Miracle-dz/UniFAR-FTUs huggingface dataset:
AGB stars in the SMC: evolution and dust properties based on Spitzer observations

We study the population of asymptotic giant branch (AGB) stars in the Small Magellanic Cloud (SMC) by means of full evolutionary models of stars of mass 1Msun < M < 8Msun, evolved through the thermally pulsing phase. The models also account for dust production in the circumstellar envelope. We compare Spitzer infrared colours with results from theoretical modelling. We show that ~75% of the AGB population of the SMC is composed by scarcely obscured objects, mainly stars of mass M < 2.5Msun at various metallicity, formed between 700 Myr and 5 Gyr ago; ~ 70% of these sources are oxygen--rich stars, while ~ 30% are C-stars. The sample of the most obscured AGB stars, accounting for ~ 25% of the total sample, is composed almost entirely by carbon stars. The distribution in the colour-colour ([3.6]-[4.5], [5.8]-[8.0]) and colour-magnitude ([3.6]-[8.0], [8.0]) diagrams of these C-rich objects, with a large infrared emission, traces an obscuration sequence, according to the amount of carbonaceous dust in their surroundings. The overall population of C-rich AGB stars descends from 1.5-2Msun stars of metallicity Z=0.004, formed between 700 Myr and 2 Gyr ago, and from lower metallicity objects, of mass below 1.5Msun, 2-5 Gyr old. We also identify obscured oxygen-rich stars (M ~ 4-6Msun) experiencing hot bottom burning. The differences between the AGB populations of the SMC and LMC are also commented.
DEPENDENCE OF THE OPTICAL/ULTRAVIOLET VARIABILITY ON THE EMISSION-LINE PROPERTIES AND EDDINGTON RATIO IN ACTIVE GALACTIC NUCLEI

The dependence of the long-term optical/UV variability on the spectral and fundamental physical parameters for radio-quiet active galactic nuclei (AGNs) is investigated. The multi-epoch-repeated photometric scanning data in the Stripe-82 region of the Sloan Digital Sky Survey (SDSS) are exploited for two comparative AGN samples (mostly quasars) selected therein: a broad-line Seyfert 1 (BLS1) type sample and a narrow-line Seyfert 1 (NLS1) type AGN sample within redshifts 0.3–0.8. Their spectral parameters are derived from the SDSS spectroscopic data. It is found that on rest-frame timescales of several years the NLS1-type AGNs show systematically smaller variability compared to the BLS1-type AGNs. In fact, the variability amplitude is found to correlate, though only moderately, with the eigenvector 1 parameters, i.e., the smaller the Hβ linewidth, the weaker the [O iii] and the stronger the Fe ii emission, the smaller the variability amplitude. Moreover, an interesting inverse correlation is found between the variability and the Eddington ratio, which is perhaps more fundamental. The previously known dependence of the variability on luminosity is not significant, and the dependence on black hole mass—as claimed in recent papers and also present in our data—fades out when controlling for the Eddington ratio in the correlation analysis, though these may be partly due to the limited ranges of luminosity and black hole mass of our samples. Our result strongly supports that an accretion disk is likely to play a major role in producing the optical/UV variability.
Cosmology and astrophysics from relaxed galaxy clusters - II. Cosmological constraints

We present cosmological constraints from measurements of the gas mass fraction, $f_{gas}$, for massive, dynamically relaxed galaxy clusters. Our data set consists of Chandra observations of 40 such clusters, identified in a comprehensive search of the Chandra archive, as well as high-quality weak gravitational lensing data for a subset of these clusters. Incorporating a robust gravitational lensing calibration of the X-ray mass estimates, and restricting our measurements to the most self-similar and accurately measured regions of clusters, significantly reduces systematic uncertainties compared to previous work. Our data for the first time constrain the intrinsic scatter in $f_{gas}$, $(7.4\pm2.3)$% in a spherical shell at radii 0.8-1.2 $r_{2500}$, consistent with the expected variation in gas depletion and non-thermal pressure for relaxed clusters. From the lowest-redshift data in our sample we obtain a constraint on a combination of the Hubble parameter and cosmic baryon fraction, $h^{3/2}\Omega_b/\Omega_m=0.089\pm0.012$, that is insensitive to the nature of dark energy. Combined with standard priors on $h$ and $\Omega_b h^2$, this provides a tight constraint on the cosmic matter density, $\Omega_m=0.27\pm0.04$, which is similarly insensitive to dark energy. Using the entire cluster sample, extending to $z>1$, we obtain consistent results for $\Omega_m$ and interesting constraints on dark energy: $\Omega_\Lambda=0.65^{+0.17}_{-0.22}$ for non-flat $\Lambda$CDM models, and $w=-0.98\pm0.26$ for flat constant-$w$ models. Our results are both competitive and consistent with those from recent CMB, SNIa and BAO data. We present constraints on models of evolving dark energy from the combination of $f_{gas}$ data with these external data sets, and comment on the possibilities for improved $f_{gas}$ constraints using current and next-generation X-ray observatories and lensing data. (Abridged)
Image Spatial Resolution Importance on Burned Wetlands Monitoring in the Paraná River - Argentina

In Argentina, fires have always been present in the mainland ecosystems of the central-south region. However, the Paraná River wetland system has been going through a critical hydrological situation for a couple of years, which triggers many fire events that challenge the academic community as well as the local governments. Common low spatial resolutions remote sensing products seem to be unsuitable to monitor the processes associated with fire events in wetland environments. Thus, in this work we analyzed the use of vegetation indexes and surface temperature with fine spatial resolution images, such as Sentinel 2 and Landsat, to capture the variability of fire stages in the Paraná River wetlands. Our results suggest that Sentinel 2 and Landsat 8 and 9 are appropriate to monitor heterogeneous burned vegetation and its recovery.
Flexible Security and Privacy, System Architecture for IoT, in Healthcare

In recent years, the Internet of Things (IoT) technology is continuously being applied in the Healthcare domain because of the new services and capabilities it offers. Nevertheless, this technology has many vulnerabilities and network threats that service providers must first overcome before employing IoT-based smart health applications. Specifically, the data privacy, authentication and confidentiality of the system must be ensured because the IoT devices transmit personal health data and the smart health services are directly connected with the users’ wellbeing. Therefore, a complete and secure healthcare architecture based on IoT technology is needed. In this paper, a flexible security and privacy scheme is proposed. The design is based upon the SM4 block cipher and two innovative modes of operation, namely Counter with Cipher Block Chaining-Message Authentication Code (CCM) and Electronic Codebook (ECB), to enhance the flexibility and scalability of the system. The purpose of the architecture is to provide confidentiality to the IoT-based healthcare system and ensure the privacy and authenticity of the data transmitted. The performance results validate the security and hardware efficiency of the novel architecture compared to other related designs. Specifically, the decrease in hardware resources compared to AES-CCM designs is up to 96.7% with the increase in throughput compared to optimized SM4 systems being 71.3%. Overall, the proposed scheme innovatively implements established security primitives while considering the resource limitations and requirements of smart health services.
Mapping the three-dimensional multi-band extinction and diffuse interstellar bands in the Milky Way with LAMOST

Abstract With modern large scale spectroscopic surveys, such as the SDSS and LSS-GAC, Galactic astronomy has entered the era of millions of stellar spectra. Taking advantage of the huge spectroscopic database, we propose to use a “standard pair" technique to a) Estimate multi-band extinction towards sightlines of millions of stars; b) Detect and measure the diffuse interstellar bands in hundreds of thousands SDSS and LAMOST low-resolution spectra; c) Search for extremely faint emission line nebulae in the Galaxy; and d) Perform photometric calibration for wide field imaging surveys. In this contribution, we present some results of applying this technique to the SDSS data, and report preliminary results from the LAMOST data.
Interpreting the radio/X-ray correlation of black hole X-ray binaries based on the accretion–jet model

Two types of correlations between the radio and X-ray luminosities ($L_R$ and $L_X$) have been found in black hole X-ray binaries. For some sources, they follow the `original' type of correlation which is described by a single power-law. Later it was found that some other sources follow a different correlation consisting of three power-law branches, with each branch having different power-law indexes. In this work, we explain these two types of correlation under the coupled accretion--jet model. We attribute the difference between these two types of sources to the different value of viscosity parameter $\alpha$. One possible reason for different $\alpha$ is the different configuration of magnetic field in the accretion material coming from the companion stars. For the `single power-law' sources, their $\alpha$ is high; so their accretion is always in the mode of advection-dominated accretion flow (ADAF) for the whole range of X-ray luminosity. For those `hybrid power-law' sources, the value of $\alpha$ is small so their accretion mode changes from an ADAF to a luminous hot accretion flow, and eventually to two-phase accretion as the accretion rate increases. Because the dependence of radiative efficiency on the mass accretion rate is different for these three accretion modes, different power-law indexes in the $L_R--L_X$ correlation are expected. Constraints on the ratio of the mass loss rate into the jet and the mass accretion rate in the accretion flow are obtained, which can be tested in future by radiative magnetohydrodynamic numerical simulations of jet formation.
Evolution of Quasar Stochastic Variability along Its Main Sequence

We explore the evolution of the time variability (in the optical g-band and on timescales of weeks to years) of Sloan Digital Sky Survey Stripe 82 quasars along the quasar main sequence. A parent sample of 1004 quasars within 0.5 ≤ z ≤ 0.89 was used for our statistical studies; we then made subsamples from our parent sample: a subsample of 246 quasars with similar luminosities, and a subsample of 399 quasars with similar (i.e., the ratio of the equivalent width of Fe ii within 4435–4685 Å to that of Hβ). We find the variability amplitude decreases with luminosity (Lbol). The anticorrelation between the variability amplitude and is weak but statistically significant. The characteristic timescale, τ, correlates mostly with quasar luminosity; its dependence on is statistically insignificant. After controlling luminosity and , the high- and low-FWHM samples have similar structure functions. These results support the framework that is governed by Eddington ratio and the FWHM of Hβ is mostly determined by orientation. We then provide new empirical relations between variability parameters and quasar properties (i.e., luminosity and ). Our new relations are consistent with the scenario that quasar variability is driven by thermal fluctuations in the accretion disk; τ seems to correspond to the thermal timescale. From our new relations, we find that the short-term variability is mostly sensitive to Lbol. Based on this we propose that quasar short-term (a few months) variability might be a new type of “Standard Candle” and can be adopted to probe cosmology.
Large primordial trispectra in general single field inflation

We compute the large scalar four-point correlation functions in general single field inflation models, where the inflaton Lagrangian is an arbitrary function of the inflaton and its first derivative. We find that the leading order trispectra have four different shapes determined by three parameters. We study features in these shapes that can be used to distinguish among themselves, and between them and the trispectra of the local form. For the purpose of data analyses, we give two simple representative forms for these ``equilateral trispectra''. We also study the effects on the trispectra if the initial state of inflation deviates from the standard Bunch-Davies vacuum.
Continuous metal-insulator transition of the antiferromagnetic perovskite NaOsO3

Newly synthesized perovskite NaOsO 3 shows Curie-Weiss metallic nature at high temperature and suddenly goes into an antiferromagnetically insulating state at 410 K on cooling. specific heat at the low temperature limit is absent, indicating that the band gap fully opens. In situ observation in electron microscopy undetected any lattice anomalies in the vicinity of the transition temperature. It is most likely that the antiferromagnetic correlation plays an essential role of the gap opening. PACS:
A study of the near-infrared modulation at spin and orbital periods in the intermediate polar WX Pyx

We present near-infrared $J$ band photometric observations of the intermediate polar WX Pyx. The frequency analysis indicates the presence of a period at 1559.2 $\pm$ 0.2 seconds which is attributed to the spin period of the white dwarf. The spin period inferred from the infrared data closely matches that determined from X-ray and optical observations. WX Pyx is a system whose orbital period has not been measured directly and which is not too well constrained. From the IR observations, a likely peak at 5.30 $\pm$ 0.02 hour is seen in the power spectrum of the object. It is suggested that this corresponds to the orbital period of the system. In case this is indeed the true orbital period, some of the system physical parameters may be estimated. Our analysis indicates that the secondary star is of M2 spectral type and the distance to the object is 1.53 kpc. An upper limit of 30$^\circ$ for the angle of inclination of the system is suggested. The mass transfer rate and the magnetic moment of the white dwarf are estimated to be (0.95 - 1.6)$\times 10^{-9} M_\odot$ yr$^{-1}$ and (1.9 - 2.4)$ \times 10^{33}$ G cm$^{3}$ respectively.
NEAR-INFRARED LINE IDENTIFICATION IN TYPE Ia SUPERNOVAE DURING THE TRANSITIONAL PHASE

We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal Type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe ii and Co ii. In addition, we find that [Ni ii] fits the emission feature near 1.98 μm, suggesting that a substantial mass of 58Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density.
A MACHINE LEARNING APPROACH FOR DYNAMICAL MASS MEASUREMENTS OF GALAXY CLUSTERS

We present a modern machine learning (ML) approach for cluster dynamical mass measurements that is a factor-of-two improvement over using a conventional scaling relation. Different methods are tested against a mock cluster catalog constructed using halos with mass ≥ 10 14 M ⊙ h − 1 ? > from Multidark’s publicly available N-body MDPL halo catalog. In the conventional method, we use a standard M(σv) power-law scaling relation to infer cluster mass, M, from line of sight (LOS) galaxy velocity dispersion, σv. The resulting fractional mass error distribution is broad, with width Δ ϵ ≈ 0.87 ? > (68% scatter), and has extended high-error tails. The standard scaling relation can be simply enhanced by including higher-order moments of the LOS velocity distribution. Applying the kurtosis as a correction term to log ( &sgr; v ) ? > reduces the width of the error distribution to Δ ϵ ≈ 0.74 ? > (16% improvement). ML can be used to take full advantage of all the information in the velocity distribution. We employ the Support Distribution Machines (SDMs) algorithm that learns from distributions of data to predict single values. SDMs trained and tested on the distribution of LOS velocities yield Δ ϵ ≈ 0.46 ? > (47% improvement). Furthermore, the problematic tails of the mass error distribution are effectively eliminated. Decreasing cluster mass errors will improve measurements of the growth of structure and lead to tighter constraints on cosmological parameters.
THE MOLECULAR GAS IN LUMINOUS INFRARED GALAXIES. II. EXTREME PHYSICAL CONDITIONS AND THEIR EFFECTS ON THE Xco FACTOR

In this work, we conclude the analysis of our CO line survey of luminous infrared galaxies (LIRGs: LIR ≳ 1011 L☉) in the local universe (Paper I) by focusing on the influence of their average interstellar medium (ISM) properties on the total molecular gas mass estimates via the so-called Xco = M(H2)/Lco, 1–0 factor. One-phase radiative transfer models of the global CO spectral line energy distributions (SLEDs) yield an Xco distribution with 〈Xco〉 ∼ (0.6 ± 0.2) M☉ (K km s−1 pc2)−1 over a significant range of average gas densities, temperatures, and dynamic states. The latter emerges as the most important parameter in determining Xco, with unbound states yielding low values and self-gravitating states yielding the highest ones. Nevertheless, in many (U)LIRGs where available higher-J CO lines (J = 3–2, 4–3, and/or J = 6–5) or HCN line data from the literature allow a separate assessment of the gas mass at high densities (⩾104 cm−3) rather than a simple one-phase analysis, we find that near-Galactic Xco ∼ (3–6) M☉ (K km s−1 pc2)−1 values become possible. We further show that in the highly turbulent molecular gas in ULIRGs, a high-density component will be common and can be massive enough for its high Xco to dominate the average value for the entire galaxy. Using solely low-J CO lines to constrain Xco in such environments (as has been the practice up until now) may have thus resulted in systematic underestimates of molecular gas mass in ULIRGs, as such lines are dominated by a warm, diffuse, and unbound gas phase with low Xco but very little mass. Only well-sampled high-J CO SLEDs (J = 3–2 and higher) and/or multi-J observations of heavy rotor molecules (e.g., HCN) can circumvent such a bias, and the latter type of observations may have actually provided early evidence of it in local ULIRGs. The only way that the global Xco of such systems could be significantly lower than Galactic is if the average dynamic state of the dense gas is strongly gravitationally unbound. This is an unlikely possibility that must nevertheless be examined, with lines of rare isotopologues of high gas density tracers (e.g., H13CN, high-J 13CO lines) being very valuable in yielding (along with the lines of the main isotopes) such constraints. For less IR-luminous, disk-dominated systems, we find that the galaxy-averaged Xco deduced by one-phase models of global SLEDs can also underestimate the total molecular gas mass when much of it lies in an star-formation-quiescent phase extending beyond a central star-forming region. This is because such a phase (and its large Xco) remains inconspicuous in global CO SLEDs. Finally, detailed studies of a subsample of galaxies find ULIRGs with large amounts (∼109 M☉) of very warm (⩾100 K) and dense gas (≳105 cm−3), which could represent a serious challenge to photon-dominated regions as the main energy portals in the molecular ISM of such systems.
Highly sensitive electrospun SnO2-ZnO composite nanofibers for low concentration ethanol detection

The present work demonstrates the sub-ppm detection of ethanol using electrospun SnO2-ZnO composite nanofibers on interdigitated gold electrodes (IDGE). The fabricated sensor has shown excellent % response of 43.4 % at 0.5 ppm and 371 % at 100 ppm of ethanol. The sensor is appreciably selective towards ethanol and has shown fast response and recovery. The high % response of the sensor is attributed to the high specific surface area and low crystallite size of 55.43 nm. The adsorption reaction process at n-n heterojunction interface is used to explain the ethanol sensing mechanism of the composite. Further, XRD, XPS and FESEM analysis have been done to study the crystal structure, valence states and surface morphology of the SnO2-ZnO composite.
Sub-mm emission line deep fields: CO and [C II] luminosity functions out to z = 6

Now that Atacama Large (Sub)Millimeter Array is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J =1-0 out to CO J = 6-5 and [C II] at redshifts z= 0-6. We find that (1) our model correctly reproduces the CO and [C II] emission of low- and high-redshift galaxies and reproduces the available constraints on the CO luminosity function at z ≤ 2.75; (2) we find that the CO and [C II] luminosity functions of galaxies increase from z = 6 to z = 4, remain relatively constant till z = 1 and rapidly decrease towards z = 0. The galaxies that are brightest in CO and [C II] are found at z ˜ 2; (3) the CO J = 3-2 emission line is most favourable to study the CO luminosity and global H2 mass content of galaxies, because of its brightness and observability with currently available sub-mm and radio instruments; (4) the luminosity functions of high-J CO lines show stronger evolution than the luminosity functions of low-J CO lines; (5) our model barely reproduces the available constraints on the
Migration and kinematics in growing disc galaxies with thin and thick discs

We analyse disc heating and radial migration in N-body models of growing disc galaxies with thick and thin discs. Similar to thin-disc-only models, galaxies with appropriate non-axisymmetric structures reproduce observational constraints on radial disc heating in and migration to the Solar Neighbourhood (Snhd). The presence of thick discs can suppress non-axisymmetries and thus higher baryonic-to-dark matter fractions are required than in models that only have a thin disc. Models that are baryon-dominated to roughly the Solar radius R0 are favoured, in agreement with data for the Milky Way. For inside-out growing discs, today’s thick-disc stars at R0 are dominated by outwards migrators. Whether outwards migrators are vertically hotter than non-migrators depends on the radial gradient of the thick disc vertical velocity dispersion. There is an effective upper boundary in angular momentum that thick disc stars born in the centre of a galaxy can reach by migration, which explains the fading of the high [α/Fe] sequence outside R0. Our models compare well to Snhd kinematics from RAVE-TGAS. For such comparisons it is important to take into account the azimuthal variation of kinematics at R ∼ R0 and biases from survey selection functions. The vertical heating of thin disc stars by giant molecular clouds is only mildly affected by the presence of thick discs. Our models predict higher vertical velocity dispersions for the oldest stars than found in the Snhd age velocity dispersion relation, possibly because of measurement uncertainties or an underestimation of the number of old cold stars in our models.