the 'universal' halo density law (Navarro-Frenk-White profile). We in addition give the generic form of the distribution function for any model with a local density power-law index {alpha} and anisotropy parameter {beta} and provide limiting forms appropriate for the central parts and envelopes of dark matter halos. From those, we argue that, regardless of the anisotropy, the density falloff at large radii must evolve to {rho}{approx}r{sup -4} or steeper ultimately.
Low-field anomalous magnetic phase in the kagome-lattice shandite C o 3 S n 2 S 2

The magnetization process of single crystals of the metallic kagome ferromagnet Co3Sn2S2 was carefully measured via magnetization and AC susceptibility. Field-dependent anomalous transitions in the magnetization indicate a low-field unconventionally ordered phase stabilized just below TC. The magnetic phase diagrams in applied fields along different crystallographic directions were determined. The magnetic relaxation process studied in frequencies covering five orders of magnitude from 0.01 to 1000 Hz indicates characteristic relaxation times of several seconds at the boarders of the anomalous phase. Our results arise a lot of questions about the nature of Co3Sn2S2 magnetic states.
Spatial modelling of extreme sea‐levels

The problem of estimating the probability of extreme sea-levels along a coastline has received little attention. Most of the existing analyses are univariate approaches that are applied independently to data from individual sites. We present a spatial extension of the methods that integrates information from the data sites and exploits knowledge of the spatial variation of the tidal and surge constituents of the sea-level along a coastline, to produce estimates at any coastal location. We illustrate the method by application to the UK east coast providing a set of design level estimates along the entire coastline.
Current modulation of a hygroscopic insulator organic field-effect transistor

We have fabricated solution processable polymer transistors with high conductivity, requiring only a few volts for obtaining good current modulation. The devices can be fabricated and operated in air and the operation is greatly enhanced in humid atmosphere. Devices reach an On∕Off ratio of about 600 and a subthreshold swing of 500mV per decade operating on voltages less than 2V. In this letter the mechanism behind the current modulation is investigated, and we show that the current is modulated through ion-assisted oxidation and reduction of the semiconductor by ions moving vertically in the insulator material to the transistor channel.
16 μm Imaging around the Hubble Deep Field-North with the Spitzer IRS

We present a pilot study of 16 μm imaging within the GOODS northern field. Observations were obtained using the "peak-up" imaging capability of the Spitzer IRS. We survey 35 arcmin2 to an average 3 σ depth of 0.075 mJy and detect 149 sources. The survey partially overlaps the area imaged at 15 μm by the ISO, and we demonstrate that our photometry and galaxy number counts are consistent with its measurements. We infer the total infrared luminosity of 16 μm detections using a comparison to local templates and find a wide range of LIR, from ~109 to 1012 L☉. Approximately of the detected sources have counterparts in the Chandra 2 Ms catalog, and we show that the hard-band (2-8 keV) detected sources are likely to have strong active galactic nucleus (AGN) contributions to the X-ray flux. The ultradeep sensitivity of Chandra implies that some X-ray detections may be purely starbursting objects. We examine the 16 to 24 μm flux ratio and conclude that it shows evidence for the detection of redshifted polycyclic aromatic hydrocarbon (PAH) emission at z ~ 0.5 and z > 0.8.
Typical performance of regular low-density parity-check codes over general symmetric channels

Typical performance of low-density parity-check (LDPC) codes over a general binary-input output-symmetric memoryless channel is investigated using methods of statistical mechanics. Relationship between the free energy in statistical-mechanics approach and the mutual information used in the information-theory literature is established within a general framework; Gallager and MacKay-Neal codes are studied as specific examples of LDPC codes. It is shown that basic properties of these codes known for particular channels, including their potential to saturate Shannon's bound, hold for general symmetric channels. The binary-input additive-white-Gaussian-noise channel and the binary-input Laplace channel are considered as specific channel models.
Internal languages of diagrams of ∞ -toposes

Homotopy type theory (HoTT) is a handy language for reasoning about an ∞ -topos. However, sometimes we have more than one ∞ -toposes related to each other by some functors, in which case plain HoTT is not sufficiently rich because the actions of the functors are not internalized. In this talk, we consider a certain class of diagrams of ∞ -toposes for which plain HoTT remains a sufficiently rich internal language. We show that a special form of an inverse diagram of ∞ -toposes is reconstructed internally to its oplax limit via lex modalities. Then plain HoTT as an internal language of the oplax limit can be used for reasoning about the original diagram.
Frequency response of headphones measured in free field and diffuse field by loudness comparison

Coupler measurement of headphone frequency response may be incorrect at high and low frequencies [T. Hirahara and K. Ueda, J. Acoust. Soc. Am. Suppl. 1 87, S142 (1990)]. Since sound pressure near the eardrum is difficult to measure physically, a psychophysical method was employed to assess real ear frequency response of headphones. Loudness comparisons were performed by four subjects, under two experimental conditions: free field (anechoic room) and diffuse field (reverberation room). These conditions were run to check the influence of field characteristics on the reliability of the measurements. Each subject adjusted the headphone level of critical band noise bursts until they were equally loud as those from a reference loudspeaker (7 dB SPL). Measurement scatter was smaller in the diffuse field than in the free field. One hypothesis to explain this result is that head movement causes less change in level in a diffuse field than in a free field. Support for this comes from measurement of the SPL distribu.
Taming the tachyon in cubic string field theory

We give evidence based on level-truncation computations that the rolling tachyon in cubic open string field theory (CSFT) has a well-defined but wildly oscillatory time-dependent solution which goes as et for t? We show that a field redefinition taking the CSFT effective tachyon action to the analogous boundary string field theory (BSFT) action takes the oscillatory CSFT solution to the pure exponential solution et of the BSFT action.
HFB theory for nuclei near the drip-lines: continuum coupling

We have developed a new HFB code that specifically addresses nuclear structure physics near the driplines. The HFB equations are solved on a two-dimensional lattice for axially symmetric even-even nuclei using B-Spline techniques. The quasiparticle energy spectrum is obtained by direct diagonalization of the HFB lattice Hamiltonian with LAPACK. The energy spectrum extends high into the continuum, up to several thousand MeV. Calculations with Skyrme forces and (density-dependent) delta pairing interactions are now underway.
DIS structure functions in the NLO approximation of the Parton Reggeization Approach

The main ideas of the NLO calculations in Parton Reggeization Approach are illustrated on the example of the simplest NLO subprocess, which contributes to DIS: γ * + R → q + q The double counting with the LO contribution γ * + Q → q is resolved. The problem of matching of the NLO results for single-scale observables in PRA on the corresponding NLO results in Collinear Parton Model is considered. In the developed framework, the usual NLO PDFs in the M S -scheme can be consistently used as the collinear input for the NLO calculation in PRA.
[Ar III]/[O III] and [S III]/[O III]: well-behaved oxygen abundance indicators for HII regions and star forming galaxies

We propose two statistical methods to derive oxygen abundances in HII regions and star forming galaxies and calibrate them with a sample of several hundred giant HII regions in spiral and blue compact galaxies as well as of galaxies from the Sloan Digital Sky Survey. We show the advantages of our new abundance indicators over previous ones.
Noise-resilient preparation of quantum many-body ground states

Certain quantum many-body ground states can be prepared by a large-depth quantum circuit consisting of geometrically local gates. In the presence of noise, local expectation values deviate from the correct value at most by an amount comparable to the noise rate. This happens if the action of the noiseless circuit, restricted to certain subsystems, rapidly mixes local observables up to a small correction. The encoding circuit for the surface code is given as an example.
Hybrid Ray-FDTD Moving Window Approach to Pulse Propagation

A moving window finite difference time domain method is developed to simulate the propagation of electromagnetic pulses over large distances. Both Eulerian and Lagrangian approaches to solving Maxwell's equations in a moving window are obtained and contrasted. The Lagrangian approach is shown to be superior for electromagnetic pulse propagation; it is demonstrated that dispersion-free numerical propagation can be achieved with the Lagrangian approach. Examples of propagation in homogeneous and inhomogeneous media, and scattering from a interface between two media are considered. The scattering results are achieved with a window splitting approach in which the original incident pulse window is frozen at the interface and new windows are generated after the interface interactions occur that move with the reflected and transmitted pulses. The simulation results are shown to be accurate and physically appealing.
Merger rate of primordial black-hole binaries

Primordial black holes (PBHs) have long been a candidate for the elusive dark matter (DM), and remain poorly constrained in the ~20-100 Msun mass range. PBH binaries were recently suggested as the possible source of LIGO's first detections. In this paper, we thoroughly revisit existing estimates of the merger rate of PBH binaries. We compute the probability distribution of orbital parameters for PBH binaries formed in the early Universe, accounting for tidal torquing by all other PBHs, as well as standard large-scale adiabatic perturbations. We then check whether the orbital parameters of PBH binaries formed in the early Universe can be significantly affected between formation and merger. Our analytic estimates indicate that the tidal field of halos and interactions with other PBHs, as well as dynamical friction by unbound standard DM particles, do not do significant work on nor torque PBH binaries. We estimate the torque due to baryon accretion to be much weaker than previous calculations, albeit possibly large enough to significantly affect the eccentricity of typical PBH binaries. We also revisit the PBH-binary merger rate resulting from gravitational capture in present-day halos, accounting for Poisson fluctuations. If binaries formed in the early Universe survive to the present time, as suggested by our analytic estimates, they dominate the total PBH merger rate. Moreover, this merger rate would be orders of magnitude larger than LIGO's current upper limits if PBHs make a significant fraction of the dark matter. As a consequence, LIGO would constrain ~10-300 Msun PBHs to constitute no more than ~1% of the dark matter. To make this conclusion fully robust, though, numerical study of several complex astrophysical processes - such as the formation of the first PBH halos and how they may affect PBH binaries, as well as the accretion of gas onto an extremely eccentric binary - is needed.
IGR J17062–6143 Is an Accreting Millisecond X-Ray Pulsar

We present the discovery of 163.65 Hz X-ray pulsations from IGR J17062−6143 in the only observation obtained from the source with the Rossi X-ray Timing Explorer. This detection makes IGR J17062−6143 the lowest-frequency accreting millisecond X-ray pulsar presently known. The pulsations are detected in the 2–12 keV band with an overall significance of 4. 3σ and an observed pulsed amplitude of 5.54% ± 0.67% (in this band). Both dynamic power spectral and coherent phase timing analysis indicate that the pulsation frequency is decreasing during the ≈1.2 ks observation in a manner consistent with orbital motion of the neutron star. Because the observation interval is short, we cannot precisely measure the orbital period; however, periods shorter than 17 minutes are excluded at 90% confidence. For the range of acceptable circular orbits the inferred binary mass function substantially overlaps the observed range for the AMXP population as a whole.