Miracle-dz/UniFAR-FTUs huggingface dataset:
SUB-THz RADIATION MECHANISMS IN SOLAR FLARES

Observations in the sub-THz range of large solar flares have revealed a mysterious spectral component increasing with frequency and hence distinct from the microwave component commonly accepted to be produced by gyrosynchrotron (GS) emission from accelerated electrons. Evidently, having a distinct sub-THz component requires either a distinct emission mechanism (compared to the GS one), or different properties of electrons and location, or both. We find, however, that the list of possible emission mechanisms is incomplete. This Letter proposes a more complete list of emission mechanisms, capable of producing a sub-THz component, both well known and new in this context, and calculates a representative set of their spectra produced by (1) free–free emission, (2) GS emission, (3) synchrotron emission from relativistic positrons/electrons, (4) diffusive radiation, and (5) Cherenkov emission. We discuss the possible role of the mechanisms in forming the sub-THz emission and emphasize their diagnostics potential for flares.
Suzaku and XMM-Newton observations of diffuse X-ray emission from the eastern tip region of the Carina Nebula

The eastern tip region of the Carina Nebula was observed with the Suzaku XIS for 77 ks to conduct a highprecision spectral study of extended X-ray emission. XMM-Newton EPIC data of this region were also utilized to detect point sources. The XIS detected strong extended X-ray emission from the entire field-of-view with a 0.2–5 keV flux of 0.7–4 10 14 erg s 1 arcmin . The emission has a blob-like structure that coincides with an ionized gas filament observed in mid-infrared images. Contributions of astrophysical backgrounds and the detected point sources were insignificant. Thus the emission is diffuse in nature. The X-ray spectrum of the diffuse emission was represented by a two-temperature plasma model with temperatures of 0.3 and 0.6 keV and an absorption column density of 2 10 cm . The X-ray emission showed normal nitrogen-to-oxygen abundance ratios and a high ironto-oxygen abundance ratio. The spectrally deduced parameters, such as temperatures and column densities, are common to the diffuse X-ray emission near Car. Thus, the diffuse X-ray emission in these two fields may have the same origin. The spectral fitting results are discussed to constrain the origin in the context of stellar winds and supernovae.
Determining the outcome of cosmic bubble collisions in full General Relativity

Cosmic bubble collisions provide an important possible observational window on the dynamics of eternal inflation. In eternal inflation, our observable universe is contained in one of many bubbles formed from an inflating metastable vacuum. The collision between bubbles can leave a detectable imprint on the cosmic microwave background radiation. Although phenomenological models of the observational signature have been proposed, to make the theory fully predictive one must determine the bubble collision spacetime, and thus the cosmological observables, from a scalar field theory giving rise to eternal inflation. Because of the intrinsically non-linear nature of the bubbles and their collision, this requires a numerical treatment incorporating General Relativity. In this paper, we present results from numerical simulations of bubble collisions in full General Relativity. These simulations allow us to accurately determine the outcome of bubble collisions, and examine their effect on the cosmology inside a bubble universe. We confirm the validity of a number of approximations used in previous analytic work, and identify qualitatively new features of bubble collision spacetimes. Both vacuum bubbles and bubbles containing a realistic inflationary cosmology are studied. We identify the constraints on the scalar field potential that must be satisfied in order to obtain collisions that are consistent with our observed cosmology, yet leave detectable signatures.
Spectroscopy of diagnostically-important magnetic-dipole lines in highly-charged 3d n ions of tungsten

An electron beam ion trap (EBIT) is used to measure extreme ultraviolet spectra between 10 nm and 25 nm from highly-charged ions of tungsten with an open 3d shell (W XLVIII through W LVI). We found that almost all strong lines are due to the forbidden magnetic-dipole (M1) transitions within 3d n ground configurations. A total of 37 spectral lines are identified for the first time using detailed collisional-radiative (CR) modeling of the EBIT spectra. A new level-merging scheme for compactification of rate equations is described. The CR simulations for Maxwellian plasmas show that several line ratios involving these M1 lines can be used to reliably diagnose temperature and density in hot fusion devices.
Effect of a Break in Flying on the Piloting Precision in Airline Pilots

Global air transport was experiencing a steady growth for decades despite various economic or political crises. However, the worldwide spread of Covid-19 and its associated travel restrictions led to an unprecedented 60 % drop in global air traffic volume according to the International Civil Aviation Organization (ICAO). This has had a dramatic impact on airline companies and their pilots who were suddenly unable to practice their profession. In order to return to service, they had to go through a simulator scenario aimed at restoring crucial pilot competencies. The following paper describes an experiment conducted with the goal to verify whether a simulator scenario proposed by IATA and adopted by airline companies can restore such competencies. The tailored experiment scenario involved specific flight maneuvers and precision approaches together with theoretical knowledge test. It was completed on a flight simulator with 34 pilots holding a valid type rating for Boeing 737NG. One of the results of the experiment show that the accuracy of a pilot's manual flight may not always correspond with the workload they are subjectively experiencing.
MIKiS: The Multi-instrument Kinematic Survey of Galactic Globular Clusters. I. Velocity Dispersion Profiles and Rotation Signals of 11 Globular Clusters

We present the first results of the Multi-Instrument Kinematic Survey of Galactic Globular Clusters (GGCs), a project aimed at exploring the internal kinematics of a representative sample of GGCs from the radial velocity of individual stars, covering the entire radial extension of each system. This is achieved by exploiting the formidable combination of multi-object and integral field unit spectroscopic facilities of the ESO Very Large Telescope. As a first step, here we discuss the results obtained for 11 clusters from high and medium resolution spectra acquired through a combination of FLAMES and KMOS observations. We provide the first kinematical characterization of NGC 1261 and NGC 6496. In all the surveyed systems, the velocity dispersion profile declines at increasing radii, in agreement with the expectation from the King model that best fits the density/luminosity profile. In the majority of the surveyed systems, we find evidence of rotation within a few half-mass radii from the center. These results are in general overall agreement with the predictions of recent theoretical studies, suggesting that the detected signals could be the relic of significant internal rotation set at the epoch of the cluster’s formation.
Exploring the long-term variability and evolutionary stage of the interacting binary DQ Velorum

Aims. In order to better understand the double periodic variable (DPV) phenomenon, we analyse a series of optical spectra of the DPV system DQ Velorum during much of its long-term cycle. In addition, we investigate the evolutionary history of DQ Vel using theoretical evolutionary models to obtain the best representation for the current observed stellar and orbital parameters of the binary. We investigate the evolution of DQ Vel through theoretical evolutionary models to estimate the age and the mass transfer rate which are then compared with those of its twin V393 Scorpii. Methods. We subtracted the donor star contribution from the composite spectra of DQ Vel using a synthetic spectrum as a donor template. Donor-subtracted spectra covering around 60% of the long-term cycle allowed us to investigate time-modulated spectral variations of the gainer star plus the disc. We used Gaussian fits to measure the equivalent widths (EWs) of Balmer and helium lines in the separated spectra during the long-term cycle and thus analyse EW variabilities. We compared the observed stellar parameters of the system with a grid of theoretical evolutionary tracks computed under a conservative and a non-conservative evolution regime. Results. We have found that the EW of Balmer and helium lines in the donor-subtracted spectra are modulated with the long-term cycle. We observe a strengthening in the EWs in all analysed spectral features at the minimum of the long-term cycle which might be related to an extra line emission during the maximum of the long-term variability. Difference spectra obtained at the secondary eclipse support this scenario. We have found that a non-conservative evolutionary model where DQ Vel has lost mass at some stage of its binary history, is a better representation of the current observed properties of the system. The best evolutionary model suggests that DQ Vel has an age of 7.40 × 10 7 yr and is currently in a low mass transfer rate (−9.8 × 10 −9 M� /yr) stage, after a mass transfer burst episode. Comparing the evolutionary stages of DQ Vel and V393 Sco we observed that the former is an older system with a lower mass transfer rate. This might explain the differences observed in the physical parameters of their accretion discs.
Precise analytic treatment of Kerr and Kerr-(anti) de Sitter black holes as gravitational lenses

The null geodesic equations that describe the motion of photons in Kerr spacetime are solved exactly in the presence of the cosmological constant Λ. The exact solution for the deflection angle for generic light orbits (i.e. non-polar, non-equatorial) is calculated in terms of the generalized hypergeometric functions of Appell and Lauricella. We then consider the more involved issue in which the black hole acts as a ‘gravitational lens’. The constructed Kerr black hole gravitational lens geometry consists of an observer and a source located far away and placed at arbitrary inclination with respect to the black hole's equatorial plane. The resulting lens equations are solved elegantly in terms of Appell–Lauricella hypergeometric functions and the Weierstraß elliptic function. We then, systematically, apply our closed form solutions for calculating the image and source positions of generic photon orbits that solve the lens equations and reach an observer located at various values of the polar angle for various values of the Kerr parameter and the first integrals of motion. In this framework, the magnification factors for generic orbits are calculated in closed analytic form for the first time. The exercise is repeated with the appropriate modifications for the case of a non-zero cosmological constant.
Light curves of the latest FUor: Indication of a close binary

We monitored the recent FUor 2MASS J06593158-0405277 (V960 Mon) since November 2009 at various observatories and multiple wavelengths. After the outburst by nearly 2.9 mag in r around September 2014 the brightness gently fades until April 2015 by nearly 1 mag in U and 0.5 mag in z. Thereafter the brightness at λ > 5000 A was constant until June 2015 while the shortest wavelengths (U, B) indicate a new rise, similar to that seen for the FUor V2493 Cyg (HBC722). Our near-infrared (NIR) monitoring between December 2014 and April 2015 shows a smaller outburst amplitude (∼2 mag) and a smaller (0.2–0.3 mag) post-outburst brightness decline. Optical and NIR color–magnitude diagrams indicate that the brightness decline is caused by growing extinction. The post-outburst light curves are modulated by an oscillating color-neutral pattern with a period of about 17 days and an amplitude declining from ∼0.08 mag in October 2014 to ∼0.04 mag in May 2015. The properties of the oscillating pattern lead us to suggest the presence of a close binary with eccentric orbit.
STAR FORMATION BIMODALITY IN EARLY-TYPE GALAXIES

We compute the properties of a sample of 221 local, early-type galaxies with a spectral energy distribution (SED) modeling software, CIGALEMC. Concentrating on the star-forming (SF) activity and dust contents, we derive parameters such as the specific star formation rate (sSFR), the dust luminosity, dust mass, and temperature. In our sample, 52% is composed of elliptical (E) galaxies and 48% of lenticular (S0) galaxies. We find a larger proportion of S0 galaxies among galaxies with a large sSFR and large specific dust emission. The stronger activity of S0 galaxies is confirmed by larger dust masses. We investigate the relative proportion of active galactic nuclei (AGNs) and SF galaxies in our sample using spectroscopic Sloan Digital Sky Survey data and near-infrared selection techniques, and find a larger proportion of AGN-dominated galaxies in the S0 sample than the E one. This could corroborate a scenario where blue galaxies evolve into red ellipticals by passing through an S0 AGN active period while quenching its star formation. Finally, we find a good agreement comparing our estimates with color indicators.
Simulating cosmic ray physics on a moving mesh

We discuss new methods to integrate the cosmic ray (CR) evolution equations coupled to magneto-hydrodynamics (MHD) on an unstructured moving mesh, as realised in the massively parallel AREPO code for cosmological simulations. We account for diffusive shock acceleration of CRs at resolved shocks and at supernova remnants in the interstellar medium (ISM), and follow the advective CR transport within the magnetised plasma, as well as anisotropic diffusive transport of CRs along the local magnetic field. CR losses are included in terms of Coulomb and hadronic interactions with the thermal plasma. We demonstrate the accuracy of our formalism for CR acceleration at shocks through simulations of plane-parallel shock tubes that are compared to newly derived exact solutions of the Riemann shock tube problem with CR acceleration. We find that the increased compressibility of the post-shock plasma due to the produced CRs decreases the shock speed. However, CR acceleration at spherically expanding blast waves does not significantly break the self-similarity of the Sedov-Taylor solution; the resulting modifications can be approximated by a suitably adjusted, but constant adiabatic index. In first applications of the new CR formalism to simulations of isolated galaxies and cosmic structure formation, we find that CRs add an important pressure component to the ISM that increases the vertical scale height of disk galaxies, and thus reduces the star formation rate. Strong external structure formation shocks inject CRs into the gas, but the relative pressure of this component decreases towards halo centres as adiabatic compression favours the thermal over the CR pressure.
Applications of Cosmological Perturbation Theory

Cosmological perturbation theory is crucial for our understanding of the universe. The linear theory has been well understood for some time, however developing and applying the theory beyond linear order is currently at the forefront of research in theoretical cosmology. This thesis studies the applications of perturbation theory to cosmology and, specifically, to the early universe. Starting with some background material introducing the well-tested 'standard model' of cosmology, we move on to develop the formalism for perturbation theory up to second order giving evolution equations for all types of scalar, vector and tensor perturbations, both in gauge dependent and gauge invariant form. We then move on to the main result of the thesis, showing that, at second order in perturbation theory, vorticity is sourced by a coupling term quadratic in energy density and entropy perturbations. This source term implies a qualitative difference to linear order. Thus, while at linear order vorticity decays with the expansion of the universe, the same is not true at higher orders. This will have important implications on future measurements of the polarisation of the Cosmic Microwave Background, and could give rise to the generation of a primordial seed magnetic field. Having derived this qualitative result, we then estimate the scale dependence and magnitude of the vorticity power spectrum, finding, for simple power law inputs a small, blue spectrum. The final part of this thesis concerns higher order perturbation theory, deriving, for the first time, the metric tensor, gauge transformation rules and governing equations for fully general third order perturbations. We close with a discussion of natural extensions to this work and other possible ideas for off-shooting projects in this continually growing field.
LARGE SIZE AND SLOW ROTATION OF THE TRANS-NEPTUNIAN OBJECT (225088) 2007 OR10 DISCOVERED FROM HERSCHEL AND K2 OBSERVATIONS

We present the first comprehensive thermal and rotational analysis of the second most distant trans-Neptunian object (TNOs) (225088) 2007 OR10. We combined optical light curves provided by the Kepler Space Telescope–K2 extended mission and thermal infrared data provided by the Herschel Space Observatory. We found that (225088) 2007 OR10 is likely to be larger and darker than derived by earlier studies: we obtained a diameter of d = 1535 − 225 + 75 km which places (225088) 2007 OR10 in the biggest top three TNOs. The corresponding visual geometric albedo is p V = 0.089 − 0.009 + 0.031 . The light-curve analysis revealed a slow rotation rate of Prot = 44.81 ± 0.37 hr, superseded by very few objects. The most likely light-curve solution is double-peaked with a slight asymmetry; however, we cannot safely rule out the possibility of having a rotation period of Prot = 22.40 ± 0.18 hr, which corresponds to a single-peaked solution. Due to the size and slow rotation, the shape of the object should be a MacLaurin ellipsoid, so the light variation should be caused by surface inhomogeneities. Its newly derived larger diameter also implies larger surface gravity and a more likely retention of volatiles—CH4, CO, and N2—on the surface.
ANGULAR MOMENTUM TRANSPORT IN SOLAR-TYPE STARS: TESTING THE TIMESCALE FOR CORE–ENVELOPE COUPLING

We critically examine the constraints on internal angular momentum transport which can be inferred from the spin-down of open cluster stars. The rotation distribution inferred from rotation velocities and periods is consistent for larger and more recent samples, but smaller samples of rotation periods appear biased toward shorter periods relative to vsin i studies. We therefore focus on whether the rotation period distributions observed in star forming regions can be evolved into the observed ones in the Pleiades, NGC 2516, M 34, M 35, M 37, and M 50 with plausible assumptions about star–disk coupling and angular momentum loss from magnetized solar-like winds. Solid-body (SB) models are consistent with the data for low-mass fully convective stars but highly inconsistent for higher mass stars where the surface convection zone can decouple for angular momentum purposes from the radiative interior. The Tayler–Spruit magnetic angular momentum transport mechanism, commonly employed in models of high-mass stars, predicts SB rotation on extremely short timescales of less than 1 Myr and is therefore unlikely to operate in solar-type pre-main-sequence (pre-MS) and MS stars at the predicted rate. Models with core–envelope decoupling can explain the spin-down of 1.0 and 0.8 solar mass slow rotators with characteristic coupling timescales of 55 ± 25 Myr and 175 ± 25 Myr, respectively. The upper envelope of the rotation distribution is more strongly coupled than the lower envelope of the rotation distribution, in accord with theoretical predictions that the angular momentum transport timescale should be shorter for more rapidly rotating stars. Constraints imposed by the solar rotation curve are also discussed. We argue that neither hydrodynamic mechanisms nor our revised and less efficient prescription for the Tayler–Spruit dynamo can reproduce both spin-down and the internal solar rotation profile by themselves. It is likely that a successful model of angular momentum evolution will involve more than one mechanism. Further observational studies, especially of clusters younger than 100 Myr, will provide important additional constraints on the internal rotation of stars and could firmly rule out or confirm the operation of major classes of theoretical mechanisms.
EFFECTS OF DYNAMICAL EVOLUTION OF GIANT PLANETS ON THE DELIVERY OF ATMOPHILE ELEMENTS DURING TERRESTRIAL PLANET FORMATION

Recent observations started revealing the compositions of protostellar disks and planets beyond the solar system. In this paper, we explore how the compositions of terrestrial planets are affected by the dynamical evolution of giant planets. We estimate the initial compositions of the building blocks of these rocky planets by using a simple condensation model, and numerically study the compositions of planets formed in a few different formation models of the solar system. We find that the abundances of refractory and moderately volatile elements are nearly independent of formation models, and that all the models could reproduce the abundances of these elements of the Earth. The abundances of atmophile elements, on the other hand, depend on the scattering rate of icy planetesimals into the inner disk, as well as the mixing rate of the inner planetesimal disk. For the classical formation model, neither of these mechanisms are efficient and the accretion of atmophile elements during the final assembly of terrestrial planets appears to be difficult. For the Grand Tack model, both of these mechanisms are efficient, which leads to a relatively uniform accretion of atmophile elements in the inner disk. It is also possible to have a “hybrid” scenario where the mixing is not very efficient but the scattering is efficient. The abundances of atmophile elements in this case increase with orbital radii. Such a scenario may occur in some of the extrasolar planetary systems, which are not accompanied by giant planets or those without strong perturbations from giants. We also confirm that the Grand Tack scenario leads to the distribution of asteroid analogues where rocky planetesimals tend to exist interior to icy ones, and show that their overall compositions are consistent with S-type and C-type chondrites, respectively.
A novel wide frequency range 65nm CMOS VCO

In this paper a novel ring oscillator based VCO using a programmable low-dropout regulator (LDO) for coarse frequency tuning, which offers wide tuning range, low phase noise and low die area for integer or fractional-N PLLs is proposed. This design is using two paths to cover more frequencies. The high frequency path uses three delay cells, while the lower frequency path enables two more delay cells to reduce the output frequency. The frequency coverage is 2.75 – 3.7 GHz and 4.5 – 5.7 GHz. Finally, the ring oscillator is designed using 65nm TSMC process with a supply voltage of 1.5V for the LDO and 1 - 1.4V for the ring oscillator. The phase noise is -99.78 dBc/Hz at 1MHz offset, while the power consumption of the full design is 29mW.