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High-resolution ALMA and HST imaging of κCrB: a broad debris disc around a post-main-sequence star with low-mass companions
No full textκCrB is an ∼2.5 Gyr old K1 sub-giant star, with an eccentric exo-Jupiter at ∼2.8 au and a debris disc at tens of au. We present ALMA (Atacama Large Millimetre/submillimetre Array) Band 6 (1.3 mm) and Hubble Space Telescope scattered light (0.6μm) images, demonstrating κCrB’s broad debris disc, covering an extent 50−180au in the millimetre (peaking at 110 au), and 51−280 au in scattered light (peaking at 73 au). By modelling the millimetre emission, we estimate the dust mass as ∼0.016 M_⊕, and constrain lower-limit planetesimal sizes as D_(max) ≳ 1 km and the planetesimal belt mass as M_(disc) ≳ 1 M_⊕. We constrain the properties of an outer body causing a linear trend in 17 yr of radial velocity data to have a semimajor axis 8–66 au and a mass 0.4−120 M_(Jup). There is a large inner cavity seen in the millimetre emission, which we show is consistent with carving by such an outer massive companion with a string of lower mass planets. Our scattered light modelling shows that the dust must have a high anisotropic scattering factor (g ∼ 0.8–0.9) but an inclination (i ∼ 30°–40°) that is inferred to be significantly lower than the i ∼ 61° millimetre inclination. The origin of such a discrepancy is unclear, but could be caused by a misalignment in the micrometre- and millimetre-sized dust. We place an upper limit on the CO gas mass of M_(CO) < (4.2−13) × 10⁻⁷ M_⊕, and show this to be consistent with levels expected from planetesimal collisions, or from CO-ice sublimation as κCrB begins its giant branch ascent
Early Results from GLASS-JWST. I: Confirmation of Lensed z ≥ 7 Lyman-break Galaxies behind the Abell 2744 Cluster with NIRISS
No full textWe present the first search for z ≥ 7, continuum-confirmed Lyman break sources with NIRISS/WFS spectroscopy over the Abell 2744 Frontier Fields cluster, as part of the GLASS-JWST-ERS survey. With ∼15 hr of preimaging and multiangle grism exposures in the F115W, F150W, and F200W filters, we describe the general data handling (i.e., reduction, cleaning, modeling, and extraction processes) and analysis for the GLASS-JWST survey. We showcase the power of JWST to peer deep into reionization, when most intergalactic hydrogen is neutral, by confirming two galaxies at z = 8.04 ± 0.15 and z = 7.90 ± 0.13 by means of their Lyman breaks. Fainter continuum spectra are observed in both the F150W and F200W bands, indicative of blue (−1.69 and −1.33) UV slopes and moderately bright absolute magnitudes (−20.37 and −19.68 mag). We do not detect strong Lyα in either galaxy, but do observe tentative (∼2.7–3.8σ) He ɪɪλ1640 Å, O ɪɪɪ]λλ1661,1666 Å, and N ɪɪɪ]λλ1747,1749 Å line emission in one, suggestive of low-metallicity, star-forming systems with possible nonthermal contributions. These novel observations provide a first look at the extraordinary potential of JWST/NIRISS for confirming representative samples of bright z ≥ 7 sources in the absence of strong emission lines, and gain unprecedented insight into their contributions toward cosmic reionization
Frobenius Allowable Gaps of Generalized Numerical Semigroups
No full textA generalized numerical semigroup is a submonoid S of ℕᵈ for which the complement ℕᵈ\S is finite. The points in the complement ℕᵈ\S are called gaps. A gap F is considered Frobenius allowable if there is some relaxed monomial ordering on ℕᵈ with respect to which F is the largest gap. We characterize the Frobenius allowable gaps of a generalized numerical semigroup. A generalized numerical semigroup that has only one maximal gap under the natural partial ordering of ℕᵈ is called a Frobenius generalized numerical semigroup. We show that Frobenius generalized numerical semigroups are precisely those whose Frobenius gap does not depend on the relaxed monomial ordering. We estimate the number of Frobenius generalized numerical semigroup with a given Frobenius gap F = (F^(1), . . . , F^(d)) ∈ ℕᵈ and show that it is close to √3^[(F^(1) + 1) . . . (F^(d) + 1)] for large d. We define notions of quasi-irreducibility and quasi-symmetry for generalized numerical semigroups. While in the case of d = 1 these notions coincide with irreducibility and symmetry, they are distinct in higher dimensions
Simulation of Interaction-Induced Chiral Topological Dynamics on a Digital Quantum Computer
No full textChiral edge states are highly sought after as paradigmatic topological states relevant to both quantum information processing and dissipationless electron transport. Using superconducting transmon-based quantum computers, we demonstrate chiral topological propagation that is induced by suitably designed interactions, instead of flux or spin-orbit coupling. Also different from conventional 2D realizations, our effective Chern lattice is implemented on a much smaller equivalent 1D spin chain, with sequences of entangling gates encapsulating the required time-reversal breaking. By taking advantage of the quantum nature of the platform, we circumvented difficulties from the limited qubit number and gate fidelity in present-day noisy intermediate-scale quantum era quantum computers, paving the way for the quantum simulation of more sophisticated topological states on very rapidly developing quantum hardware
Topological frequency conversion in Weyl semimetals
No full textWe theoretically predict a working principle for optical amplification, based on Weyl semimetals: When a Weyl semimetal is suitably irradiated at two frequencies, electrons close to the Weyl points convert energy between the frequencies through the mechanism of topological frequency conversion from [Martin et al., Phys. Rev. X 7, 041008 (2017)]. Each electron converts energy at a quantized rate given by an integer multiple of Planck's constant multiplied by the product of the two frequencies. In simulations, we show that optimal, but feasible band structures, can support topological frequency conversion in the “THz gap” at intensities down to 2 W/mm²; the gain from the effect can exceed the dissipative loss when the frequencies are larger than the relaxation time of the system. Topological frequency conversion forms a paradigm for optical amplification, which further extends Weyl semimetals' promise for technological applications
Polarization constraints on the X-ray corona in Seyfert Galaxies: MCG-05-23-16
No full textWe report on the first observation of a radio-quiet active galactic nucleus (AGN) in polarized X-rays: the Seyfert 1.9 galaxy MCG-05-23-16. This source was pointed at with the Imaging X-ray Polarimetry Explorer (IXPE) starting on 2022 May 14 for a net observing time of 486 ks, simultaneously with XMM-Newton (58 ks) and NuSTAR (83 ks). A polarization degree Π smaller than 4.7 per cent (at the 99 per cent confidence level) is derived in the 2–8 keV energy range, where emission is dominated by the primary component ascribed to the hot corona. The broad-band spectrum, inferred from a simultaneous fit to the IXPE, NuSTAR, and XMM-Newton data, is well reproduced by a power law with photon index Γ = 1.85 ± 0.01 and a high-energy cutoff E_C = 120 ± 15 keV. A comparison with Monte Carlo simulations shows that a lamp-post and a conical geometry of the corona are consistent with the observed upper limit, a slab geometry is allowed only if the inclination angle of the system is less than 50°
Rapid extraction of propeller geometry using photogrammetry
No full textAs small Uninhabited Aerial Vehicles (sUAS) increase in popularity, computational analysis is increasingly being used to model and improve their performance. However, although propeller performance is one of the primary elements in modelling an aircraft, most manufacturers of propellers for this size of vehicle do not publish geometric information for the propeller. The lack of available geometric data makes simulation of propeller aerodynamics challenging. While techniques exist to accurately extract the 3D geometry of a propeller, these methods are often very expensive, time-consuming, or labor intensive. Additionally, typical 3D scanning techniques produce a 3D mesh that is not useful for techniques such as Blade Element Theory (BET), which rely on knowledge of the 2D cross sections along the propeller span. This paper describes a novel workflow to produce point clouds using readily available photo equipment and software and subsequently extract airfoil and propeller blade parameters at specified stations along the propeller span. The described process can be done with little theoretical knowledge of photogrammetry and with minimal human input. The propeller geometry generated is compared against results of established methods of geometry extraction and good agreement is shown
Explicit Polarization in Coarse-Grained Simulations of Ionomer Melts
No full textThe structure and morphology of ionic aggregates in ionomer melts significantly influence their ion transport properties. Understanding the underlying mechanisms and relevant time scales of ion transport can facilitate design of viable ionomer materials as single-ion conductors for energy applications. Previous studies have characterized the ionic aggregate structure, morphology, and dynamics using non-polarizable coarse-grained molecular dynamics (CGMD) simulations. In this work, we examine the role of polarization in ionomer melts by explicitly incorporating Drude oscillators in CGMD simulations. We systematically study the structure and dynamics of pendant ionomers, focusing on the comparison to non-polarizable systems. Polarization within the ion clusters leads to less overall ion structuring. On the aggregate scale, less ion structuring yields smaller ionic aggregates. The extent to which the clusters are smaller delicately depends on the strength of the electrostatic interactions (the dielectric constant). Under certain conditions, we find that the time scale for free counterion diffusion does not depend on the morphology, unlike that in a non-polarizable model
Pomite and pseudopomite, two new carbonate-encapsulating mixed-valence polyoxovanadate minerals
No full textPomite (IMA2021-063), ideally Ca₃[V⁴⁺₅V⁵⁺₁₀O₃₇(CO₃)]·37H₂O, and pseudopomite (IMA2021-064), ideally Ca₃.₅[V⁴⁺₆V⁵⁺₉O₃₇(CO₃)]·32H₂O, are two new polyoxometalate minerals from the Blue Streak mine, Bull Canyon, Montrose County, Colorado, U.S.A. Pomite properties: striated blades up to ~1 mm long; very dark green-blue color; green-blue streak; vitreous luster; brittle; Mohs hardness ≈2; irregular, splintery fracture; good cleavages on {010} and {001}; 2.19(2) g/cm⁻³ density; refractive indices in the vicinity of 1.70; weakly birefringent with little or no pleochroism. Pseudopomite properties: striated prisms and blades up to ~1 mm; very dark blue-green color; blue-green streak; vitreous luster; brittle; Mohs hardness ≈2; curved, irregular fracture; probably two fair cleavages, {100} and {001}; 2.40(2) g/cm⁻³ density; refractive indices in the vicinity of 1.72; no discernable birefringence or pleochroism. Electron microprobe analyses provided the empirical formulas Ca₃.₁₁[V⁴⁺₅.₂₃V⁵⁺₉.₇₇O₃₇(CO₃)]·37H₂O and Ca₃.₄₉[V⁴⁺₅.₉₈V⁵⁺₉.₀₂O₃₇(CO₃)]·29H₂O for pomite and pseudopomite, respectively. Pomite is triclinic, P1̅, with a = 12.3668(10), b = 12.9692(12), c = 22.068(2) Å, α = 99.038(7), β = 95.689(7), γ = 103.249(7)°, V = 3368.7(5) ų, and Z = 2. Pseudopomite is triclinic, P1̅, with a = 12.2910(18), b = 12.6205(15), c = 20.917(3) Å, α = 77.381(6), β = 85.965(5), γ = 64.367(7)°, V = 2853.6(7) ų, and Z = 2. The crystal structures of both minerals (pomite, R₁ = 0.103; pseudopomite, R₁ = 0.116) contain a novel [V⁴⁺ₓV⁵⁺₁₅₋ₓO₃₇(CO₃)]⁽¹⁺ˣ⁾⁻ heteropolyanion, which is unique in natural and synthetic materials but has similarities to the [V⁴⁺₈V⁵⁺₇O₃₆(CO₃)]⁷⁻ and [H₈V⁴⁺₁₅O₃₆(CO₃)]⁶⁻ heteropolyanions reported in synthetic phases
Optimal and Fast Confidence Intervals for Hypergeometric Successes
No full textWe present an efficient method of calculating exact confidence intervals for the hypergeometric parameter representing the number of “successes,” or “special items,” in the population. The method inverts minimum-width acceptance intervals after shifting them to make their endpoints nondecreasing while preserving their level. The resulting set of confidence intervals achieves minimum possible average size, and even in comparison with confidence sets not required to be intervals it attains the minimum possible cardinality most of the time, and always within 1. The method compares favorably with existing methods not only in the size of the intervals but also in the time required to compute them. The available R package hyperMCI implements the proposed method