Miracle-dz/UniFAR-FTUs huggingface dataset:
Hyperfine interactions in silicon quantum dots

We present an all-electron calculation of the hyperfine parameters for conduction electrons in Si, showing that: (i) all parameters scale linearly with the spin density at a $^{29}$Si site; (ii) the isotropic term is over 30 times larger than the anisotropic part; (iii) conduction electron charge density at a Si nucleus is consistent with experimental estimates; (iv) Overhauser fields in natural Si quantum dots (QDs) are two orders of magnitude smaller than in GaAs QDs. This reinforces the outstanding performance of Si in keeping spin coherence and opens access to reliable quantitative information aiming at spintronic applications.
Spectral Lineshape Measurements with Shot-Noise Limited Accuracy

Spectroscopy has played the key role in revealing, and thereby understanding, the structure of atoms and molecules. A central drive in this field is the pursuit of higher precision and accuracy so that ever more subtle effects might be discovered. Here, we report on laser absorption spectroscopy that operates at the conventional quantum limit imposed by photon shot-noise. Furthermore, we achieve this limit without compromising the accuracy of the measurement. We demonstrate these properties by recording an absorption profile of cesium vapor at the 2 parts-per-million level. The extremely high signal-to-noise ratio allows us to directly observe the homogeneous lineshape component of the spectral profile, even while in the presence of Doppler broadening that is a factor of 100 times wider. We can do this because we can precisely measure the spectral profile at a frequency detuning more than 200 natural linewidths from the line center. We use the power of this tool to demonstrate direct measurements of a low-intensity optically-induced broadening process that is quite distinct from the well-known power broadening phenomenon.
A possible origin of the rapid variability of gamma-ray bursts due to convective energy transfer in hyperaccretion discs

We investigate the effects of the convection in the hyperaccretion disc around a stellar-mass black hole, which is considered to be the central engine of gamma-ray bursts (GRBs), with simple analytical calculations. If the convective energy transfer in the vertical direction becomes efficient compared with the inward advective energy transport, the hyperaccretion disc is expected to be hotter and the neutrino emission due to the electron–positron annihilation becomes the most efficient cooling process. We find that the sequence of the thermal equilibrium solutions for the convective hyperaccretion disc would have a viscously unstable branch, especially when the viscosity parameter is relatively small (α≲ 0.01). This means that the sporadical mass accretion on to a black hole would occur in this disc. We propose that this process can be the origin of the highly variable light curves observed in the prompt emissions of GRBs.
On the driver of relativistic effect strength in Seyfert galaxies

Context. Spectroscopy of X-ray emission lines emitted from accretion discs around supermassive black holes is one of the most powerful probes of the accretion flow physics and geometry, while also providing in principle observational constraints on the black hole spin. Previous studies have suggested that relativistically broadened line profiles are fairly common in nearby unobscured Seyfert galaxies. Their strength, as parametrised by the equivalent width (EW) against the total underlying continuum, spans a range of almost two orders of magnitude. Aims. We attempt to determine the ultimate physical driver of the strength of this relativistic reprocessing feature. Methods. We first extend the hard X-ray flux-limited sample of Seyfert galaxies studied so far in the framework of the FERO (Finding Extreme Relativistic Objects) project to obscured objects up to a column density NH = 6 × 10 23 cm −2 . We verify that none of the line properties depends on the AGN optical classification, as expected from the Seyfert unification scenarios. There is also no correlation between the accretion disc inclination, as derived from formal fits of the line profiles, and the optical type or host galaxy aspect angle, suggesting that the innermost regions of the accretion disc and the host galaxy plane are not aligned. We use this extended sample to study the dependence of the EW on various observables, and compare it with the predictions of Monte Carlo accretion-disc reprocessing simulation. Results. The behaviour of the EW as a function of disc inclination, shape of the intrinsic power-law nuclear continuum, or iron abundance does not agree with the simulation predictions. Our observational data are not sensitive enough to the detailed ionisation state of the line-emitting disc. However, the lack of dependence of the line EW on either the luminosity or the rest-frame centroid energy rules out disc ionisation playing an important role on the EW dynamical range in Seyferts. Conclusions. The dynamical range of the relativistically broadened Kα iron line EW in nearby Seyferts appears to be mainly determined by the properties of the innermost accretion flow. We discuss several mechanisms (disc ionisation, disc truncation, and aberration due to a mildly relativistic outflowing corona) that can explain this. We stress that the above results represent neither a falsification or proof of the relativistically blurring scenario. Observational data still do not contradict scenarios invoking different mechanisms for the spectral complexity around the iron line, most notably the “partial covering” absorption scenario.
ASASSN-15jd: WZ Sge-type star with intermediate superoutburst between single and double ones

We present optical photometry of a WZ Sge-type dwarf nova (DN), ASASSN-15jd. Its light curve showed a small dip in the middle of the superoutburst in 2015 for the first time among WZ Sge-type DNe. The unusual light curve implies a delay in the growth of the 3:1 resonance tidal instability. Also, the light curve is similar to those of other two WZ Sge-type stars, SSS J122221.7$-$311523 and OT J184228.1$+$483742, which are believed to be the best candidates for a period bouncer on the basis of their small values of the mass ratio ($q \equiv M_{2}/M_{1}$). Additionally, the small mean superhump amplitude ($<$ 0.1 mag) and the long duration of no ordinary superhumps at the early stage of the superoutburst are common to the best candidates for a period bouncer. The average superhump period was $P_{\rm sh}$ = 0.0649810(78) d and no early superhumps were detected. Although we could not estimate the mass ratio of ASASSN-15jd with high accuracy, this object is expected to be a candidate for a period bouncer, a binary accounting for the missing population of post-period minimum cataclysmic variables, based on the above characteristics.
Phosphorus lability in a subtropical Acrisol under long-term integrated crop-livestock system: impacts of grazing management and cropping system

: Studies on lability of soil phosphorus (P) under integrated crop-livestock systems (ICLS) are still scarce, especially for deep soil layers (more than 0.20 m depth) and different managements in the crop and livestock phase. Distinct management in these phases may lead to a different distribution of soil P pools according to its lability (labile, moderately labile, less labile and residual) and, consequently, the P availability for plant nutrition. This study aimed to determine the soil P pools, by P fractionation and its distribution in lability classes. In a long-term ICLS experiment of grain and sheep production established in 2003, in Southern Brazil, we sampled in 2017 the 0.00-0.05, 0.05-0.10, 0.10-0.20, 0.20-0.26, 0.26-0.30 and 0.30-0.40 m layers of a Red Dystrophic Acrisol ( Argissolo Vermelho distrófico ) under two cropping systems in the summer (soybean/corn rotation and soybean/soybean succession), two grazing intensities (moderate and low) and two methods (continuous and rotational) in winter. Fractionation of P consisted of sequential extractions with anionic exchange resin, NaHCO 3 0.5 mol L -1 , NaOH 0.1 mol L -1 , HCl 1 mol L -1 , and NaOH 0.5 mol L -1 . The fractions were grouped in four different pools: labile, moderated labile, less labile and residual P. The soybean/soybean succession increased the labile pool of soil P in the 0.00-0.10 m layer compared to the soybean/corn rotation, regardless of the management of the livestock phase. Meanwhile, the management of the livestock phase also influenced soil P lability, regardless of the management of the crop phase. Low grazing intensity increased the levels of labile soil P in the 0.00-0.05 m layer, in comparison with the moderate grazing intensity and regardless of the grazing method. Grazing methods did not impact the soil P lability or content. The greater soil P availability in the soybean/soybean succession can be attributed to the higher quality (low carbon/nitrogen ratio) of the residue, while in the low grazing intensity to the higher forage dry matter production. Such management benefits nutrient cycling and consequently the P availability to the plants, being important to decrease production costs with the reduction and/or greater use efficiency of phosphate fertilizers.
PRECISE STRONG LENSING MASS MODELING OF FOUR HUBBLE FRONTIER FIELD CLUSTERS AND A SAMPLE OF MAGNIFIED HIGH-REDSHIFT GALAXIES

We conduct precise strong lensing mass modeling of four Hubble Frontier Field (HFF) clusters, Abell 2744, MACS J0416.1−2403, MACS J0717.5+3745, and MACS J1149.6+2223, for which HFF imaging observations are completed. We construct a refined sample of more than 100 multiple images for each cluster by taking advantage of the full-depth HFF images, and conduct mass modeling using the glafic software, which assumes simply parametrized mass distributions. Our mass modeling also exploits a magnification constraint from the lensed SN Ia HFF14Tom for Abell 2744 and positional constraints from the multiple images S1–S4 of the lensed supernova SN Refsdal for MACS J1149.6+2223. We find that our best-fitting mass models reproduce the observed image positions with rms errors of ∼0. ″4, which are smaller than rms errors in previous mass modeling that adopted similar numbers of multiple images. Our model predicts a new image of SN Refsdal with a relative time delay and magnification that are fully consistent with a recent detection of reappearance. We then construct catalogs of z ∼ 6–9 dropout galaxies behind the four clusters and estimate magnification factors for these dropout galaxies with our best-fitting mass models. The dropout sample from the four cluster fields contains ∼120 galaxies at z ≳ 6, about 20 of which are predicted to be magnified by a factor of more than 10. Some of the high-redshift galaxies detected in the HFF have lensing-corrected magnitudes of MUV ∼ −15 to −14. Our analysis demonstrates that the HFF data indeed offer an ideal opportunity to study faint high-redshift galaxies. All lensing maps produced from our mass modeling will be made available on the Space Telescope Science Institute website (https://archive.stsci.edu/prepds/frontier/lensmodels/).
Kuranishi spaces as a 2-category

This is a survey of the author's in-progress book arXiv:1409.6908. 'Kuranishi spaces' were introduced in the work of Fukaya, Oh, Ohta and Ono in symplectic geometry (see e.g. arXiv:1503.07631), as the geometric structure on moduli spaces of $J$-holomorphic curves. We propose a new definition of Kuranishi space, which has the nice property that they form a 2-category $\bf Kur$. Thus the homotopy category Ho$({\bf Kur})$ is an ordinary category of Kuranishi spaces. Any Fukaya-Oh-Ohta-Ono (FOOO) Kuranishi space $\bf X$ can be made into a compact Kuranishi space $\bf X'$ uniquely up to equivalence in $\bf Kur$ (that is, up to isomorphism in Ho$({\bf Kur})$), and conversely any compact Kuranishi space $\bf X'$ comes from some (nonunique) FOOO Kuranishi space $\bf X$. So FOOO Kuranishi spaces are equivalent to ours at one level, but our definition has better categorical properties. The same holds for McDuff and Wehrheim's 'Kuranishi atlases' in arXiv:1508.01556. Using results of Yang on polyfolds and Kuranishi spaces surveyed in arXiv:1510.06849, a compact topological space $X$ with a 'polyfold Fredholm structure' in the sense of Hofer, Wysocki and Zehnder (see e.g. arXiv:1407.3185) can be made into a Kuranishi space $\bf X$ uniquely up to equivalence in $\bf Kur$. Our Kuranishi spaces are based on the author's theory of Derived Differential Geometry (see e.g. arXiv:1206.4207), the study of classes of derived manifolds and orbifolds that we call 'd-manifolds' and 'd-orbifolds'. There is an equivalence of 2-categories ${\bf Kur}\simeq{\bf dOrb}$, where $\bf dOrb$ is the 2-category of d-orbifolds. So Kuranishi spaces are really a form of derived orbifold. We discuss the differential geometry of Kuranishi spaces, and the author's programme for applying these ideas in symplectic geometry.
The tidal tails of the ultrafaint globular cluster Palomar 1

Using the optimal filter technique applied to Sloan Digital Sky Survey photometry, we have found extended tails stretching about 1° (or several tens of half-light radii) from either side of the ultrafaint globular cluster Palomar 1. The tails contain roughly as many stars as does the cluster itself. Using deeper Hubble Space Telescope data, we see that the isophotes twist in a characteristic S-shape on moving outwards from the cluster centre to the tails. We argue that the main mechanism forming the tails may be relaxation-driven evaporation and that Pal 1 may have been accreted from a now disrupted dwarf galaxy ∼ 500 Myr ago.
Conductance oscillations in quantum point contacts of InAs/GaSb heterostructures

We study quantum point contacts in two-dimensional topological insulators by means of quantum transport simulations for InAs/GaSb heterostructures and HgTe/(Hg,Cd)Te quantum wells. In InAs/GaSb, the density of edge states shows an oscillatory decay as a function of the distance to the edge. This is in contrast to the behavior of the edge states in HgTe quantum wells, which decay into the bulk in a simple exponential manner. The difference between the two materials is brought about by spatial separation of electrons and holes in InAs/GaSb, which affects the magnitudes of the parameters describing the particle-hole asymmetry and the strength of intersubband coupling within the Bernevig-Hughes-Zhang model. We show that the character of the wave function decay impacts directly the dependence of the point contact conductance on the constriction width and the Fermi energy, which can be verified experimentally and serve to determine accurately the values of relevant parameters. In the case of InAs/GaSb heterostructures the conductance magnitude oscillates as a function of the constriction width following the oscillations of the edge state penetration, whereas in HgTe/(Hg,Cd)Te quantum wells a single switching from transmitting to reflecting contact is predicted.
Nucleosynthesis in the first massive stars

The nucleosynthesis in the first massive stars may be constrained by observing the surface composition of long-lived very iron-poor stars born around 10 billion years ago from material enriched by their ejecta. Many interesting clues on physical processes having occurred in the first stars can be obtained based on nuclear aspects. First, in these first massive stars, mixing must have occurred between the H-burning and the He-burning zone during their nuclear lifetimes; Second, only the outer layers of these massive stars have enriched the material from which the very iron-poor stars, observed today in the halo of the MilkyWay, have formed. These two basic requirements can be obtained by rotating stellar models at very low metallicity. In the present paper, we discuss the arguments supporting this view and illustrate the sensitivity of the results concerning the [Mg/Al] ratio on the rate of the reaction 23Na(p,γ)24Mg.
Black holes die hard: Can one spin up a black hole past extremality?

A possible process to destroy a black hole consists on throwing point particles with sufficiently large angular momentum into the black hole. In the case of Kerr black holes, it was shown by Wald that particles with dangerously large angular momentum are simply not captured by the hole, and thus the event horizon is not destroyed. Here, we reconsider this gedanken experiment for a variety of black hole geometries, from black holes in higher dimensions to black rings. We show that this particular way of destroying a black hole does not succeed and that cosmic censorship is preserved.
SHORT-TERM VARIABILITY OF X-RAYS FROM ACCRETING NEUTRON STAR VELA X-1. I. SUZAKU OBSERVATIONS

We have analyzed the time variability of the wide-band X-ray spectrum of Vela X-1, the brightest wind-fed accreting neutron star, on a short timescale of 2 ks by using Suzaku observations with an exposure of 100 ks. During the observation, the object showed strong variability, including several flares and so-called “low states,” in which the X-ray luminosity decreases by an order of magnitude. Although the spectral hardness increases with the X-ray luminosity, the majority of the recorded flares do not show any significant changes in circumstellar absorption. However, a sign of heavy absorption was registered immediately before one short flare that showed a significant spectral hardening. In the low states, the flux level is modulated with the pulsar spin period, indicating that even at this state the accretion flow reaches the close proximity of the neutron star. Phenomenologically, the broadband X-ray spectra, which are integrated over the entire spin phase, are well represented by the “NPEX” function (a combination of negative and positive power laws with an exponential cutoff by a common folding energy) with a cyclotron resonance scattering feature at 50 keV. Fitting of the data allowed us to infer a correlation between the photon index and X-ray luminosity. Finally, the circumstellar absorption shows a gradual increase in the orbital phase interval 0.25–0.3, which can be interpreted as an impact of a bow shock imposed by the motion of the compact object in the supersonic stellar wind.
Light scattering by ultracold atoms in an optical lattice

We investigate theoretically light scattering of photons by ultracold atoms in an optical lattice in the linear regime. A full quantum theory for the atom-photon interactions is developed as a function of the atomic state in the lattice along the Mott-insulator-superfluid phase transition, and the photonic-scattering cross section is evaluated as a function of the energy and of the direction of emission. The predictions of this theory are compared with the theoretical results of a recent work on Bragg scattering in time-of-flight measurements [A.M. Rey et al., Phys. Rev. A 72, 023407 (2005)]. We show that, when performing Bragg spectroscopy with light scattering, the photon recoil gives rise to an additional atomic site-to-site hopping, which can interfere with ordinary tunneling of matter waves and can significantly affect the photonic-scattering cross section.
Dark matter detection with hard X-ray telescopes

We analyse the impact of future hard X-ray observations on the search for indirect signatures of particle dark matter in large extragalactic systems such as nearby clusters or groups of galaxies. We argue that the hard X-ray energy band falls squarely at the peak of the inverse-Compton emission from electrons and positrons produced by dark matter annihilation or decay for a large class of dark matter models. Specifically, the most promising are low-mass models with a hard electron–positron annihilation final state spectrum and intermediate-mass models with a soft electron–positron spectrum. We find that constraints on dark matter models similar to the current constraints from the Fermi Gamma-ray Space Telescope will be close to the sensitivity limit of the near-term hard X-ray telescopes Nuclear Spectroscopic Telescope Array (NuSTAR) and Astro-H for relatively long observations. An instrument like the Wide Field Imager proposed for Advanced Telescope for High ENergy Astrophysics (ATHENA) would instead give a significant gain in sensitivity to dark matter if placed in a low background orbit similar to NuSTAR’s; however, given the higher expected background level for ATHENA’s proposed orbit at L2, its sensitivity will be similar to that of NuSTAR.
A N=2 extension of the Hirota bilinear formalism and the supersymmetric KdV equation

We present a bilinear Hirota representation of the N=2 supersymmetric extension of the Korteweg-de Vries equation. This representation is deduced using binary Bell polynomials, hierarchies and fermionic limits. We, also, propose a new approach for the generalisation of the Hirota bilinear formalism in the N=2 supersymmetric context.
ADM analysis and massive gravity

This is a contribution to the Proceedings of the 7th Mathematical Physics Meeting: Summer School and Conference on Modern Mathematical Physics, held in Belgrade 09 – 19 September 2012. We give an easily accessible introduction to the ADM decomposition of the curvature components. After that we review the basic problems associated with attempts of constructing a viable massive gravity theory. And finally, we present the metric formulations of ghost-free massive gravity models, and comment on existence problem of the matrix square root.
Polarons and dressed molecules near narrow Feshbach resonances

The properties of impurities immersed in a large Fermi sea are naturally described in terms of dressed quasiparticles: attractive and repulsive polarons, and dressed molecules. Motivated by recent experiments on narrow Feshbach resonances, we analyze here how the quasiparticle properties are affected by a non-zero resonance range. We find two interesting analytic results. For large range, the ground-state energy close to resonance is shown to become perturbative in the inverse range. In the limit of broad resonance instead, we provide a new Tan's relation linking the impurity ground-state energy E↓ to the number of atoms in its dressing cloud ΔN. As a corollary, at unitarity one finds ΔN=−E↓/ϵF, with ϵF the Fermi energy of the bath.
SPATIAL CORRELATION BETWEEN DUST AND Hα EMISSION IN DWARF IRREGULAR GALAXIES

Using a sample of dwarf irregular galaxies selected from the ALFALFA blind H i-survey and observed using the VIMOS IFU, we investigate the relationship between Hα emission and Balmer optical depth ( ). We find a positive correlation between Hα luminosity surface density and Balmer optical depth in 8 of 11 at ≥0. 8σ significance (6 of 11 at ≥1.0σ) galaxies. Our spaxels have physical scales ranging from 30 to 80 pc, demonstrating that the correlation between these two variables continues to hold down to spatial scales as low as 30 pc. Using the Spearman’s rank correlation coefficient to test for correlation between and in all the galaxies combined, we find , indicating a positive correlation at 4σ significance. Our low stellar-mass galaxy results are in agreement with observations of emission line regions in larger spiral galaxies, indicating that this relationship is independent of the size of the galaxy hosting the emission line region. The positive correlation between Hα luminosity and Balmer optical depth within spaxels is consistent with the hypothesis that young star-forming regions are surrounded by dusty birth-clouds.