Miracle-dz/UniFAR-FTUs huggingface dataset:
Local and global variations of the fine-structure constant

Using the Bekenstein-Sandvik-Barrow-Magueijo (BSBM) varying-a theory, with dark matter dominated by magnetic energy, and the spherical collapse model for cosmological structure formation, we have studied the effects of the dark-energy equation of state and the coupling of a to the matter fields on the space and time evolution of a. We have compared its evolution inside virialized overdensities with that in the cosmological background, using the standard (A = 0) cold dark matter (CDM) model of structure formation and the dark-energy modification, wCDM. We find that, independently of the model of structure formation one considers, there is always a difference between the value of a in an overdensity and in the background. In a standard CDM (SCDM) model, this difference is the same, independent of the virialization redshift of the overdense region. In the case of a dark-energy CDM (wCDM) model, especially at low redshifts, the difference depends on the time when virialization occurs and the equation of state of the dark energy. At high redshifts, when the wCDM model becomes asymptotically equivalent to the SCDM one, the difference is constant. At low redshifts, when dark energy starts to dominate the cosmological expansion, the difference between a in a cluster and in the background grows. The inclusion of the effects of inhomogeneity leads naturally to no observable local time variations of a on Earth and in our Galaxy even though time variations can be significant on quasar scales. The inclusion of the effects of inhomogeneous cosmological evolution are necessary if terrestrial and solar-system bounds on the time variation of the fine-structure 'constant' are to be correctly compared with extragalactic data.
Testing Brans-Dicke gravity using the Einstein telescope

Gravitational radiation is an excellent field for testing theories of gravity in strong gravitational fields. The current observations on the gravitational-wave (GW) bursts by LIGO have already placed various constraints on the alternative theories of gravity. In this paper, we investigate the possible bounds which could be placed on the Brans-Dicke gravity using GW detection from inspiralling compact binaries with the proposed Einstein Telescope, a third-generation GW detector. We first calculate in details the waveforms of gravitational radiation in the lowest post-Newtonian approximation, including the tensor and scalar fields, which can be divided into the three polarization modes, i.e. "plus mode", "cross mode" and "breathing mode". Applying the stationary phase approximation, we obtain their Fourier transforms, and derive the correction terms in amplitude, phase and polarization of GWs, relative to the corresponding results in General Relativity. Imposing the noise level of Einstein Telescope, we find that the GW detection from inspiralling compact binaries, composed of a neutron star and a black hole, can place stringent constraints on the Brans-Dicke gravity. The bound on the coupling constant $\omega_{\rm BD}$ depends on the mass, sky-position, orbital angle, polarization angle, luminosity distance, redshift distribution and total observed number $N_{\rm GW}$ of the binary systems. Taking into account all the burst events up to redshift $z=5$, we find that the bound could be $\omega_{\rm BD}\gtrsim 10^{6}\times(N_{\rm GW}/10^4)^{1/2}$. Even for the conservative estimation with $10^{4}$ observed events, the bound is still more than one order tighter than the current limit from Solar System experiments. So, we conclude that Einstein Telescope will provide a powerful platform to test alternative theories of gravity.
Laboratory investigations of the bending rheology of floating saline ice, and physical mechanisms of wave damping, in the HSVA ice tank

An experiment on the propagation of flexural-gravity waves was performed in the HSVA ice tank. Physical characteristics of the water-ice system were measured in different locations in the tank during the tests, with a number of sensors deployed in the water, on the ice and in the air. Water velocity was measured with an acoustic doppler velocimeter (ADV) and an acoustic doppler current profiler (ADCP); wave amplitudes were measured with ultrasonic sensors and the optical system Qualisys; in-plane deformations of the ice and the temperature of the ice and water were measured by fiber optic sensors, and acoustic emissions were recorded with compressional crystal sensors. All together 61 tests were performed, with ice thicknesses of 3 cm and 5 cm. The experimental setup and selected results of the tests are discussed in this paper. We show that cyclic motion of the ice along the tank, imitating ice drift, causes an increase in wave damping. We also show that the formation of non-through cracks in the ice, caused by the action of waves, increases wave damping.
DUST IN CLUSTERS: SEPARATING THE CONTRIBUTION OF GALAXIES AND INTRACLUSTER MEDIA

We have analyzed a sample of 327 clusters of galaxies, spanning the range of 0.06–0.70 in redshift. Strong constraints on their mean intracluster emission of dust have been obtained using maps and catalogs from the Herschel MerMES project; within a radius of 5 arcmin centered in each cluster, the 95% C.L. limits obtained are 86.6, 48.2, and 30.9 mJy at the observed frequencies of 250, 350, and 500 μm. From these restrictions, and assuming physical parameters typical of interstellar media in the Milky Way, we have obtained tight upper limits on the visual extinction of background galaxies due to the intracluster media (ICM): AV(95% C.L.) ≲ 10−3 mag. Strong constraints are also obtained for the mass of such dust; for instance, using the data at 350 μm we establish a 95% upper limit of <109 M⊙ within a circle with a radius of 5 arcmin centered in the clusters. This corresponds to a fraction of the total mass of the clusters of 9.5 × 10−6, and indicates a deficiency in the gas-to-dust ratio in the ICM by about three orders of magnitude in relation to the value found in the Milky Way. Computing the total infrared luminosity of the clusters in three ranges of redshift (0.05–0.24, 0.24–0.42, and 0.42–0.71) and two ranges of mass (<1014 and >1014 M⊙), respectively, a strong evolution of luminosity in redshift (L ∼ z1.5) for both ranges of masses is found. The results indicate a strong declining in star formation rate with time in the last ∼6 Gyr.
Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant

We present the UBV(RI)KC light curves of the Type Ia supernova SN 1998bu, which appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo I group that has a Cepheid-based distance. Our photometry allows us to calculate the absolute magnitude and reddening of this supernova. These data, when combined with measurements of the four other well-observed supernovae with Cepheid-based distances, allow us to calculate the Hubble constant with respect to the Hubble flow defined by the distant Calán/Tololo Type Ia sample. We find a Hubble constant of 63.9 ± 2.2(internal) ± 3.5(external) km s-1 Mpc-1, consistent with most previous estimates based on Type Ia supernovae. We note that the two well-observed Type Ia supernovae in Fornax, if placed at the Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too faint with respect to the Calán/Tololo sample calibrated with the five Type Ia supernovae with Cepheid distances to the host galaxies.
Longer gaps between values of binary quadratic forms

Let $s_1, s_2, \ldots$ be the sequence of positive integers, arranged in increasing order, that are representable by any binary quadratic form of fixed discriminant $D$. We show that \[ \limsup_{n \rightarrow \infty} \frac{s_{n+1}-s_n}{\log s_n} \ge \frac{\varphi(|D|)}{2|D|(1+\log \varphi(|D|))}\gg \frac{1}{\log \log |D|}, \] improving a lower bound of $\frac{1}{|D|}$ of Richards (1982). In the special case of sums of two squares, we improve Richards's bound of $1/4$ to $\frac{195}{449}=0.434\ldots$. We also generalize Richards's result in another direction and establish a lower bound on long gaps between sums of two squares in certain sparse sequences.
Convergence in Density in Finite Time Windows and the Skorohod Representation

According to the Dudley-Wichura extension of the Skorohod representation theorem, convergence in distribution to a limit in a separable set is equivalent to the existence of a coupling with elements converging a.s. in the metric. A density analogue of this theorem says that a sequence of probability densities on a general measurable space has a probability density as a pointwise lower limit if and only if there exists a coupling with elements converging a.s. in the discrete metric. In this paper the discrete-metric theorem is extended to stochastic processes considered in a widening time window. The extension is then used to prove the separability version of the Skorohod representation theorem.
Commensurability invariance for abelian splittings of right-angled Artin groups, braid groups and loop braid groups

We prove that if a right-angled Artin group $A_\Gamma$ is abstractly commensurable to a group splitting non-trivially as an amalgam or HNN-extension over $\mathbb{Z}^n$, then $A_\Gamma$ must itself split non-trivially over $\mathbb{Z}^k$ for some $k\le n$. Consequently, if two right-angled Artin groups $A_\Gamma$ and $A_\Delta$ are commensurable and $\Gamma$ has no separating $k$-cliques for any $k\le n$ then neither does $\Delta$, so "smallest size of separating clique" is a commensurability invariant. We also discuss some implications for issues of quasi-isometry. Using similar methods we also prove that for $n\ge 4$ the braid group $B_n$ is not abstractly commensurable to any group that splits non-trivially over a "free group-free" subgroup, and the same holds for $n\ge 3$ for the loop braid group $LB_n$. Our approach makes heavy use of the Bieri--Neumann--Strebel invariant.
X-ray spectra of sources in the 13HXMM–Newton/Chandra deep field

We present the X-ray spectra of 86 optically identified sources in the 13^H XMM–Newton/Chandra deep field which have >70 X-ray counts. The majority of these sources have 2–10 keV fluxes between 10^(−1)5 and 5 × 10^(−1)4 erg cm^(−2) s^(−1). The sample consists of 50 broad-line active galactic nuclei (BLAGN), 25 narrow emission-line galaxies (NELGs), six absorption-line galaxies and five Galactic stars. The majority (42/50) of the BLAGN have X-ray spectra which are consistent with a power-law shape. They have a mean photon index 〈Γ〉= 2.0 ± 0.1 and an intrinsic dispersion σ_Γ= 0.4 ± 0.1. Three of the BLAGN show curved spectra, with more emission near the high- and low-energy ends of the spectrum relative to the emission in the 1–2 keV range than can be reproduced by the power-law model. Five BLAGN show a deficit of soft X-rays, indicating absorption. We consider a source to be significantly absorbed if a power-law model fit is rejected with >99 per cent confidence and an absorbed power-law model produces an acceptable fit, or if the best-fitting power law is abnormally hard (Γ < 1). Significant absorption is more common in the NELGs (13/25) and absorption-line galaxies (2/6) than in the BLAGN (5/50), but is not universal in any of these classes of object. The majority of the 20 absorbed sources have X-ray spectra consistent with a simple cold photoelectric absorber, but a significant minority (6/20) require more complex models with either an additional component of soft X-ray emitting plasma, or an ionized absorber. Of the 16 narrow emission- and absorption-line galaxies which do not show evidence for X-ray absorption, only two objects are likely to be powered by star formation, and both have 2–10 keV X-ray luminosities of ≤ 10^(40) erg s^(−1). The X-ray emission in the other 14 unabsorbed NELGs and galaxies is most likely powered by AGN, which are not detected in the optical because they are outshone by their luminous host galaxies. The Galactic stars show multitemperature thermal spectra which peak between 0.5 and 1 keV. Star/AGN discrimination is possible for four of the five stars solely from their X-ray spectra.
A complete sample of radio sources in the North Ecliptic Cap, selected at 38 MHz – III. Further imaging observations and the photometric properties of the sample

Further imaging observations of a sample of radio sources in the North Ecliptic Cap are presented and a number of new identifications are made. Using redshifts from spectroscopic data presented in a companion paper by Lacy et al., the photometric properties of the galaxies in the sample are discussed. It is shown that: (1) out to at least z≈0.6 radio galaxies are good standard candles irrespective of radio luminosity; (2) for 0.6≲z≲1 a large fraction of the sample has magnitudes and colours consistent with a non-evolving giant elliptical, and (3) at higher redshifts, where the R-band samples the rest-frame UV flux, most objects have less UV luminosity than expected if they form their stellar populations at a constant rate from a high redshift to z∼1 in unobscured star-forming regions (assuming an Einstein–de Sitter cosmology). The consequences of these observations are briefly discussed.
Dependence of zinc oxide thin film properties on filtered vacuum arc deposition parameters

The micro-properties (structure and composition) and macro-properties (electrical and optical properties) of zinc oxide thin films deposited on glass substrates using a filtered vacuum arc deposition system were investigated as a function of oxygen pressure (0.37–0.5 Pa) and arc current (100–300 A). The films were polycrystalline and the crystal plane orientation varied with the oxygen pressure and arc current, tending to be aligned parallel to the c-axis. The sizes of the crystallite grains were 10–35 nm. The films were found to be compressively stressed, with stress in the range of −2.5–0 GPa. The stress in any sample decreased as a function of arc current; however, its dependence on the pressure also depended on the applied arc current. The compressive stress in samples deposited with arc current in the range 100–150 A, decreased with the pressure from −2.5 to −1.5 GPa (0.37–0.5 Pa), whereas it increased with the oxygen pressure in samples deposited with arc current ranging from 200–300 A. The compressive stress in all samples deposited with the highest oxygen pressure (0.51 Pa) was in a relatively narrow range of −2.1 to −1.7 GPa. Film composition, determined by x-ray photoelectron spectroscopy, depended weakly on the deposition parameters. All samples had zinc excess, with a typical oxygen to zinc atomic concentration ratio of 0.7–0.8. Film thickness, in the range of 80–780 nm, depended linearly on both the deposition parameters. The electrical resistivity (ρ) of the films was in the range of (1–5) × 10−4 Ωm, depending weakly on the deposition parameters. The electrical resistivity of the films with larger grain size was higher than that of films with smaller grains, whereas it increased with film stress. The optical transmission of the films, expressed by the extinction coefficient, depended strongly on both the deposition parameters (arc current and oxygen pressure). The lowest extinction was obtained with films deposited with higher pressure (P ⩽ 0.5 Pa) and lower arc current (I ⩾ 200 A). The lowest extinction coefficient was ∼4 × 10−4 nm−1 in the visible and the near-IR range of the spectrum. Films with larger grain size and lower stress had a relatively larger extinction coefficient (∼8 × 10−3 nm−1).
A Numerical Simulation of Coronal Waves Interacting with Coronal Holes. I. Basic Features

We have developed a new numerical code that is able to perform 2.5D simulations of a magnetohydrodynamic (MHD) wave propagation in the corona, and its interaction with a low-density region, such as a coronal hole (CH). We show that the impact of the wave on the CH leads to different effects, such as reflection and transmission of the incoming wave, stationary features at the CH boundary, or formation of a density depletion. We present a comprehensive analysis of the morphology and kinematics of primary and secondary waves, i.e., we describe in detail the temporal evolution of density, magnetic field, plasma flow velocity, phase speed, and position of the wave amplitude. Effects like reflection, refraction, and transmission of the wave strongly support the theory that large-scale disturbances in the corona are fast MHD waves and distinguish that theory from the competing pseudo-wave theory. The formation of stationary bright fronts was one of the main reasons for the development of pseudo-waves. Here, we show that stationary bright fronts can be produced by interactions of an MHD wave with a CH. We find secondary waves that are traversing through the CH and we show that one part of these traversing waves leaves the CH again, while another part is being reflected at the CH boundary inside the CH. We observe a density depletion that is moving in the opposite direction of the primary wave propagation. We show that the primary wave pushes the CH boundary to the right, caused by the wave front exerting dynamic pressure on the CH.
Imaginary multiplicative chaos: Moments, regularity and connections to the Ising model

In this article we study imaginary Gaussian multiplicative chaos -- namely a family of random generalized functions which can formally be written as $e^{i X(x)}$, where $X$ is a log-correlated real-valued Gaussian field on $\mathbb{R}^d$, i.e. it has a logarithmic singularity on the diagonal of its covariance. We study basic analytic properties of these random generalized functions, such as what spaces of distributions do these objects live in, along with their basic stochastic properties, such as moment and tail estimates. After this, we discuss connections between imaginary multiplicative chaos and the critical planar Ising model, namely that the scaling limit of the spin field of the so called critical planar XOR-Ising model can be expressed in terms of the cosine of the Gaussian free field, i.e. the real part of an imaginary multiplicative chaos distribution. Moreover, if one adds a magnetic perturbation to the XOR-Ising model, then the scaling limit of the spin field can be expressed in terms of the cosine of the sine-Gordon field, which can also be viewed as the real part of an imaginary multiplicative chaos distribution. The first sections of the article have been written in the style of a review, and we hope that the text will also serve as an introduction to imaginary chaos for an uninitiated reader.
Detailed analysis of the tetraquark potential and flip-flop in SU(3) lattice QCD

We perform the detailed study of the tetraquark (4Q) potential V{sub 4Q} for various QQ-QQ systems in SU(3) lattice QCD with {beta}=6.0 and 16{sup 3}x32 at the quenched level. For about 200 different patterns of 4Q systems, V{sub 4Q} is extracted from the 4Q Wilson loop in 300 gauge configurations, with the smearing method to enhance the ground-state component. We calculate V{sub 4Q} for planar, twisted, asymmetric, and large-size 4Q configurations, respectively. Here, the calculation for large-size 4Q configurations is done by identifying 16{sup 2}x32 as the spatial size and 16 as the temporal one, and the long-distance confinement force is particularly analyzed in terms of the flux-tube picture. When QQ and QQ are well separated, V{sub 4Q} is found to be expressed as the sum of the one-gluon-exchange Coulomb term and multi-Y-type linear term based on the flux-tube picture. When the nearest quark and antiquark pair is spatially close, the system is described as a 'two-meson' state. We observe a flux-tube recombination called a 'flip-flop' between the connected 4Q state and the two-meson state around the level-crossing point. This leads to infrared screening of the long-range color forces between (anti)quarks belonging to different mesons, and results in the absencemore » of the color van der Waals force between two mesons. « less
Critical behaviour in one dimension: unconventional pairing, phase separation, BEC-BCS crossover and magnetic Lifshitz transition

We study the superconducting properties of population-imbalanced ultracold Fermi mixtures in one-dimensional (1D) optical lattices that can be effectively described by the spin-imbalanced attractive Hubbard model (AHM) in the presence of a Zeeman magnetic field. We use the mean-field theory approach to obtain the ground state phase diagrams including some unconventional superconducting phases such as the Fulde--Ferrell--Larkin--Ovchinnikov (FFLO) phase, and the $\eta$ phase (an extremal case of the FFLO phase), both for the case of a fixed chemical potential and for a fixed number of particles. It allows to determine optimal regimes for the FFLO phase as well as $\eta$-pairing stability. We also investigate the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (BEC) with increasing attraction, at $T=0$. Finally, the obtained results show that despite of the occurrence of the Lifshitz transition induced by an external magnetic field, the superconducting state can still exist in the system, at higher magnetic field values.
Assembling the Milky Way Bulge from Globular Clusters: Evidence from the Double Red Clump

Two red clumps (RCs) observed in the color–magnitude diagram of the Milky Way bulge are widely accepted as evidence for an X-shaped structure that originated from the bar instability. A drastically different interpretation has been suggested, however, based on the He-enhanced multiple stellar population phenomenon as is observed in globular clusters (GCs). Because these two scenarios imply very different pictures of the formation of the bulge and elliptical galaxies, understanding the origin of the double RC is of crucial importance. Here we report our discovery that the stars in the two RCs show a significant (>5.3σ) difference in CN-band strength, in stark contrast to that expected in the X-shaped bulge scenario. The difference in CN abundance and the population ratio between the two RCs are comparable to those observed in GCs between the first- and later-generation stars. Because CN-strong stars trace a population with enhanced N, Na, and He abundances that originated in GCs, this is direct evidence that the double RC is due to the multiple population phenomenon, and that a significant population of stars in the Milky Way bulge were assembled from disrupted proto-GCs. Our result also calls for the major revision of the 3D structure of the Milky Way bulge, given that the current view is based on the previous interpretation of the double RC phenomenon.
Bistability in mushroom-type metamaterials

Here, we study the electromagnetic response of asymmetric mushroom-type metamaterials loaded with nonlinear elements. It is shown that near a Fano resonance, these structures may have a strong tunable, bistable, and switchable response and enable giant nonlinear effects. By using an effective medium theory and full wave simulations, it is proven that the nonlinear elements may allow the reflection and transmission coefficients to follow hysteresis loops, and to switch the metamaterial between “go” and “no-go” states similar to an ideal electromagnetic switch.
Analyse this! A cosmological constraint package for CMBEASY

We introduce a Markov chain Monte Carlo simulation and data analysis package that extends the Cmbeasy software. We have taken special care in implementing an adaptive step algorithm for the Markov chain Monte Carlo in order to improve convergence. Data analysis routines are provided which allow one to test models of the Universe against measurements of the cosmic microwave background, supernovae Ia and Large Scale Structure. We present constraints on cosmological parameters derived from these measurements for a ΛCDM cosmology and discuss the impact of the different observational data sets on the parameters. The package is publicly available as part of the Cmbeasy software at www.cmbeasy. org.