Miracle-dz/UniFAR-FTUs huggingface dataset:
Modelling the cross-spectral variability of the black hole binary MAXI J1659-152 with propagating accretion rate fluctuations

The power spectrum of the X-ray fluctuations of accreting black holes often consists of two broad humps. We quantitatively investigate the hypothesis that the lower frequency hump originates from variability in a truncated thin accretion disc, propagating into a large scaleheight inner hot flow which, in turn, itself is the origin of the higher frequency hump. We extend the propagating mass accretion rate fluctuations model PROPFLUC to accommodate double-hump power spectra in this way. Furthermore, we extend the model to predict the cross-spectrum between two energy bands in addition to their power spectra, allowing us to constrain the model using the observed time lags, which in the model result from both propagation of fluctuations from the disc to the hot flow, and inside the hot flow. We jointly fit soft and hard power spectrum, and the cross-spectrum between the two bands using this model for five Swift X-ray Telescope observations of MAXI J1659-152. The new double-hump model provides a better fit to the data than the old single-hump model for most of our observations. The data show only a small phase lag associated with the low-frequency hump. We demonstrate quantitatively that this is consistent with the model. We compare the truncation radius measured from our fits with that measured purely by spectral fitting and find agreement within a factor of two. This analysis encompasses the first joint fits of stellar-mass black hole cross-spectra and power spectra with a single self-consistent physical model.
Broad-band spectroscopy of the transient X-ray binary pulsar KS 1947+300 during 2013 giant outburst: Detection of pulsating soft X-ray excess component

We present the results obtained from detailed timing and spectral studies of the Be/X-ray binary pulsar KS 1947+300 during its 2013 giant outburst. We used data from Suzaku observations of the pulsar at two epochs, i.e. on 2013 October 22 (close to the peak of the outburst) and 2013 November 22. X-ray pulsations at ∼18.81 s were clearly detected in the light curves obtained from both observations. Pulse periods estimated during the outburst showed that the pulsar was spinning up. The pulse profile was found to be single-peaked up to ∼10 keV beyond which a sharp peak followed by a dip-like feature appeared at hard X-rays. The dip-like feature has been observed up to ∼70 keV. The 1–110 keV broad-band spectroscopy of both observations revealed that the best-fit model was comprised of a partially absorbed Negative and Positive power law with EXponential cutoff (NPEX) continuum model along with a blackbody component for the soft X-ray excess and two Gaussian functions at 6.4 and 6.7 keV for emission lines. Both the lines were identified as emission from neutral and He-like iron atoms. To fit the spectra, we included the previously reported cyclotron absorption line at 12.2 keV. From the spin-up rate, the magnetic field of the pulsar was estimated to be ∼1.2×1012 G and found to be comparable to that obtained from the detection of the cyclotron absorption feature. Pulse-phase resolved spectroscopy revealed the pulsating nature of the soft X-ray excess component in phase with the continuum flux. This confirms that the accretion column and/or accretion stream are the most probable regions of the soft X-ray excess emission in KS1947+300. The presence of the pulsating soft X-ray excess in phase with continuum emission may be the possible reason for not observing the dip at soft X-rays.
Relaxation dynamics of the toric code in contact with a thermal reservoir: Finite-size scaling in a low-temperature regime

We present an analysis of the relaxation dynamics of finite-size topological qubits in contact with a thermal bath. Using a continuous-time Monte Carlo method, we explicitly compute the low-temperature nonequilibrium dynamics of the toric code on finite lattices. In contrast to the size-independent bound predicted for the toric code in the thermodynamic limit, we identify a low-temperature regime on finite lattices below a size-dependent crossover temperature with nontrivial finite-size and temperature scaling of the relaxation time. We demonstrate how this nontrivial finite-size scaling is governed by the scaling of topologically nontrivial two-dimensional classical random walks. The transition out of this low-temperature regime defines a dynamical finite-size crossover temperature that scales inversely with the log of the system size, in agreement with a crossover temperature defined from equilibrium properties. We find that both the finite-size and finite-temperature scaling are stronger in the low-temperature regime than above the crossover temperature. Since this finite-temperature scaling competes with the scaling of the robustness to unitary perturbations, this analysis may elucidate the scaling of memory lifetimes of possible physical realizations of topological qubits.
Ultrafast spin-polarization control of Dirac fermions in topological insulators

Topological insulators are promising materials for future spintronic applications due to the unique properties of their spin-polarized surface states. Using time-, spin-, and angle-resolved photoemission spectroscopy, the authors establish the utilization of photoexcited topological surface states as unique channels in which to drive fully controllable spin-polarized electrical currents on ultrafast time scales. Using circularly polarized femtosecond laser pulses of infrared light, the authors show that the dynamics of the generated currents exhibits two distinct timescales for the spin and charge degrees of freedom on the surface, and identify the underlying mechanisms giving rise to this behavior. Moreover, they find that the generated currents are completely reversible with the helicity of the circular-light polarization, paving the way for novel applications of topological insulators in spintronics at ultimate speeds.
Prospects of the detection of circumbinary planets with Kepler and CoRoT using the variations of eclipse timing

In close eclipsing binaries, measurements of the variations in binary's eclipse timing may be used to infer information about the existence of circumbinary objects. To determine the possibility of the detection of such variations with CoRoT and Kepler space telescopes, we have carried out an extensive study of the dynamics of a binary star system with a circumbinary planet, and calculated its eclipse timing variations (ETVs) for different values of the mass ratio and orbital elements of the binary and the perturbing body. Here, we present the results of our study and assess the detectability of the planet by comparing the resulting values of ETVs with the temporal sensitivity of CoRoT and Kepler. Results point to extended regions in the parameter space where the perturbation of a planet may be large enough to create measurable variations in the eclipse timing of the secondary star. Many of these variations point to potentially detectable ETVs and the possible inference of Jovian-type planets.
OPTICAL SPECTRAL PROPERTIES OF SWIFT BURST ALERT TELESCOPE HARD X-RAY-SELECTED ACTIVE GALACTIC NUCLEI SOURCES

The Swift Burst Alert Telescope survey of active galactic nuclei (AGNs) is providing an unprecedented view of local AGNs (〈z〉 ≈ 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a sample of 64 AGNs from the nine month survey, detected solely based on their 14–195 keV flux. Our analysis includes both archived spectra from the Sloan Digital Sky Survey and our own observations from the 2.1 m Kitt Peak National Observatory telescope. Among our results, we include line ratio classifications utilizing standard emission line diagnostic plots, [O iii] 5007 Å luminosities, and Hβ-derived black hole masses. As in our X-ray study, we find the type 2 sources to be less luminous (in [O iii] 5007 Å and 14–195 keV luminosities) with lower accretion rates than the type 1 sources. We find that the optically classified low-ionization narrow emission line regions, H ii/composite galaxies, and ambiguous sources have the lowest luminosities, while both broad-line and narrow-line Seyferts have similar luminosities. From a comparison of the hard X-ray (14–195 keV) and [O iii] luminosities, we find that both the observed and extinction-corrected [O iii] luminosities are weakly correlated with X-ray luminosity. In a study of the host galaxy properties from both continuum fits and measurements of the stellar absorption indices, we find that the hosts of the narrow-line sources have properties consistent with late-type galaxies.
Phonon-drag effect in FeGa3

The thermoelectric properties of single- and polycrystalline FeGa3 are systematically investigated over a wide temperature range. At low temperatures, below 20 K, previously not known pronounced peaks in the thermal conductivity (400-800 W K^-1m-1) with corresponding maxima in the thermopower (in the order of -16000 microV/K) were found in single crystalline samples. Measurements in single crystals along [100] and [001] directions indicate only a slight anisotropy in both the electrical and thermal transport. From susceptibility and heat capacity measurements, a structural or magnetic phase transition was excluded. Using density functional theory-based calculations, we have revisited the electronic structure of FeGa3 and compared the magnetic (including correlations) and non-magnetic electronic density of states. Thermopower at fixed carrier concentrations are calculated using semi-classical Boltzmann transport theory, and the calculated results match fairly with our experimental data and exclude the possibility of strong electronic correlations as an explanation for the low temperature enhancement. Eventually, after a careful review, we assign the peaks in the thermopower as a manifestation of the phonon-drag effect, which is supported by thermopower measurements in a magnetic field.
Localized surface plasmon resonance in SnS:Ag nano-composite films

Nano-composite films of Tin Sulfide (SnS) and silver fabricated by thermal evaporation showed two prominent peaks in the visible region of their extinction spectra. Theoretical modeling of the extinction spectra suggests that these two peaks (≈500 nm and ≈580 nm) correspond to the longitudinal mode and transverse mode surface plasmon resonance peaks arising from oblate silver nano-particles. Using grain size of silver and SnS obtained from structural and morphological characterizations of the samples and dielectric constants as per actuals, we have compared the experimental results with those from theory. The study shows that silver nano-particles efficiently scatters light and can be used for developing plasmonic based SnS solar cells with improved efficiencies.
Global structure of five-dimensional fuzzballs

We describe and study families of BPS microstate geometries, namely, smooth, horizonless asymptotically flat solutions to supergravity. We examine these solutions from the perspective of earlier attempts to find solitonic solutions in gravity and show how the microstate geometries circumvent the earlier ‘no-go’ theorems. In particular, we re-analyze the Smarr formula and show how it must be modified in the presence of non-trivial second homology. This, combined with the supergravity Chern–Simons terms, allows the existence of rich classes of BPS, globally hyperbolic, asymptotically flat, microstate geometries whose spatial topology is the connected sum of N copies of S2 × S2 with a ‘point at infinity’ removed. These solutions also exhibit ‘evanescent ergo-regions,’ that is, the non-space-like Killing vector guaranteed by supersymmetry is time-like everywhere except on time-like hypersurfaces (ergo-surfaces) where the Killing vector becomes null. As a by-product of our work, we are able to resolve the puzzle of why some regular soliton solutions violate the BPS bound: their spacetimes do not admit a spin structure.
A TALE OF DWARFS AND GIANTS: USING A z = 1.62 CLUSTER TO UNDERSTAND HOW THE RED SEQUENCE GREW OVER THE LAST 9.5 BILLION YEARS

We study the red sequence in a cluster of galaxies at z = 1.62 and follow its evolution over the intervening 9.5 Gyr to the present day. Using deep YJKs imaging with the HAWK-I instrument on the Very Large Telescope, we identify a tight red sequence and construct its rest-frame i-band luminosity function (LF). There is a marked deficit of faint red galaxies in the cluster that causes a turnover in the LF. We compare the red-sequence LF to that for clusters at z < 0.8, correcting the luminosities for passive evolution. The shape of the cluster red-sequence LF does not evolve between z = 1.62 and z = 0.6 but at z < 0.6 the faint population builds up significantly. Meanwhile, between z = 1.62 and 0.6 the inferred total light on the red sequence grows by a factor of ∼2 and the bright end of the LF becomes more populated. We construct a simple model for red-sequence evolution that grows the red sequence in total luminosity and matches the constant LF shape at z > 0.6. In this model the cluster accretes blue galaxies from the field whose star formation is quenched and who are subsequently allowed to merge. We find that three to four mergers among cluster galaxies during the 4 Gyr between z = 1.62 and z = 0.6 match the observed LF evolution between the two redshifts. The inferred merger rate is consistent with other studies of this cluster. Our result supports the picture that galaxy merging during the major growth phase of massive clusters is an important process in shaping the red-sequence population at all luminosities.
WEIGHING STARS: THE IDENTIFICATION OF AN EVOLVED BLUE STRAGGLER STAR IN THE GLOBULAR CLUSTER 47 TUCANAE

Globular clusters are known to host peculiar objects named blue straggler stars (BSSs), significantly heavier than the normal stellar population. While these stars can be easily identified during their core hydrogen-burning phase, they are photometrically indistinguishable from their low-mass sisters in advanced stages of the subsequent evolution. A clear-cut identification of these objects would require the direct measurement of the stellar mass. We used the detailed comparison between chemical abundances derived from neutral and from ionized spectral lines as a powerful stellar “weighing device” to measure stellar mass and to identify an evolved BSS in 47 Tucanae. In particular, high-resolution spectra of three bright stars, located slightly above the level of the “canonical” horizontal branch (HB) sequence in the color–magnitude diagram of 47 Tucanae, have been obtained with the UVES spectrograph. The measurements of iron and titanium abundances performed separately from neutral and ionized lines reveal that two targets have stellar parameters fully consistent with those expected for low-mass post-HB objects, while for the other target the elemental ionization balance is obtained only by assuming a mass of ∼ 1.4 M ⊙ ? > , which is significantly larger than the main sequence turn-off mass of the cluster ( ∼ 0.85 M ⊙ ? > ). The comparison with theoretical stellar tracks suggests that this is a BSS descendant possibly experiencing its core helium-burning phase. The large applicability of the proposed method to most of the globular clusters in our Galaxy opens the possibility to initiate systematic searches for evolved BSSs, thus giving access to still unexplored phases of their evolution.
Spiral galaxies rotation curves in the Horava - Lifshitz gravity theory

We focus on a modified version of Horava-Lifschitz theory and, in particular, we consider the impact of its weak-field static spherically symmetric limit on the galaxy dynamics. In a previous paper, we used the modified gravitational potential obtained in this theory to evaluate the Milky Way rotation curve using a spheroidal truncated power-law bulge and a double exponential disc as the only sources of the gravitational field and showed that the modified rotation curved is not in agreement with the data. Making a step forward, we here include also the contribution from a dark matter halo in order to see whether this helps fitting the rotation curve data. As a test case, we consider a sample of spiral galaxies with smooth baryon matter distribution and well measured circular velocity profiles. It turns out that, although a marginal agreement with the data can be found, this can only be obtained if the dark matter halo has an unrealistically small virial mass and incredibly large concentration. Such results can be interpreted as a strong evidence against the reliability of the gravitational potential obtained in the modified version of Horava-Lifschitz theory that we consider.
Unravelling young COPD and pre-COPD in the general population

Background Chronic obstructive pulmonary disease (COPD) is commonly diagnosed when the airflow limitation is well established and symptomatic. We aimed to identify individuals at risk of developing COPD according to the concept of pre-COPD and compare their clinical characteristics with 1) those who have developed the disease at a young age, and 2) the overall population with and without COPD. Methods The EPISCAN II study is a cross-sectional, population-based study that aims to investigate the prevalence of COPD in Spain in subjects ≥40 years of age. Pre-COPD was defined as the presence of emphysema >5% and/or bronchial thickening by computed chromatography (CT) scan and/or diffusing capacity of the lung for carbon monoxide (DLCO) <80% of predicted in subjects with respiratory symptoms and post-bronchodilator forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) >0.70. Young COPD was defined as FEV1/FVC <0.70 in a subject ≤50 years of age. Demographic and clinical characteristics were compared among pre-COPD, young COPD and the overall population with and without COPD. Results Among the 1077 individuals with FEV1/FVC <0.70, 65 (6.0%) were ≤50 years of age. Among the 8015 individuals with FEV1/FVC >0.70, 350 underwent both DLCO testing and chest CT scanning. Of those, 78 (22.3%) subjects fulfilled the definition of pre-COPD. Subjects with pre-COPD were older, predominantly women, less frequently active or ex-smokers, with less frequent previous diagnosis of asthma but with higher symptomatic burden than those with young COPD. Conclusions 22.3% of the studied population was at risk of developing COPD, with similar symptomatic and structural changes to those with well-established disease without airflow obstruction. This COPD at-risk population is different from those that develop COPD at a young age. Subjects fulfilling the definition of pre-COPD show similar symptomatic and structural changes to those with well-stablished disease. The fixed ratio of FEV1/FVC definition for COPD is missing an important group of patients that have significant disease. https://bit.ly/3B3FUO3
RESOLVING THE CO SNOW LINE IN THE DISK AROUND HD 163296

We report Submillimeter Array observations of CO (J = 2–1, 3–2, and 6–5) and its isotopologues (13CO J = 2–1, C18O J = 2–1, and C17O J = 3–2) in the disk around the Herbig Ae star HD 163296 at ∼2″ (250 AU) resolution, and interpret these data in the framework of a model that constrains the radial and vertical location of the line emission regions. First, we develop a physically self-consistent accretion disk model with an exponentially tapered edge that matches the spectral energy distribution and spatially resolved millimeter dust continuum emission. Then, we refine the vertical structure of the model using wide range of excitation conditions sampled by the CO lines, in particular the rarely observed J = 6–5 transition. By fitting 13CO data in this structure, we further constrain the vertical distribution of CO to lie between a lower boundary below which CO freezes out onto dust grains (T ≲ 19 K) and an upper boundary above which CO can be photodissociated (the hydrogen column density from the disk surface is ≲ 1021 cm−2). The freezeout at 19 K leads to a significant drop in the gas-phase CO column density beyond a radius of ∼155 AU, a “CO snow line” that we directly resolve. By fitting the abundances of all CO isotopologues, we derive isotopic ratios of 12C/13C, 16O/18O, and 18O/17O that are consistent with quiescent interstellar gas-phase values. This detailed model of the HD 163296 disk demonstrates the potential of a staged, parametric technique for constructing unified gas and dust structure models and constraining the distribution of molecular abundances using resolved multi-transition, multi-isotope observations.
THE STRUCTURE OF MASSIVE QUIESCENT GALAXIES AT Z ∼ 3 IN THE CANDELS-COSMOS FIELD

In this Letter, we use a two-color (J − L) versus (V − J) selection criterion to search massive quiescent galaxy (QG) candidates at 2.5 ⩽ z ⩽ 4.0 in the CANDELS-COSMOS field. We construct an HF160W-selected catalog and complement it with public auxiliary data. We finally obtain 19 passive VJL-selected (hereafter pVJL) galaxies as the possible massive QG candidates at z ∼ 3 by several constrains. We find the sizes of our pVJL galaxies are on average three to four times smaller than those of local early-type galaxies (ETGs) with analogous stellar mass. The compact size of these z ∼ 3 galaxies can be modeled by assuming their formation at zform ∼ 4–6 according to the dissipative collapse of baryons. Up to z < 4, the mass-normalized size evolution can be described by re∝(1 + z)−1.0. Low Sérsic index and axis ratio, with median values n ∼1.5 and b/a ∼ 0.65, respectively, indicate that most of the pVJL galaxies are disk-dominated. Despite large uncertainty, the inner region of the median mass profile of our pVJL galaxies is similar to those of QGs at 0.5 < z < 2.5 and local ETGs. It indicates that local massive ETGs have been formed according to an inside-out scenario: the compact galaxies at high redshift make up the cores of local massive ETGs and then build up the outskirts according to dissipationless minor mergers.
BAYESIAN ESTIMATION OF THERMONUCLEAR REACTION RATES

The problem of estimating non-resonant astrophysical S-factors and thermonuclear reaction rates, based on measured nuclear cross sections, is of major interest for nuclear energy generation, neutrino physics, and element synthesis. Many different methods have been applied to this problem in the past, almost all of them based on traditional statistics. Bayesian methods, on the other hand, are now in widespread use in the physical sciences. In astronomy, for example, Bayesian statistics is applied to the observation of extrasolar planets, gravitational waves, and Type Ia supernovae. However, nuclear physics, in particular, has been slow to adopt Bayesian methods. We present astrophysical S-factors and reaction rates based on Bayesian statistics. We develop a framework that incorporates robust parameter estimation, systematic effects, and non-Gaussian uncertainties in a consistent manner. The method is applied to the reactions d(p,γ)3He, 3He(3He,2p)4He, and 3He(α,γ)7Be, important for deuterium burning, solar neutrinos, and Big Bang nucleosynthesis.