Miracle-dz/UniFAR-FTUs huggingface dataset:
The Complex Broadband X-Ray Spectrum of the Starburst Galaxy M82

The broadband X-ray spectrum of the prototypical starburst galaxy M82 is very complex. At least three spectral components are required to fit the combined ROSAT and ASCA spectrum in the 0.1-10 keV range. The observed X-ray flux in this band is dominated by a hard Γ = 1.7, heavily absorbed power-law component which originates in the nucleus and near-nuclear disk of the galaxy. Among the candidates for the origin of this hard X-ray emission, the most plausible appears to be inverse-Compton scattered emission from the interaction of the copious infrared photon flux of M82 with supernova-generated relativistic electrons. The measured intrinsic luminosity of the power-law component agrees closely with calculations of the expected inverse-Compton luminosity. Moreover, the radio and X-ray emission in the nucleus of M82 have the same spectral slope, which should be the case if both types of emission are nonthermal and are associated with a common population of electrons. The other two spectral components, thermal plasmas with characteristic temperatures kT ≈ 0.6 and 0.3 keV, are associated with the star formation and starburst-driven wind in M82. The warmer thermal component is heavily absorbed as well and must also originate in the central region of the galaxy. The softer thermal component, however, is not absorbed, and is likely to represent the X-ray emission that extends along the minor axis of M82. The amount of absorption required in the three-component model suggests that the intrinsic luminosity of M82 in the 0.1-10 keV band is about four times greater than its observed luminosity of 4 × 1040 ergs s-1.
Correlations in star networks: from Bell inequalities to network inequalities

The problem of characterizing classical and quantum correlations in networks is considered. Contrary to the usual Bell scenario, where distant observers share a physical system emitted by one common source, a network features several independent sources, each distributing a physical system to a subset of observers. In the quantum setting, the observers can perform joint measurements on initially independent systems, which may lead to strong correlations across the whole network. In this work, we introduce a technique to systematically map a Bell inequality to a family of Bell-type inequalities bounding classical correlations on networks in a star-configuration. Also, we show that whenever a given Bell inequality can be violated by some entangled state ρ, then all the corresponding network inequalities can be violated by considering many copies of ρ distributed in the star network. The relevance of these ideas is illustrated by applying our method to a specific multi-setting Bell inequality. We derive the corresponding network inequalities, and study their quantum violations.
Non-local magnon transport in the compensated ferrimagnet GdIG

We study the diffusive transport of magnons through the compensated ferrimagnetic insulator Gd3Fe5O12 (GdIG). The magnons are injected and detected electrically in a non-local measurement configuration via two parallel Pt strips deposited on top of the ferrimagnet. GdIG exhibits a rich magnon spectrum, with several thermally populated magnon bands at room temperature. We observe a strong temperature and field dependence of the non-local voltage in the detector strip. Just below the magnetization compensation temperature we find that the increasing magnetic field causes an unexpected enhancement of the non-local signal. A comparison with GdIG spin wave spectra obtained from atomistic modeling indicates that the thermal magnon population is important for understanding the non-local voltage signal.
Spectroscopic Confirmation of Three Redshift z ≈ 5.7 Lyα Emitters from the Large-Area Lyman Alpha Survey

Narrowband searches for Lyα emission are an efficient way of identifying star-forming galaxies at high redshifts. We present Keck Telescope spectra confirming redshifts z ≈ 5.7 for three objects discovered in the Large-Area Lyman Alpha (LALA) survey at Kitt Peak National Observatory. All three spectra show strong, narrow emission lines with the asymmetric profile that is characteristically produced in high-redshift Lyα emitters by preferential H I absorption in the blue wing of the line. These objects are undetected in deep BW, V, R, and λ ≈ 6600 Å narrowband images from the NOAO Deep Wide-Field Survey and from LALA, as expected from Lyman break and Lyα forest absorption at redshift z ≈ 5.7. All three objects show large equivalent widths (≳150 Å in the rest frame), suggesting at least one of the following: a top-heavy initial mass function, very low stellar metallicity, or the presence of an active nucleus. We consider the case for an active nucleus to be weak in all three objects due to the limited width of the Lyα emission line (less than 500 km s-1) and the absence of any other indicator of quasar activity. The three confirmed high-redshift objects were among four spectroscopically observed targets drawn from the sample of 18 candidates presented by Rhoads & Malhotra. Thus, these spectra support the Lyα emitter population statistics from our earlier photometric study, which imply little evolution in number density from z = 5.7 to 4.5 and provide strong evidence that the reionization redshift is zr > 5.7.
Magnetohydrodynamic Models of Molecular Tornadoes

Recent observations near the Galactic Center (GC) have found several molecular filaments displaying striking helically wound morphology that are collectively known as molecular tornadoes. We investigate the equilibrium structure of these molecular tornadoes by formulating a magnetohydrodynamic model of a rotating, helically magnetized filament. A special analytical solution is derived where centrifugal forces balance exactly with toroidal magnetic stress. From the physics of torsional Alfvén waves we derive a constraint that links the toroidal flux-to-mass ratio and the pitch angle of the helical field to the rotation laws, which we find to be an important component in describing the molecular tornado structure. The models are compared to the Ostriker solution for isothermal, nonmagnetic, nonrotating filaments. We find that neither the analytic model nor the Alfvén wave model suffer from the unphysical density inversions noted by other authors. A Monte Carlo exploration of our parameter space is constrained by observational measurements of the Pigtail Molecular Cloud, the Double Helix Nebula, and the GC Molecular Tornado. Observable properties such as the velocity dispersion, filament radius, linear mass, and surface pressure can be used to derive three dimensionless constraints for our dimensionless models of these three objects. A virial analysis of these constrained models is studied for these three molecular tornadoes. We find that self-gravity is relatively unimportant, whereas magnetic fields and external pressure play a dominant role in the confinement and equilibrium radial structure of these objects.
Luminosity Functions of 10 Nearby Clusters of Galaxies. II. Analysis of the Luminosity Function

We investigate the total luminosity function (LF) and the type-specific luminosity functions (TSLFs)of r1/4-like galaxies and exponential-like galaxies in 10 nearby clusters. The composite total LF of the 10clusters is described well by the Schechter function with M = -21.3 and α = -1.31 in the range -23.5 < MR + 5 log h < -16. This value of α is consistent with the previous results for cluster galaxies. An extensive comparison of the values of α is made between clusters and fields. We find that the total LF of cluster galaxies has a steeper faint end slope than that of field galaxies. In contrast to the composite total LF, the individual total LFs of some clusters are not fitted well by the Schechter function. They show a hump around MR ∼ -20 to -19 associated with a dip around MR ∼ -19 to -18. The composite TSLFs of both r1/4-like galaxies and exponential-like galaxies are fitted well by the Schechter function. The best-fit parameters are (M = -21.2, α = -1.08) for the former and (M = -21.1, α = -1.49) for the latter. When seen on a cluster to cluster basis, however, the TSLFs of the two types of galaxies show different behaviors. The TSLF of r1/4-like galaxies shows a considerable diversity among the clusters, while the TSLF of exponential-like galaxies is similar in all the clusters. We demonstrate that the dip at MR ∼ -19 to -18 seen in the total LFs of some clusters is almost entirely due to r1/4-like galaxies, rather than exponential-like galaxies. We find that the dip of the TSLF of r1/4-like galaxies is correlated with the velocity dispersion of the cluster in the sense that clusters with larger velocity dispersion show more distinct dips.
Ultraviolet Emission and Star Formation in Stephan’s Quintet

We present the first Galaxy Evolution Explorer (GALEX) UV images of the well-known interacting group of galaxies, Stephan's Quintet (SQ). We detect widespread UV emission throughout the group. However, there is no consistent coincidence between UV structure and emission in the optical, Hα, or H I. Excluding the foreground galaxy NGC 7320 (Sd), most of the UV emission is found in regions associated with the two spiral members of the group, NGC 7319 and NGC 7318b, and the intragroup medium starburst SQ-A. The extinction-corrected UV data are analyzed to investigate the overall star formation activity in SQ. We find that the total star formation rate (SFR) of SQ is 6.69 ± 0.65 M☉ yr-1. Of this, 1.34 ± 0.16 M☉ yr-1 is due to SQ-A. This is in excellent agreement with that derived from the extinction-corrected Hα luminosity of SQ-A. The SFR in regions related to NGC 7319 is 1.98 ± 0.58 M☉ yr-1, most of which (68%) is contributed by the disk. The contribution from the "young tail" is only 15%. In the UV, the young tail is more extended (~100 kpc) and shows a looplike structure, including the optical tail, the extragalactic H II regions recently discovered in Hα, and other UV emission regions discovered for the first time. The UV and optical colors of the "old tail" are consistent with a single stellar population of age t ≃ 108.5±0.4 yr. The UV emission associated with NGC 7318b is found in a very large (~80 kpc) disk, with a net SFR of 3.37 ± 0.25 M☉ yr-1. Several large UV emission regions are 30-40 kpc away from the nucleus of NGC 7318b. Although both NGC 7319 and NGC 7318b show peculiar UV morphology, their SFR is consistent with that of normal Sbc galaxies, indicating that the strength of star formation activity is not enhanced by interactions.
On the Neutrino Distributions in Phase Space for the Rotating Core-collapse Supernova Simulated with a Boltzmann-neutrino-radiation-hydrodynamics Code

With the Boltzmann-radiation-hydrodynamics code, which we have developed to solve numerically the Boltzmann equations for neutrino transfer, the Newtonian hydrodynamics equations, and the Newtonian self-gravity simultaneously and consistently, we simulate the collapse of a rotating core of the progenitor with a zero-age- main-sequence mass of 11.2 M⊙ and a shellular rotation of at the center. We pay particular attention in this paper to the neutrino distribution in phase space, which is affected by the rotation. By solving the Boltzmann equations directly, we can assess the rotation-induced distortion of the angular distribution in momentum space, which gives rise to the rotational component of the neutrino flux. We compare the Eddington tensors calculated both from the raw data and from the M1-closure approximation. We demonstrate that the Eddington tensor is determined by complicated interplays of the fluid velocity and the neutrino interactions and that the M1-closure, which assumes that the Eddington factor is determined by the flux factor, fails to fully capture this aspect, especially in the vicinity of the shock. We find that the error in the Eddington factor reaches ∼20% in our simulation. This is due not to the resolution but to the different dependence of the Eddington and flux factors on the angular profile of the neutrino distribution function, and hence modification to the closure relation is needed.
Determining Neutrino Mass from the CMB Alone

Distortions of Cosmic Microwave Background (CMB) temperature and polarization maps caused by gravitational lensing, observable with high angular resolution and high sensitivity, can be used to measure the neutrino mass. Assuming two massless species and one with mass m ν we forecast σ ( m ν ) = 0 . 15 eV from the Planck satellite and σ ( m ν ) = 0 . 04 eV from observations with twice the angular resolution and ∼ 20 times the sensitivity. A detection is likely at this higher sensitivity since the observation of atmospheric neutrino oscillations require ∆ m 2 ν > ∼ (0 . 04eV) 2 .
Analytical solution of ttbar dilepton equations

The top quark antiquark production system in the dilepton decay channel is described by a set of equations which is nonlinear in the unknown neutrino momenta. Its most precise and least time consuming solution is of major importance for measurements of top quark properties like the top quark mass and $t\bar{t}$ spin correlations. The initial system of equations can be transformed into two polynomial equations with two unknowns by means of elementary algebraic operations. These two polynomials of multidegree two can be reduced to one univariate polynomial of degree four by means of resultants. The obtained quartic equation is solved analytically.
Mode classification in fast-rotating stars using a convolutional neural network: model-based regular patterns in δ Scuti stars

Oscillation modes in fast-rotating stars can be split into several subclasses, each with their own properties. To date, seismology of these stars cannot rely on regular pattern analysis and scaling relations. However, recently there has been the promising discovery of large separations observed in spectra of fast-rotating δ Scuti stars; they were attributed to the island-mode subclass, and linked to the stellar mean density through a scaling law. In this work, we investigate the relevance of this scaling relation by computing models of fast-rotating stars and their oscillation spectra. In order to sort the thousands of oscillation modes thus obtained, we train a convolutional neural network isolating the island modes with 96 per cent accuracy. Arguing that the observed large separation is systematically smaller than the asymptotic one, we retrieve the observational Δν--ρ¯¯¯ scaling law. This relation will be used to drive forward modelling efforts, and is a first step towards mode identification and inversions for fast-rotating stars.
The origins of the circumgalactic medium in the FIRE simulations

We use a particle tracking analysis to study the origins of the circumgalactic medium (CGM), separating it into (1) accretion from the intergalactic medium (IGM), (2) wind from the central galaxy, and (3) gas ejected from other galaxies. Our sample consists of 21 FIRE-2 simulations, spanning the halo mass range Mh ∼ 1010–1012 M⊙, and we focus on z = 0.25 and z = 2. Owing to strong stellar feedback, only ∼L⋆ haloes retain a baryon mass $\gtrsim\! 50\hbox{ per cent}$ of their cosmic budget. Metals are more efficiently retained by haloes, with a retention fraction $\gtrsim\! 50\hbox{ per cent}$. Across all masses and redshifts analysed $\gtrsim \! 60\hbox{ per cent}$ of the CGM mass originates as IGM accretion (some of which is associated with infalling haloes). Overall, the second most important contribution is wind from the central galaxy, though gas ejected or stripped from satellites can contribute a comparable mass in ∼L⋆ haloes. Gas can persist in the CGM for billions of years, resulting in well mixed-halo gas. Sightlines through the CGM are therefore likely to intersect gas of multiple origins. For low-redshift ∼L⋆ haloes, cool gas (T < 104.7 K) is distributed on average preferentially along the galaxy plane, however with strong halo-to-halo variability. The metallicity of IGM accretion is systematically lower than the metallicity of winds (typically by ≳1 dex), although CGM and IGM metallicities depend significantly on the treatment of subgrid metal diffusion. Our results highlight the multiple physical mechanisms that contribute to the CGM and will inform observational efforts to develop a cohesive picture.
Superconducting fluctuations in the Luther-Emery liquid

The single-particle superconducting Green\'s functions of a Luther-Emery liquid is computed by bosonization techniques. Using a formulation introduced by Poilblanc and Scalapino [Phys. Rev. B v. 66, art. 052513 (2002)], an asymptotic expression of the superconducting gap is deduced in the long wavelength and small frequency limit. Due to superconducting phase fluctuations, the gap exhibits as a function of size L a (1/L)^{1/2K_\\rho} power-law decay as well as an interesting singularity at the spectral gap energy. Similarities and differences with the 2-leg t-J ladder are outlined.
Coherent terahertz emission with tunable ellipticity and optical chirality from the Weyl semimetal TaAs

Polarization control of ultrafast coherent light pulses through light-matter interactions in quantum materials holds the key to many technical innovations, including quantum communication, on-chip information processing and storage. Here, we discover strong coherent terahertz emission from the Weyl semimetal TaAs and demonstrate unprecedented manipulation over its polarization and chirality on a femtosecond timescale. Such controllability is achieved via polarization-dependent, colossal ultrafast photocurrents in TaAs generated using the circular and/or linear photogalvanic effect. The experimental results are well supported by theory. Our findings pave the way to design conceptually novel chiral photon sources using quantum materials and open up new opportunities for developing ultrafast opto-electronics in topological Weyl semimetals.
Convergence of relaxation schemes for conservation laws

We study the stability and the convergence for a class of relaxing numerical schemes for conservation laws. Following the approach recently proposed by S. Jin and Z. Xin we use a semilinear local relaxation approximation, with a stiff lower order term, and we construct some numerical first and second order accurate algorithms, which are uniformly bounded in the L∞ and BV norms with respect to the relaxation parameter. The relaxation limit is also investigated.
Parallel DIQKD from parallel repetition

We give an arguably simpler and more direct proof of a recent result by Miller, Jain and Shi, who proved device-independent security of a protocol for quantum key distribution in which the devices can be used in parallel. Our proof combines existing results on immunization (Kempe et al., SICOMP 2011) and parallel repetition (Bavarian et al., STOC 2017) of entangled games.
The life-cycle of star formation in distant clusters

We analyse the detailed distribution of star-forming and post-starburst members in three distant (z = 0.31) galaxy clusters in terms of evolutionary sequences that incorporate secondary bursts of star formation on pre-existing stellar populations. Using the number density of spectroscopically-confirmed members on the EW(H\delta) versus B-R plane from existing data, and for a larger K'-limited sample on the U-I versus I-K' plane from newly-acquired infrared images, we demonstrate that the proportion of cluster members undergoing secondary bursts of star formation during the last ~2 Gyr prior to the epoch of observation is probably as high as 30 per cent of the member galaxies. A key observation leading to this conclusion is the high proportion of H\delta strong galaxies in all three clusters. The evolutionary modelling, whilst necessarily approximate, returns the correct proportions of galaxies in various stages of the star formation cycle both in terms of spectral and colour properties. HST images for the three clusters indicate a high proportion of the active members show signs of interaction, whereas the H\delta strong galaxies appear mainly to be regular spheroidals. We examine results from recent merger simulations in the context of the populations in these clusters and confirm that the merging of individual galaxies, triggered perhaps by the hierarchical assembly of rich clusters at this epoch, is consistent with the star formation cycle identified in our data. The implications of such a high fraction of active objects in cluster cores is briefly discussed.
RX J0806.3+1527: A double degenerate binary with the shortest known orbital 
period (321s)

We carried out optical observations of the field of the X–ray pulsator RX J0806.3+1527. A blue $V =$ 21.1 star was found to be the only object consistent with the X–ray position. VLT FORS spectra revealed a blue continuum with no intrinsic absorption lines. Broad ($v \sim$ 1500 km s -1 ), low equivalent width (~–1 $\div$ –6 A) emission lines from the HeII Pickering series were clearly detected. B , V and R time–resolved photometry revealed the presence of ~15% pulsations at the ~321 s X–ray period, confirming the identification. These findings, together with the period stability and absence of any additional modulation in the 1 min$ - $5 hr period range, argue in favour of the orbital interpretation of the 321 s pulsations. The most likely scenario is thus that RX J0806.3+1527 is a double degenerate system of the AM CVn class. This would make RX J0806.3+1527 the shortest orbital period binary currently known and one of the best candidates for gravitational wave detection.
The ages of (the oldest) stars

Abstract Much progress has been achieved in the age-dating of old stellar systems, and even of individual stars in the field, in the more than sixty years since the evolution of low-mass stars was first correctly described. In this paper, I provide an overview of some of the main methods that have been used in this context, and discuss some of the issues that still affect the determination of accurate ages for the oldest stars.
Elastic scattering of electrons by krypton in the energy range 20–260 eV

Elastic scattering of electrons by krypton atom was investigated both experimentally and theoretically. Differential cross sections (DCSs) were measured at fixed incident energies from 20 eV to 80 eV as a function of scattering angle (10°–150°). From 100 eV, DCSs were measured as a function of both incident electron energy (100–260 eV) and scattering angle (30°–110°), in small steps around minima. The energy dependence of the angular positions of DCS minima was determined. Theoretical results were obtained in terms of a model of phenomenological complex potential with allowance for spin–orbit interaction. Two data sets were calculated, with and without an absorption potential, and compared to experimental results. The improvements and deteriorations in agreement with measurements upon inclusion of absorption effects are discussed.
Control of magnetism in bilayer CrI3 by an external electric field

Recently intrinsic ferromagnetism in two-dimensional(2D) van der Waals materials was discovered (Huang et al 2017 Nature 546 270–3; Gong et al 2017 Nature 546 265–9; O’Hara et al 2018 Nano Lett. 18 3125–31). A monolayer of Chromiun triiodide(CrI3) is ferromagnetic while a bilayer structure was reported to be anti-ferromagnetic, moreover an external electric field changes its magnetic phase (Jiang et al 2018 Nat. Mater. 17 406–10). We have studied the two found in nature stackings of CrI3 bilayers and found that indeed the magnetic phase of one of them can be tuned by an external electric field while the other remains ferromagnetic. We simulate those results with ab initio calculations and explain them with a simple model based on a rigid shift of the bands associated with different spins. The model can be applied to similar van der Waal stacked insulating bilayer anti-ferromagnets.