Miracle-dz/UniFAR-FTUs huggingface dataset:
STEALTH GALAXIES IN THE HALO OF THE MILKY WAY

We predict that there is a population of low-luminosity dwarf galaxies orbiting within the halo of the Milky Way (MW) that have surface brightnesses low enough to have escaped detection in star-count surveys. The overall count of stealth galaxies is sensitive to the presence (or lack) of a low-mass threshold in galaxy formation. These systems have luminosities and stellar velocity dispersions that are similar to those of known ultrafaint dwarf galaxies but they have more extended stellar distributions (half-light radii greater than about 100 pc) because they inhabit dark subhalos that are slightly less massive than their higher surface brightness counterparts. As a result, the typical peak surface brightness is fainter than 30 mag arcsec−2. One implication is that the inferred common mass scale for MW dwarfs may be an artifact of selection bias. If there is no sharp threshold in galaxy formation at low halo mass, then ultrafaint galaxies like Segue 1 represent the high-mass, early-forming tail of a much larger population of objects that could number in the hundreds and have typical peak circular velocities of about 8 km s−1 and masses within 300 pc of about 5 million solar masses. Alternatively, if we impose a low-mass threshold in galaxy formation in order to explain the unexpectedly high densities of the ultrafaint dwarfs, then we expect only a handful of stealth galaxies in the halo of the MW. A complete census of these objects will require deeper sky surveys, 30 m class follow-up telescopes, and more refined methods to identify extended, self-bound groupings of stars in the halo.
Detection of low-metallicity warm plasma in a galaxy overdensity environment at z ̃ 0.2

We present results from the analysis of a multiphase O VI - broad Ly-alpha absorber at z = 0.19236 in the HST/COS spectrum of PG 1121+422. The low and intermediate ionization metal lines in this absorber have a single narrow component, whereas the Ly-alpha has a possible broad component with b(HI) $\sim 71$ km/s. Ionization models favor the low and intermediate ions coming from a $T \sim 8,500$ K, moderately dense photoionized gas with near solar metallicities. The weak O VI requires a separate gas phase that is collisionally ionized. The O VI coupled with BLA suggests $T \sim 3.2 \times 10^5$ K, with significantly lower metal abundance and $\sim 1.8$ orders of magnitude higher total hydrogen column density compared to the photoionized phase. SDSS shows 12 luminous ($> L^*$) galaxies in the $\rho \leq 5$ Mpc, $|\Delta v| \leq 800$ km/s region surrounding the absorber, with the absorber outside the virial bounds of the nearest galaxy. The warm phase of this absorber is consistent with being transition temperature plasma either at the interface regions between the hot intragroup gas and cooler photoionized clouds within the group, or associated with high velocity gas in the halo of a $\lesssim L^*$ galaxy. The absorber highlights the advantage of O VI-BLA absorbers as ionization model independent probes of warm baryon reserves.
Spectra and rates of bremsstrahlung neutrino emission in stars

We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $\bar{\nu}_e$ and $\bar{\nu}_x$ $(x = {\mu}, {\tau})$ energies, for this process with those for $e^{\pm}$ pair annihilation, plasmon decay, and photo-neutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of $\bar{\nu}_e$ from massive stars during their pre-supernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.
Constraining the Ejecta for the Nonthermal Emission from GW 170817

We consider a simple model for the nonthermal emission from GW 170817, in which a quasi-spherical ejecta is released in the merger event, with the kinetic energy distributed over the momentum as E(>γβ) ∝ (γβ)−k. The ejecta drives a shock into the medium and gives rise to synchrotron radiation. Using multiband observations, we constrain k to be ≈6.7, the total kinetic energy to be (0.3–5) × 1051 erg (assuming the density of the medium to be ∼10−2 cm−3 and the postshock magnetic field to carry a fraction 10−5–10−3 of the postshock internal energy), the slowest ejecta velocity to be ∼(0.7–0.8)c, and the fastest ejecta to have a Lorentz factor of ∼4–7. We conclude that the subrelativistic dynamical ejecta responsible for the kilonova cannot produce nonthermal emission. The coexistence of nonthermal and thermal kilonova emission implies that two simultaneous ejecta are ejected at different angles.
Can the WIMP annihilation boost factor be boosted by the Sommerfeld enhancement

We demonstrate that the Sommerfeld correction to cold dark matter (CDM) annihilations can be appreciable if even a small component of the dark matter is extremely cold. Subhalo substructure provides such a possibility given that the smallest clumps are relatively cold and contain even colder substructure due to incomplete phase space mixing. Leptonic channels can be enhanced for plausible models and the solar neighborhood boost required to account for PAMELA/ATIC data is plausibly obtained, especially in the case of a few TeV mass neutralino for which the Sommerfeld-corrected boost is found to be {approx}10{sup 4}-10{sup 5}. Saturation of the Sommerfeld effect is shown to occur below {beta}{approx}10{sup -4}, thereby making this result largely independent on the presence of substructures below {approx}10{sup 5}M{sub {center_dot}}. We find that the associated diffuse gamma-ray signal from annihilations would exceed EGRET constraints unless the channels annihilating to heavy quarks or to gauge bosons are suppressed. The lepton channel gamma rays are potentially detectable by the FERMI satellite, not from the inner galaxy where substructures are tidally disrupted, but rather as a quasi-isotropic background from the outer halo, unless the outer substructures are much less concentrated than the inner substructures and/or the CDM density profile outmore » to the virial radius steepens significantly. « less
The Paradigm of Projectile Motion and its Consequences for Special Relativity. Making Sense of Physics

The classical (Newtonian) concept of projectile motion underwent a series of seemingly minor changes and adjustments between Planck’s quantum discovery (1900) and Dirac’s early codification of quantum theory (1928). The goal of physicists in this period was to keep change to a minimum and preserve as much as possible of the traditional projectile paradigm (TPP). These adjustments were successful in masking an all-out projectile paradigm crisis, but they have left us with a conceptual muddle. This has been especially deleterious for special relativity and our understanding of space contraction and time dilation.
SEDiff: scope-aware differential fuzzing to test internal function models in symbolic execution

Symbolic execution has become a foundational program analysis technique. Performing symbolic execution unavoidably encounters internal functions (e.g., library functions) that provide basic operations such as string processing. Many symbolic execution engines construct internal function models that abstract function behaviors for scalability and compatibility concerns. Due to the high complexity of constructing the models, developers intentionally summarize only partial behaviors of a function, namely modeled functionalities, in the models. The correctness of the internal function models is critical because it would impact all applications of symbolic execution, e.g., bug detection and model checking. A naive solution to testing the correctness of internal function models is to cross-check whether the behaviors of the models comply with their corresponding original function implementations. However, such a solution would mostly detect overwhelming inconsistencies concerning the unmodeled functionalities, which are out of the scope of models and thus considered false reports. We argue that a reasonable testing approach should target only the functionalities that developers intend to model. While being necessary, automatically identifying the modeled functionalities, i.e., the scope, is a significant challenge. In this paper, we propose a scope-aware differential testing framework, SEDiff, to tackle this problem. We design a novel algorithm to automatically map the modeled functionalities to the code in the original implementations. SEDiff then applies scope-aware grey-box differential fuzzing to relevant code in the original implementations. It also equips a new scope-aware input generator and a tailored bug checker that efficiently and correctly detect erroneous inconsistencies. We extensively evaluated SEDiff on several popular real-world symbolic execution engines targeting binary, web and kernel. Our manual investigation shows that SEDiff precisely identifies the modeled functionalities and detects 46 new bugs in the internal function models used in the symbolic execution engines.
Effect of pressure on transport and magnetotransport properties in CaFe2As2 single crystals

The effects of pressure generated in a liquid medium, clamp, pressure cell on the in-plane and c-axis resistance, temperature-dependent Hall coefficient and low temperature, magnetoresistance in CaFe2As2 are presented. The T - P phase diagram, including the observation of a complete superconducting transition in resistivity, delineated in earlier studies is found to be highly reproducible. The Hall resistivity and low temperature magnetoresistance are sensitive to different states/phases observed in CaFe2As2. Auxiliary measurements under uniaxial, c-axis, pressure are in general agreement with the liquid medium clamp cell results with some difference in critical pressure values and pressure derivatives. The data may be viewed as supporting the potential importance of non-hydrostatic components of pressure in inducing superconductivity in CaFe2As2.
A spectral synthesis code for rapid modelling of supernovae

We present TARDIS - an open-source code for rapid spectral modelling of supernovae (SNe). Our goal is to develop a tool that is sufficiently fast to allow exploration of the complex parameter spaces of models for SN ejecta. This can be used to analyse the growing number of high-quality SN spectra being obtained by transient surveys. The code uses Monte Carlo methods to obtain a self-consistent description of the plasma state and to compute a synthetic spectrum. It has a modular design to facilitate the implementation of a range of physical approximations that can be compared to asses both accuracy and computational expediency. This will allow users to choose a level of sophistication appropriate for their application. Here, we describe the operation of the code and make comparisons with alternative radiative transfer codes of differing levels of complexity (SYN++, PYTHON, and ARTIS). We then explore the consequence of adopting simple prescriptions for the calculation of atomic excitation, focussing on four species of relevance to Type Ia supernova spectra - Si II, S II, Mg II, and Ca II. We also investigate the influence of three methods for treating line interactions on our synthetic spectra and the need for accurate radiative rate estimates in our scheme.
Effective and scalable fault injection using bug reports and generative language models

Previous research has shown that artificial faults can be useful in many software engineering tasks such as testing, fault-tolerance assessment, debugging, dependability evaluation, risk analysis, etc. However, such artificial-fault-based applications can be questioned or inaccurate when the considered faults misrepresent real bugs. Since typically, fault injection techniques (i.e. mutation testing) produce a large number of faults by altering ”blindly” the code in arbitrary locations, they are unlikely capable to produce few but relevant real-like faults. In our work, we tackle this challenge by guiding the injection towards resembling bugs that have been previously introduced by developers. For this purpose, we propose iBiR, the first fault injection approach that leverages information from bug reports to inject ”realistic” faults. iBiR injects faults on the locations that are more likely to be related to a given bug-report by applying appropriate inverted fix-patterns, which are manually or automatically crafted by automated-program-repair researchers. We assess our approach using bugs from the Defects4J dataset and show that iBiR outperforms significantly conventional mutation testing in terms of injecting faults that semantically resemble and couple with real ones, in the vast majority of the cases. Similarly, the faults produced by iBiR give significantly better fault-tolerance estimates than conventional mutation testing in around 80% of the cases.
Neutron scattering study of spin ordering and stripe pinning in superconducting La$_{1.93}$Sr$_{0.07}$CuO$_4$

The relationships among charge order, spin fluctuations, and superconductivity in underdoped cuprates remain controversial. We use neutron scattering techniques to study these phenomena in La1.93Sr0. 07CuO4 a superconductor with a transition temperature of Tc = 20 K. At T<< Tc, we find incommensurate spin fluctuations with a quasielastic energy spectrum and no sign of a gap within the energy range from 0.2 to 15 meV. A weak elastic magnetic component grows below ~ 10 K, consistent with results from local probes. Regarding the atomic lattice, we have discovered unexpectedly strong fluctuations of the CuO6 octahedra about Cu-O bonds, which are associated with inequivalent O sites within the CuO2 planes. Moreover, we observed a weak elastic (3 ⁻30) superlattice peak that implies a reduced lattice symmetry. The presence of inequivalent O sites rationalizes various pieces of evidence for charge stripe order in underdoped La2-xSrxCuO4. The coexistence of superconductivity with quasi-static spin-stripe order suggests the presence of intertwined orders; however, the rotation of the stripe orientation away from the Cu-O bonds might be connected with evidence for a finite gap at the nodal points of the superconducting gap function.
The Bok Globule BHR 160: structure and star formation

BHR 160 is a virtually unstudied cometary globule within the Sco OB4 association in Scorpius at a distance of 1600pc. It is part of a system of cometary clouds which face the luminous O star HD155806. BHR 160 is special because it has an intense bright rim. We attempt to derive physical parameters for BHR 160 and to understand its structure and the origin of its peculiar bright rim. BHR 160 was mapped in the $^{12}$CO, $^{13}$CO and C$^{18}$O (2-1) and (1-0) and CS (3-2) and (2-1) lines. These data, augmented with stellar photometry derived from the ESO VVV survey, were used to derive the mass and distribution of molecular material in BHR 160 and its surroundings. Archival mid-infrared data from the WISE satellite was used to find IR excess stars in the globule and its neighbourhood. An elongated 1' by 0.6' core lies adjacent to the globule bright rim. $^{12}$CO emission covers the whole globule, but the $^{13}$CO, C$^{18}$O and CS emission is more concentrated to the core. The $^{12}$CO line profiles indicate the presence of outflowing material near the core, but the spatial resolution of the mm data is not sufficient for a detailed spatial analysis. The BHR 160 mass estimated from the C$^{18}$O mapping is 100$\pm$50Msun(d/1.6kpc)$^2$ where d is the distance to the globule. Approximately 70 percent of the mass lies in the dense core. The total mass of molecular gas in the direction of BHR 160 is 210$\pm$(d/1.6kpc)$^2$ Msun when estimated from the more extended VVV NIR photometry. We argue that the bright rim of BHR 160 is produced by a close-by early B-type star, HD 319648, that was likely recently born in the globule. This star is likely to have triggered the formation of a source, IRS 1, that is embedded within the core of the globule and detected only in Ks and by WISE and IRAS.
AMUSE-VIRGO. III. MID-INFRARED PHOTOMETRY OF EARLY-TYPE GALAXIES AND LIMITS ON OBSCURED NUCLEAR EMISSION

We complete our census of low-level nuclear activity in Virgo Cluster early-type galaxies by searching for obscured emission using Spitzer Space Telescope mid-infrared (MIR) imaging at 24 μm. Of a total sample of 95 early-type galaxies, 53 objects are detected, including 16 showing kiloparsec-scale dust in optical images. One-dimensional and two-dimensional surface photometry of the 37 detections without extended dust features reveals that the MIR light is more centrally concentrated than the optical light as traced by Hubble Space Telescope F850LP-band images. No such modeling was performed for the sources with dust detected in the optical images. We explore several possible sources of the MIR excess emission, including obscured nuclear emission. We find that radial metallicity gradients in the stellar population appear to be a natural and most likely explanation for the observed behavior in a majority of the sources. Alternatively, if the concentrated MIR emission were due to nuclear activity, it would imply a MIR-to-X luminosity ratio ∼5–10 for the low-luminosity active galactic nucleus (AGN) detected in X-rays by our survey. This ratio is an order of magnitude larger than that of typical low-luminosity AGNs and would imply an unusual spectral energy distribution. We conclude that the black holes found by our survey in quiescent early-type galaxies in Virgo have low bolometric Eddington ratios arising from low accretion rates and/or highly radiatively inefficient accretion.
Detecting non-crashing functional bugs in Android apps via deep-state differential analysis

Non-crashing functional bugs of Android apps can seriously affect user experience. Often buried in rare program paths, such bugs are difficult to detect but lead to severe consequences. Unfortunately, very few automatic functional bug oracles for Android apps exist, and they are all specific to limited types of bugs. In this paper, we introduce a novel technique named deep-state differential analysis, which brings the classical "bugs as deviant behaviors" oracle to Android apps as a generic automatic test oracle. Our oracle utilizes the observations on the execution of automatically generated test inputs that (1) there can be a large number of traces reaching internal app states with similar GUI layouts, and only a small portion of them would reach an erroneous app state, and (2) when performing the same sequence of actions on similar GUI layouts, the outcomes will be limited. Therefore, for each set of test inputs terminating at similar GUI layouts, we manifest comparable app behaviors by appending the same events to these inputs, cluster the manifested behaviors, and identify minorities as possible anomalies. We also calibrate the distribution of these test inputs by a novel input calibration procedure, to ensure the distribution of these test inputs is balanced with rare bug occurrences. We implemented the deep-state differential analysis algorithm as an exploratory prototype Odin and evaluated it against 17 popular real-world Android apps. Odin successfully identified 28 non-crashing functional bugs (five of which were previously unknown) of various root causes with reasonable precision. Detailed comparisons and analyses show that a large fraction (11/28) of these bugs cannot be detected by state-of-the-art techniques.
Challenges and possible approaches for sustainable digital twinning

The advance in digital twin technology is creating value for lots of companies. We look at the digital twin design and operation from a sustainability perspective. We identify some challenges related to a digital twin's sustainable design and operation. Finally, we look at some possible approaches, grounded in multi-paradigm modelling to help us create and deploy more sustainable twins.
On the retrieval of attenuation from the azimuthally averaged coherency of a diffuse field

It has been suggested that seismic attenuation \alpha can be inferred from comparisons of empirical coherencies (the cross spectra of pre-whitened ambient seismic noise records) with attenuated Bessel functions Jo(\omega r/c) exp(-\alpha r). Analysis shows here, however, that coherency depends strongly on the directionality of ambient noise intensity. Even if coherency is azimuthally averaged, the suggested attenuation dependence exp(-\alpha r) does not apply. Indeed in highly directional noise fields, coherency is independent of attenuation. It is also argued that spatial and azimuthal averages of coherency can incur phase cancellations related to variations in wavespeed that may mimic factors like exp(-\alpha r). Inference of attenuation from comparison of empirical coherencies to Jo(\omega r/c) exp(-\alpha r) is problematic.
Fundamental parameters of RR Lyrae stars from multicolour photometry and Kurucz atmospheric models – II. Adaptation to double-mode stars

Our photometric–hydrodynamic method is generalized to determine the fundamental parameters of multiperiodic radially pulsating stars. We report 302 UBV(RI)C Johnson–Kron–Cousins observations of GSC 4868–0831. Using these and the published photometric data of V372 Ser, we determine the metallicity, reddening, distance, mass, radius, equilibrium luminosity and effective temperature. The results underline the necessity of using multicolour photometry, including an ultraviolet band, to classify the subgroups of RR Lyrae stars properly. Our U observations might reveal that GSC 4868–0831 is a subgiant star pulsating in two radial modes and that V372 Ser is a giant star with the size and mass of an RRd star.
NICIL: A Stand Alone Library to Self-Consistently Calculate Non-Ideal Magnetohydrodynamic Coefficients in Molecular Cloud Cores

Abstract In this paper, we introduce Nicil: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library. Nicil is a stand-alone Fortran90 module that calculates the ionisation values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. The module is fully parameterised such that the user can decide which processes to include and decide upon the values of the free parameters, making this a versatile and customisable code. The module includes both cosmic ray and thermal ionisation; the former includes two ion species and three species of dust grains (positively charged, negatively charged, and neutral), and the latter includes five elements which can be doubly ionised. We demonstrate tests of the module, and then describe how to implement it into an existing numerical code.
Model-checking of space systems designed with TASTE/SDL

Model-Based Software Engineering (MBSE) is a development approach aiming to build correct-by-construction systems, provided the use of clear, unambiguous and complete models to describe them along the design process. The approach is supported by several engineering tools, such as the TASTE toolset. TASTE is a pragmatic and mature open-source toolset supported by European Space Agency that enables and provides automation for most of the phases of software system development: (i) heterogeneous system design through several modelling and programming languages, (ii) code generation, build and deployment of the binary application(s), and (iii) validation through static analysis and simulation. One topic left open in TASTE is the formal verification of a system design with respect to specified properties. In this paper we describe our approach based on the IF model-checker to enable the formal verification of properties on TASTE designs, as well as the results obtained and lessons learned.