Miracle-dz/UniFAR-FTUs huggingface dataset:
SHORT GAMMA-RAY BURSTS AND DARK MATTER SEEDING IN NEUTRON STARS

We present a mechanism based on internal self-annihilation of dark matter accreted from the galactic halo in the inner regions of neutron stars that may trigger full or partial conversion into a quark star. We explain how this effect may induce a gamma-ray burst (GRB) that could be classified as short, according to the usual definition based on time duration of the prompt gamma-ray emission. This mechanism differs in many aspects from the most discussed scenario associating short GRBs with compact object binary mergers. We list possible observational signatures that should help distinguish between these two possible classes of progenitors.
Gaussian-mixture-model-based cluster analysis finds five kinds of gamma-ray bursts in the BATSE catalogue

Clustering methods are an important tool to enumerate and describe the different coherent kinds of Gamma Ray Bursts (GRBs). But their performance can be affected by a number of factors such as the choice of clustering algorithm and inherent associated assumptions, the inclusion of variables in clustering, nature of initialization methods used or the iterative algorithm or the criterion used to judge the optimal number of groups supported by the data. We analyzed GRBs from the BATSE 4Br catalog using $k$-means and Gaussian Mixture Models-based clustering methods and found that after accounting for all the above factors, all six variables -- different subsets of which have been used in the literature -- and that are, namely, the flux duration variables ($T_{50}$, $T_{90}$), the peak flux ($P_{256}$) measured in 256-millisecond bins, the total fluence ($F_t$) and the spectral hardness ratios ($H_{32}$ and $H_{321}$) contain information on clustering. Further, our analysis found evidence of five different kinds of GRBs and that these groups have different kinds of dispersions in terms of shape, size and orientation. In terms of duration, fluence and spectrum, the five types of GRBs were characterized as intermediate/faint/intermediate, long/intermediate/soft, intermediate/intermediate/intermediate, short/faint/hard and long/bright/intermediate.
Diffuser-assisted Photometric Follow-up Observations of the Neptune-sized Planets K2-28b and K2-100b

We present precision transit observations of the Neptune-sized planets K2-28b and K2-100b using the Engineered Diffuser on the Astrophysical Research Council Telescope Imaging Camera (ARCTIC) imager on the ARC 3.5 m Telescope at Apache Point Observatory. K2-28b is a Rp = 2.56 R⊕ mini-Neptune transiting a bright (J = 11.7) metal-rich M4 dwarf offering compelling prospects for future atmospheric characterization. K2-100b is an Rp = 3.45 R⊕ Neptune in the Praesepe Cluster and is one of few planets known in a cluster transiting a host star bright enough (V = 10.5) for precision radial velocity observations. Using the precision photometric capabilities of the diffuser/ARCTIC system allows us to achieve a precision of 365 ppm and 70 ppm in 30-minute bins for K2-28b and K2-100b, respectively. Our joint-fits to the K2 and ground-based light curves give an order-of-magnitude improvement in the orbital ephemeris for both planets, yielding a timing precision of 2 minutes in the James Webb Space Telescope (JWST) era. Although we show that the currently available broad-band measurements of K2-28b’s radius are currently too imprecise to place useful constraints on K2-28b’s atmosphere, we demonstrate that JWST/NIRISS will be able to discern between a cloudy/clear atmosphere in a modest number of transit observations. Our light curve of K2-100b marks the first transit follow-up observation of this challenging-to-observe transit, where we obtain a transit depth of 822 ± 50 ppm in the SDSS i′ band. We conclude that diffuser-assisted photometry can play an important role in the Transiting Exoplanet Survey Satellite (TESS) era to perform timely and precise follow-up of the expected bounty of TESS planet candidates.
Versatile engineering of multimode squeezed states by optimizing the pump spectral profile in spontaneous parametric down-conversion

We study the quantum correlations induced by spontaneous parametric down-conversion of a frequency comb. We derive a theoretical method to find the output state corresponding to a pump with an arbitrary spectral profile. After applying it to the relevant example of a spectrally chirped pump, we run an optimization algorithm to numerically find the pump profiles maximizing some target functions. These include the number of independently squeezed modes and the variances of nullifiers defining cluster states used in many continuous-variable quantum information protocols. To assess the advantages of pump shaping in real experiments, we take into account the physical limitations of the pulse shaper.
WIYN Open Cluster Study. LXXV. Testing the Metallicity Dependence of Stellar Lithium Depletion Using Hyades-aged Clusters. I. Hyades and Praesepe

WIYN/Hydra spectroscopy (at R ∼ 15,000) of the moderately metal-rich Praesepe and Hyades open clusters was used to study their main-sequence (MS) iron ([Fe/H]) and lithium (A(Li)) abundances. Self-consistent [Fe/H] and Li analyses of these clusters of consistent age, which we re-evaluate, confirms that they have consistent [Fe/H] and provides a foundation to investigate the poorly understood G-dwarf and F-dwarf Li-depletions. Neither phenomenon agrees with standard stellar evolution theory, but possible explanations abound. We supplement our A(Li) with previously published results placed on a uniform abundance scale. This creates the largest self-consistently analyzed sample of A(Li) in both the Hyades (90) and Praesepe (110). For each star, high-precision UBVRI photometry was used to determine a 10-color-based and then to test for photometric peculiarities indicated by a large (>75 K). The stars that have large were predominantly found to be binaries or stars with peculiar (apparent) A(Li). When considering only proper-motion members that have low and are also photometrically consistent with the cluster MS fiducial, each cluster has a more tightly defined Li morphology than previously observed and the two clusters’ A(Li) are indistinguishable. This suggests that clusters of consistent age and metallicity may have consistent Li-depletion trends across a broad range of no additional major parameters are required, at least for these two clusters. We propose that the combined Hyades and Praesepe data offer more rigorous constraints than does either cluster alone, and we discuss newly revealed features of the combined Li– trend.
The gap of stellar mass in galaxy groups: another perspective of the Too-big-To-Fail problem in the Milky Way

The Milky Way presents the too-big-to-fail (TBTF) problem that there are two observed satellite galaxies with maximum circular velocity larger than 55km/s, and others have velocity less than 25km/s, but the cold dark matter model predicts there should be more than 10 subhaloes with velocity larger than 25km/s. Those massive subhaloes with $25km/s<V_{max}<55km/s$ should not have failed to form stars. The TBTF problem severely challenges the CDM model. Most efforts are seeking the effects of baryonic feedback, decreasing the mass of the Milky Way, changing the properties of dark matter, so as to assign the observed low-velocity satellites into the massive subhaloes found in simulations. However, the TBTF problem can be avoided if the MW have not accreted subhaloes with velocity between $25km/s<V_{max}<55km/s$ although the probability of such a gap is lower as $\sim 1\%$ and can not be tested against observations. In this work we study the gap in stellar mass of satellite galaxies using the SDSS group catalogue and a semi-analytical model. We find that there are 1-2\% of galaxy groups with a large gap in the stellar mass of their satellites. These 'big gap' groups have accreted less massive subhaloes in their formation history and naturally display a gap between their satellite galaxies. If extrapolating our results to the Milky Way is appropriate, we conclude that it is very likely that our Milky Way has not accreted enough massive subhaloes to host those low-velocity satellites, and the TBTF problem is naturally avoided.
Crystalline order on catenoidal capillary bridges

We study the defect structure of crystalline particle arrays on negative Gaussian curvature capillary bridges with vanishing mean curvature (catenoids). The threshold aspect ratio for the appearance of isolated disclinations is found and the optimal positions for dislocations determined. We also discuss the transition from isolated disclinations to scars as particle number and aspect ratio are varied.
Timing and broad-band spectroscopy of 1A 1118−61 with Suzaku

We present a timing and broad-band pulse-phase-resolved spectral analysis of the transient Be X-ray binary pulsar 1A 1118-61 observed during its outburst in 2009 January using Suzaku observations. The Suzaku observations were made twice, once at the peak of the outburst, and the other 13 d later at its declining phase. Pulse profiles from both observations exhibit strong energy dependence with several peaks at low energies and a single peak above similar to 10 keV. A weak, narrow peak is detected at the main dip of the pulse profiles from both observations in the energy bands below 3 keV, indicating the presence of a phase-dependent soft excess in the source continuum. The broad-band energy spectrum of the pulsar could be fitted well with a partial covering cut-off power-law model and a narrow iron fluorescence line. We also detect a broad cyclotron feature at similar to 50 keV from both observations which is a feature common for accretion-powered pulsars with high magnetic field strength. The pulse-phase-resolved spectral analysis shows an increase in the absorption column density of the partial covering component, as well as variation in the covering fraction at the dips of the pulse profiles, which naturally explains energy dependence of the same. The cyclotron line parameters also show significant variation with pulse phase with an similar to 10 keV variation in the cyclotron line energy and a variation in depth by a factor of 3. This can be explained either as the effect of different viewing angles of the dipole field at different pulse phases, or due to a more complex underlying magnetic field geometry.
Less space for a new family of fermions

We investigate the experimentally allowed parameter space of an extension of the standard model (SM3) by one additional family of fermions. Therefore we extend our previous study of the Cabibbo-Kobayashi-Maskawa (CKM)-like mixing constraints of a fourth generation of quarks. In addition to the bounds from tree-level determinations of the 3x3 CKM elements and flavor-changing neutral currents processes (K, D, B{sub d}, B{sub s} mixing and the decay b{yields}s{gamma}) we also investigate the electroweak S, T, U parameters, the angle {gamma} of the unitarity triangle, and the rare decay B{sub s}{yields}{mu}{sup +}{mu}{sup -}. Moreover we improve our treatment of the QCD corrections compared to our previous analysis. We also take leptonic contributions into account, but we neglect the mixing among leptons. As a result we find that typically small mixing with the fourth family is favored, but still some sizeable deviations from the SM3 results are not yet excluded. The minimal possible value of V{sub tb} is 0.93. Also very large CP-violating effects in B{sub s} mixing seem to be impossible within an extension of the SM3 that consists of an additional fermion family alone. We find a delicate interplay of electroweak and flavor observables, which strongly suggests that a separatemore » treatment of the two sectors is not feasible. In particular we show that the inclusion of the full CKM dependence of the S and T parameters in principle allows the existence of a degenerate fourth generation of quarks. « less
The Role of Cosmic-ray Transport in Shaping the Simulated Circumgalactic Medium

The majority of galactic baryons resides outside of the galactic disk in the diffuse gas known as the circumgalactic medium (CGM). While state-of-the art simulations excel at reproducing galactic disk properties, many of them struggle to drive strong galactic winds or to match the observed ionization structure of the CGM using only thermal supernova feedback. To remedy this, recent studies have invoked nonthermal cosmic ray (CR) stellar feedback prescriptions. However, numerical schemes of CR transport are still poorly constrained. We explore how the choice of CR transport affects the multiphase structure of the simulated CGM. We implement anisotropic CR physics in the astrophysical simulation code Enzo and simulate a suite of isolated disk galaxies with varying prescriptions for CR transport: isotropic diffusion, anisotropic diffusion, and streaming. We find that all three transport mechanisms result in strong, metal-rich outflows but differ in the temperature and ionization structure of their CGM. Isotropic diffusion results in a spatially uniform, warm CGM that underpredicts the column densities of low ions. Anisotropic diffusion develops a reservoir of cool gas that extends farther from the galactic center, but disperses rapidly with distance. CR streaming projects cool gas out to radii of 200 kpc, supporting a truly multiphase medium. In addition, we find that streaming is less sensitive to changes in constant parameter values like the CR injection fraction, transport velocity, and resolution than diffusion. We conclude that CR streaming is a more robust implementation of CR transport and motivates the need for detailed parameter studies of CR transport.
Delta-matroids and Vassiliev invariants

Vassiliev (finite type) invariants of knots can be described in terms of weight systems. These are functions on chord diagrams satisfying so-called 4-term relations. In the study of the sl2 weight system, it was shown that its value on a chord diagram depends on the intersection graph of the diagram rather than on the diagram itself. Moreover, it was shown that the value of this weight system on an intersection graph depends on the cy- cle matroid of the graph rather than on the graph itself. This result arose the question whether there is a natural way to introduce a 4-term relation on the space spanned by matroids, similar to the one for graphs. It happened however that the answer is negative: there are graphs having isomorphic cycle matroids such that applying the "second Vassiliev move" to a pair of corresponding vertices a;b of the graphs we obtain two graphs with nonisomorphic matroids. The goal of the present paper is to show that the situation is different for binary delta-matroids: one can define both the first and the second Vassiliev moves for binary delta-matroids and introduce a 4-term relation for them in such a way that the mapping taking a chord diagram to its delta-matroid respects the corresponding 4-term relations. Moreover, this mapping admits a natural extension to chord diagrams on several circles, which correspond to singular links. Delta-matroids were introduced by A. Bouchet for the purpose of studying embedded graphs, whence their relationship with (multiloop) chord diagrams is by no means unexpected. Some evidence for the existence of such a relationship can be found, for example, the Tutte polynomial for embedded graphs has been introduced. It was shown that this polynomial depends on the delta-matroid of the embedded graph rather than the graph itself and satises the Vassilev 4-term relation.
Conserved charges in (Lovelock) gravity in first order formalism

We derive conserved charges as quasilocal Hamiltonians by covariant phase space methods for a class of geometric Lagrangians that can be written in terms of the spin connection, the vielbein, and possibly other tensorial form fields, allowing also for nonzero torsion. We then recalculate certain known results and derive some new ones in three to six dimensions hopefully enlightening certain aspects of all of them. The quasilocal energy is defined in terms of the metric and not its first derivatives, requiring 'regularization' for convergence in most cases. Counterterms consistent with Dirichlet boundary conditions in first order formalism are shown to be an efficient way to remove divergencies and derive the values of conserved charges, the clear-cut application being metrics with anti-de Sitter (or de Sitter) asymptotics. The emerging scheme is: all is required to remove the divergencies of a Lovelock gravity is a boundary Lovelock gravity.
THICK ACCRETION DISK MODEL FOR ULTRALUMINOUS SUPERSOFT SOURCES

We propose a geometrically thick, super-Eddington accretion disk model, where an optically thick wind is not necessary, to understand ultraluminous supersoft sources (ULSs). For high mass accretion rates M ˙ ≳ 30 M ˙ Edd ? > and not small inclination angles θ ≳ 25 ° ? > , where M ˙ Edd ? > is the Eddington accretion rate, the hard photons from the hot inner region may be shaded by the geometrically thick inner disk, and therefore only the soft photons from the outer thin disk and the outer photosphere of the thick disk can reach the observer. Our model can naturally explain the approximate relation between the typical thermal radius and the thermal temperature, R bb ∝ T bb − 2 ? > . Moreover, the thick disk model can unify ULSs and normal ultraluminous X-ray sources, where the different observational characteristics are probably related to the inclination angle and the mass accretion rate. By comparing our model with the optically thick outflow model, we find that a lower mass accretion rate is required in our model.
The Swarm Telescope Concept

As telescope facilities become increasingly more capable, they also become increasingly complex and require additional resources to operate. This is particularly true for the current and future generations of “software defined telescopes” that can support a variety of observing programs simultaneously, either through commensal observations or through support for multiple pointing centers as in the case of dipole arrays or dishes equipped with phased array feeds. At the same time, many current and future facilities are also distributed over large geographic areas, making monitoring and maintenance more difficult and costly. For these reasons, we have developed a new paradigm for telescope operations called the “swarm telescope” that breaks large, single facilities into smaller groups of independent systems that can collaboratively work together to function as a single facility but with much less operational overhead. In this paper, we outline the swarm telescope concept and an example of its implementation at the Long Wavelength Array. We also discuss potential advantages of using this approach for other facilities, in particular the Next Generation Very Large Array.
Does the three site Higgsless model survive the electroweak precision tests at loop

We complete the list of one-loop renormalization group equations and matching conditions relevant for the computation of the electroweak precision parameters $S$ and $T$ in the three site Higgsless model. We obtain one-loop formulas for $S$ and $T$ expressed in terms of physical observables such as the Kaluza-Klein (KK) gauge boson mass ${M}_{{W}^{\ensuremath{'}}}$, the KK fermion mass $M$, and the KK gauge boson (${W}^{\ensuremath{'}}$) couplings with light quarks and leptons ${g}_{{W}^{\ensuremath{'}}ff}$. It is shown that these physical observables, ${M}_{{W}^{\ensuremath{'}}}$, $M$, and ${g}_{{W}^{\ensuremath{'}}ff}$ are severely constrained by the electroweak precision data. Unlike the tree level analysis on the ideally delocalized fermion, we find that perfect fermiophobity of ${W}^{\ensuremath{'}}$ is ruled out by the precision data. We also study the cutoff dependence of our analysis. Although the model is nonrenormalizable, the dependence on the cutoff parameter $\ensuremath{\Lambda}$ is shown to be nonsignificant.
Widening Disparity and its Suppression in a Stochastic Replicator Model

Winner-take-all phenomena are observed in various competitive systems. We find similar phenomena in replicator models with randomly fluctuating growth rates. The disparity between winners and losers increases indefinitely, even if all elements are statistically equivalent. A lognormal distribution describes well the nonstationary time evolution. If a nonlinear load corresponding to progressive taxation is introduced, a stationary distribution is obtained and disparity widening is suppressed.
Seyfert galaxies that are undergoing merging but appear non-interacting

We present new broad-band optical images of some merging Seyfert galaxies that were earlier considered to be non-interacting objects. In our deep images obtained at the Russian 6-m telescope we have detected elongated tidal envelopes belonging to satellites debris with a surface R-band brightness about 25-26.5 mag arcsec ―2 . These structures are invisible in Sloan Digital Sky Survey (SDSS) pictures because of their photometric limit. We found that 35 per cent of the sample of isolated galaxies has undergone merging during the last 0.5-1 Gyr. Our results suggest that statistical studies based on popular imaging surveys (SDSS or Second Palomar Observatory Sky Survey (POSS-II)) can lead to underestimation of the fraction of minor mergers among galaxies with active nuclei (AGN). This fact impacts on statistics and must be taken into consideration when finding a connection between minor/major merging or interactions and nucleus activity.
EXTENDED UNCERTAINTY PRINCIPLE AND THE GEOMETRY OF (ANTI)-DE SITTER SPACE

It has been proposed that on (anti)-de Sitter background, the Heisenberg uncertainty principle should be modified by the introduction of a term proportional to the cosmological constant. We show that this modification of the uncertainty principle can be derived straightforwardly from the geometric properties of (anti)-de Sitter spacetime. We also discuss the connection between the so-called extended generalized uncertainty principle and triply special relativity.
GALACTIC WINDS DRIVEN BY ISOTROPIC AND ANISOTROPIC COSMIC-RAY DIFFUSION IN DISK GALAXIES

The physics of cosmic rays (CRs) is a promising candidate for explaining the driving of galactic winds and outflows. Recent galaxy formation simulations have demonstrated the need for active CR transport either in the form of diffusion or streaming to successfully launch winds in galaxies. However, due to computational limitations, most previous simulations have modeled CR transport isotropically. Here, we discuss high-resolution simulations of isolated disk galaxies in a 1011 M⊙ halo with the moving-mesh code Arepo that include injection of CRs from supernovae, advective transport, CR cooling, and CR transport through isotropic or anisotropic diffusion. We show that either mode of diffusion leads to the formation of strong bipolar outflows. However, they develop significantly later in the simulation with anisotropic diffusion compared to the simulation with isotropic diffusion. Moreover, we find that isotropic diffusion allows most of the CRs to quickly diffuse out of the disk, while in the simulation with anisotropic diffusion, most CRs remain in the disk once the magnetic field becomes dominated by its azimuthal component, which occurs after ∼300 Myr. This has important consequences for the gas dynamics in the disk. In particular, we show that isotropic diffusion strongly suppresses the amplification of the magnetic field in the disk compared to anisotropic or no diffusion models. We therefore conclude that reliable simulations which include CR transport inevitably need to account for anisotropic diffusion.