cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
An ESPRESSO view of HD 189733 system. Broadband transmission spectrum, differential rotation, and system architecture
Creators: name: Cristo, E.
name: Borges, E. Esparza
name: Santos, N. C.
name: Demangeon, O.
name: Palle, E.
name: Psaridi, A.
name: Bourrier, V.
name: Faria, J. P.
name: Allart, R.
name: Silva, T. Azevedo
name: Borsa, F.
name: Alibert, Y.
name: Figueira, P.
name: Hernández, J. I. González
name: Lendl, M.
name: Lillo-Box, J.
name: Curto, G. Lo
name: Di Marcantonio, P.
name: Martins, C. J. A. P.
name: Nunes, N. J.
name: Pepe, F.
name: Seidel, J. V.
name: Sousa, S. G.
name: Sozzetti, A.
name: Stangret, M.
name: Mascareño, A. Suárez
name: Tabernero, H. M.
name: Osorio, M. R. Zapatero
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The development of state-of-the-art spectrographs has ushered in a new era in the detection and characterization of exoplanetary systems. Our objective is to utilize the high-resolution and precision capabilities of the ESPRESSO instrument to detect and measure the broad-band transmission spectrum of HD 189733b's atmosphere. Additionally, we aim to employ an improved Rossiter-McLaughlin model to derive properties related to the velocity fields of the stellar surface and to constrain the orbital architecture.
 Our results demonstrate a high degree of precision in fitting the observed radial velocities during transit using the improved modeling of the Rossiter-McLaughlin effect. We tentatively detect the effect of differential rotation with a confidence level of $93.4 \%$ when considering a rotation period within the photometric literature values, and $99.6\%$ for a broader range of rotation periods. For the former, the amplitude of differential rotation ratio suggests an equatorial rotation period of $11.45\pm 0.09$ days and a polar period of $14.9\pm 2$. The addition of differential rotation breaks the latitudinal symmetry, enabling us to measure the true spin-orbit angle $ ψ\approx 13.6 \pm 6.9 ^\circ$ and the stellar inclination axis angle $ i_{\star} \approx 71.87 ^{+6.91^\circ}_{-5.55^\circ}$. Moreover, we determine a sub-solar amplitude of the convective blueshift velocity $V_{CB}$ $\approx$ $-211 ^{+69} _{-61}$ m$\,$s$ ^{-1}$, which falls within the expected range for a K-dwarf host star and is compatible with both runs.
 Finally, we successfully retrieved the transmission spectrum of HD 189733b from the high-resolution ESPRESSO data. We observe a significant decrease in radius with increasing wavelength, consistent with the phenomenon of super-Rayleigh scattering.
Anisotropic hybridization probed by polarization dependent x-ray absorption spectroscopy in VI3 van der Waals Mott ferromagnet
Creators: name: Sant, R.
name: De Vita, A.
name: Polewczyk, V.
name: Pierantozzi, G.
name: Mazzola, F.
name: Vinai, G.
name: van der Laan, G.
name: Panaccione, G.
name: Brookes, N. B.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Polarization dependent x-ray absorption spectroscopy was used to study the magnetic ground state and the orbital occupation in bulk-phase VI$_3$ van der Waals crystals below and above the ferromagnetic and structural transitions. X-ray natural linear dichroism and X-ray magnetic circular dichroism spectra acquired at the V $L_{2,3}$ edges are compared against multiplet cluster calculations within the frame of the ligand field theory to quantify the intra-atomic electronic interactions at play and evaluate the effects of symmetry reduction occurring in a trigonally distorted VI$_6$ unit. We observed a non zero linear dichroism proving the presence of an anisotropic charge density distribution around the V$^{3+}$ ion due to the unbalanced hybridization between the Vanadium and the ligand states. Such hybridization acts as an effective trigonal crystal field, slightly lifting the degeneracy of the $t_{2g}^2$ ground state. However, the energy splitting associated to the distortion underestimates the experimental band gap, suggesting that the insulating ground state is stabilized by Mott correlation effects rather than via a Jahn-Teller mechanism. Our results clarify the role of the distortion in VI$_3$ and establish a benchmark for the study of the spectroscopic properties of other van der Waals halides, including emerging 2D materials with mono and few-layers thickness, whose fundamental properties might be altered by reduced dimensions and interface proximity.
Interaction of evanescent particles with an Unruh-DeWitt detector
Creators: name: Colosi, Daniele
name: Oeckl, Robert
name: Zampeli, Adamantia
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We demonstrate that the recently introduced evanescent particles of a massive scalar field can be emitted and absorbed by an Unruh-DeWitt detector. In doing so the particles carry away from or deposit on the detector a quantized amount of energy, in a manner quite analogous to ordinary propagating particles. In contradistinction to propagating particles the amount of energy is less than the mass of the field, but still positive. We develop relevant methods and provide a study of the detector emission spectrum, emission probability and absorption probability involving both propagating and evanescent particles.
description: 42 pages, 11 figures; v2: typos corrected, changed numbering style to match published version
Design and Implementation of Ultra-Wideband Frequency-Domain Chipless RFID Readers
Creators: name: MOHAMMADALI FOROUZANDEH
Publisher: name: Monash University
Year: 2020
Subjects: subject: 100505 Microwave and Millimetrewave Theory and Technology
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: 90699 Electrical and Electronic Engineering not elsewhere classified

description: Development of a compact, low-cost, and high-performance reader for reading the chipless RFID tags is believed to be key for making chipless RFID technology a commercial reality. This dissertation aims at providing a total solution for this real-world technological challenge by overcoming the practical, engineering, scientific, and cost-related issues of the chipless RFID systems. Several UWB passive and active RF components are designed and implemented from scratch, and various novel techniques to improve the performance of the individual components as well as the sub-systems are proposed. Finally, three UWB frequency-domain RFID readers are implemented, and their performances are evaluated.
Mid-IR AGPMs for ELT applications
Creators: name: Carlomagno, Brunella
name: Delacroix, Christian
name: Absil, Olivier
name: Forsberg, Pontus
name: Habraken, Serge
name: Jolivet, Aïssa
name: Karlsson, Mikael
name: Mawet, Dimitri
name: Piron, Pierre
name: Surdej, Jean
name: Catalan, Ernesto Vargas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The mid-infrared region is well suited for exoplanet detection thanks to the reduced contrast between the planet and its host star with respect to the visible and near-infrared wavelength regimes. This contrast may be further improved with Vector Vortex Coronagraphs (VVCs), which allow us to cancel the starlight. One flavour of the VVC is the AGPM (Annular Groove Phase Mask), which adds the interesting properties of subwavelength gratings (achromaticity, robustness) to the already known properties of the VVC. In this paper, we present the optimized designs, as well as the expected performances of mid-IR AGPMs etched onto synthetic diamond substrates, which are considered for the E-ELT/METIS instrument.
description: 8 pages, 5 figures, Proc. of SPIE Vol. 9147 (2014)
3DInvNet: A Deep Learning-Based 3D Ground-Penetrating Radar Data Inversion
Creators: name: Dai, Qiqi
name: Lee, Yee Hui
name: Sun, Hai-Han
name: Ow, Genevieve
name: Yusof, Mohamed Lokman Mohd
name: Yucel, Abdulkadir C.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Signal Processing (eess.SP)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: The reconstruction of the 3D permittivity map from ground-penetrating radar (GPR) data is of great importance for mapping subsurface environments and inspecting underground structural integrity. Traditional iterative 3D reconstruction algorithms suffer from strong non-linearity, ill-posedness, and high computational cost. To tackle these issues, a 3D deep learning scheme, called 3DInvNet, is proposed to reconstruct 3D permittivity maps from GPR C-scans. The proposed scheme leverages a prior 3D convolutional neural network with a feature attention mechanism to suppress the noise in the C-scans due to subsurface heterogeneous soil environments. Then a 3D U-shaped encoder-decoder network with multi-scale feature aggregation modules is designed to establish the optimal inverse mapping from the denoised C-scans to 3D permittivity maps. Furthermore, a three-step separate learning strategy is employed to pre-train and fine-tune the networks. The proposed scheme is applied to numerical simulation as well as real measurement data. The quantitative and qualitative results show the network capability, generalizability, and robustness in denoising GPR C-scans and reconstructing 3D permittivity maps of subsurface objects.
Lensing Bias to CMB Measurements of Compensated Isocurvature Perturbations
Creators: name: Heinrich, Chen He
name: Grin, Daniel
name: Hu, Wayne
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Compensated isocurvature perturbations (CIPs) are modes in which the baryon and dark matter density fluctuations cancel. They arise in the curvaton scenario as well as some models of baryogenesis. While they leave no observable effects on the cosmic microwave background (CMB) at linear order, they do spatially modulate two-point CMB statistics and can be reconstructed in a manner similar to gravitational lensing. Due to the similarity between the effects of CMB lensing and CIPs, lensing contributes nearly Gaussian random noise to the CIP estimator that approximately doubles the reconstruction noise power. Additionally, the cross correlation between lensing and the integrated Sachs-Wolfe (ISW) effect generates a correlation between the CIP estimator and the temperature field even in the absence of a correlated CIP signal. For cosmic-variance limited temperature measurements out to multipoles $l \leq 2500$, subtracting a fixed lensing bias degrades the detection threshold for CIPs by a factor of $1.3$, whether or not they are correlated with the adiabatic mode.
description: 10 pages, 12 figures; one of the authors Chen He Heinrich was previously known as Chen He
New calibrations for abundance determinations in HII regions
Creators: name: Pilyugin, L. S.
name: Grebel, E. K.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Simple relations for deriving the oxygen abundance in HII regions with intensities of the three strong emission lines R_2, R_3, and N_2 (R calibration) or S_2, R_3, and N_2 (S calibration) in their spectra are suggested. A sample of 313 reference HII regions of the counterpart method is used as calibrating data points. Relations for the determination of nitrogen abundances, the R calibration, are also constructed. We find that the oxygen and nitrogen abundances in high-metallicity HII regions can be estimated using the intensities of the two strong lines R_2 and N_2 (or S_2 and N_2 for oxygen) only. The corresponding two-dimensional relations are provided. There are considerable advantages of the suggested calibration relations as compared to the existing ones. First, the oxygen and nitrogen abundances estimated through the suggested calibrations agree with the Te-based abundances within ~0.1 dex over the whole metallicity range, i.e., the relative accuracy of the calibration-based abundances is 0.1 dex. Although we constructed distinct relations for high- and low-metallicity objects, the separation between these two can be simply obtained from the intensity of the N_2 line. Moreover, the applicability ranges of the high- and low-metallicity relations overlap for adjacent metallicities, i.e., the transition zone disappears. Second, the oxygen abundances produced by the two suggested calibrations are in remarkable agreement with each other. In fact, the R-based and S-based oxygen abundances agree within ~0.05 dex in the majority of cases for more than three thousand HII region spectra.
description: 16 pages, 9 figues, accepted to MNRAS
Interplay between electron correlations, magnetic state, and structural confinement in LaNiO3 ultrathin films
Creators: name: Vambold, N. O.
name: Sazhaev, G. A.
name: Leonov, I. V.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report a theoretical study of the effects of electron correlations and structural confinement on the electronic properties and magnetic state of LaNiO3 (LNO) thin films epitaxially deposited on the (001) LaAlO3 (LAO) substrate. Using the DFT+U method we compute the electronic band structure, magnetic properties, and phase stability of the 1.5 unit-cell-thick NiO2-terminated LNO thin films. Our results reveal complex diversity of the electronic states caused by the effects of structural confinement, interfacial charge transfer and electronic correlations. Our calculations suggest the appearance of in-plane (110) charge disproportionation of the Ni ions in the interface NiO2 layer of the antiferromagnetically ordered LNO thin films. Moreover, the electronic states of both the AFM and FM LNO/LAO show a large orbital polarization of the Ni ions in the surface NiO2 layers. We propose the crucial importance of oxygen defects to explain the metal-to-insulator phase transition experimentally observed in a few-unit-cell-thick LNO/LAO thin films.
description: 6 pages, 7 figures
HSC-CLAUDS survey: The star formation rate functions since z ~ 2 and comparison with hydrodynamical simulations
Creators: name: Picouet, V.
name: Arnouts, S.
name: Floch, E. Le
name: Moutard, T.
name: Kraljic, K.
name: Ilbert, O.
name: Sawicki, M.
name: Desprez, G.
name: Laigle, C.
name: Schiminovich, D.
name: de la Torre, S.
name: Gwyn, S.
name: McCracken, H. J.
name: Dubois, Y.
name: Davé, R.
name: Toft, S.
name: Weaver, J. R.
name: Shuntov, M.
name: Kauffmann, O. B.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Star formation rate functions (SFRFs) give an instantaneous view of the distribution of star formation rates (SFRs) in galaxies at different epochs. They are a complementary and more stringent test for models than the galaxy stellar mass function, which gives an integrated view of the past star formation activity. However, the exploration of SFRFs has been limited thus far due to difficulties in assessing the SFR from observed quantities and probing the SFRF over a wide range of SFRs. We overcome these limitations thanks to an original method that predicts the infrared luminosity from the rest-frame UV/optical color of a galaxy and then its SFR over a wide range of stellar masses and redshifts. We applied this technique to the deep imaging survey HSC-CLAUDS combined with near-infrared and UV photometry. We provide the first SFR functions with reliable measurements in the high- and low-SFR regimes up to $z=2$ and compare our results with previous observations and four state-of-the-art hydrodynamical simulations.
description: 29 pages, 19 figures
nIFTy Galaxy Cluster simulations IV: Quantifying the Influence of Baryons on Halo Properties
Creators: name: Cui, Weiguang
name: Power, Chris
name: Knebe, Alexander
name: Kay, Scott T.
name: Sembolini, Federico
name: Elahi, Pascal J.
name: Yepes, Gustavo
name: Pearce, Frazer
name: Cunnama, Daniel
name: Beck, Alexander M.
name: Vecchia, Claudio Dalla
name: Davé, Romeel
name: February, Sean
name: Huang, Shuiyao
name: Hobbs, Alex
name: Katz, Neal
name: McCarthy, Ian G.
name: Murante, Giuseppe
name: Perret, Valentin
name: Puchwein, Ewald
name: Read, Justin I.
name: Saro, Alexandro
name: Teyssier, Romain
name: Thacker, Robert J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Building on the initial results of the nIFTy simulated galaxy cluster comparison, we compare and contrast the impact of baryonic physics with a single massive galaxy cluster, run with 11 state-of-the-art codes, spanning adaptive mesh, moving mesh, classic and modern SPH approaches. For each code represented we have a dark matter only (DM) and non-radiative (NR) version of the cluster, as well as a full physics (FP) version for a subset of the codes. We compare both radial mass and kinematic profiles, as well as global measures of the cluster (e.g. concentration, spin, shape), in the NR and FP runs with that in the DM runs. Our analysis reveals good consistency (<= 20%) between global properties of the cluster predicted by different codes when integrated quantities are measured within the virial radius R200. However, we see larger differences for quantities within R2500, especially in the FP runs. The radial profiles reveal a diversity, especially in the cluster centre, between the NR runs, which can be understood straightforwardly from the division of codes into classic SPH and non-classic SPH (including the modern SPH, adaptive and moving mesh codes); and between the FP runs, which can also be understood broadly from the division of codes into those that include AGN feedback and those that do not. The variation with respect to the median is much larger in the FP runs with different baryonic physics prescriptions than in the NR runs with different hydrodynamics solvers.
description: 24 pages, 13 figures, MNRAS submitted
Understanding Sun-as-a-star variability of solar Balmer lines
Creators: name: Criscuoli, Serena
name: Marchenko, Sergey
name: DeLand, Matthew
name: Choudhary, Debi
name: Kopp, Greg
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Precise, high-cadence, long-term records of stellar spectral variability at different temporal scales lead to better understanding of a wide variety of phenomena including stellar atmospheres and dynamos, convective motions, and rotational periods. Here, we investigate the variability of solar Balmer lines (H-$α$, -$β$, -$γ$, -$δ$) observed by space-borne radiometers (OSIRIS, SCIAMACHY, OMI, and GOME-2), combining these precise, long-term observations with high-resolution data from the ground-based NSO/ISS spectrograph. We relate the detected variability to the appearance of magnetic features on the solar disk. We find that on solar-rotational timescales (about 1 month), the Balmer line activity indices (defined as line-core to line-wing ratios) closely follow variations in the total solar irradiance (which is predominantly photospheric), thus frequently (specifically, during passages of sunspot groups) deviating from behavior of activity indices that track chromospheric activity levels. On longer timescales, the correlation with chromospheric indices increases, with periods of low- or even anti-correlation found at intermediate timescales. Comparison of these observations with estimates from semi-empirical irradiance reconstructions helps quantify the contributions of different magnetic and quiet features. We conclude that both the lower sensitivity to network and in part the higher sensitivity to filaments and prominences, may result in complex, time-dependent relationships between Balmer and other chromospheric indices observed for the Sun and solar-like stars. The fact that core and wings contribute in similar manner to the variability, and current knowledge of Balmer-lines formation in stellar atmospheres, support the notion that Balmer lines core-to-wing ratios indices behave more like photospheric rather than chromospheric indices.
description: Accepted for publication on ApJ on April 28, 2023
The spark of synchronization in heterogeneous networks of chaotic maps
Creators: name: Montalban, Antonio
name: Corder, Rodrigo M.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Adaptation and Self-Organizing Systems (nlin.AO)
subject: Chaotic Dynamics (nlin.CD)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We investigate the emergence of synchronization in heterogeneous networks of chaotic maps. Our findings reveal that a small cluster of highly connected maps is responsible for triggering the spark of synchronization. After the spark, the synchronized cluster grows in size and progressively moves to less connected maps, eventually reaching a cluster that may remain synchronized over time. We explore how the shape of the network's degree distribution affects the onset of synchronization and derive an expression based on the network's construction that determines the expected time for a network to synchronize. Understanding how the network structure affects the spark of synchronization is particularly important for the control and design of more robust systems that require some level of coherence between a subset of units for better functioning. Numerical simulations in finite-sized networks are consistent with this analysis.
Reactions of Acetonitrile with Trapped, Translationally Cold Acetylene Cations
Creators: name: Krohn, O. A.
name: Catani, K. J.
name: Sundar, S. P.
name: Greenberg, J.
name: da Silva, G.
name: Lewandowski, H. J.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: The reaction of the acetylene cation (C2H2+) with acetonitrile (CH3CN) is measured in a linear Paul ion trap coupled to a time-of-flight mass spectrometer. C2H2+ and CH3CN are both noted for their astrochemical abundance and predicted relevance for understanding prebiotic chemistry. The observed primary products are c-C3H3+, C3H4+ and C2NH3+. The latter two products react with excess CH3CN to form the secondary product C2NH4+, protonated acetonitrile. The molecular formula of these ionic products can be verified with the aid of isotope substitution via deuteration of the reactants. Primary product reaction pathways and thermodynamics are investigated with quantum chemical calculations and demonstrate exothermic pathways to two isomers of C2NH3+, two isomers of C3H4+, and the cyclopropenyl cation c-C3H3+. This study deepens our understanding of the dynamics and products of a pertinent ion-molecule reaction between two astrochemically abundant molecules in conditions that mimic those of the interstellar medium.
Magnetic reconnection as an erosion mechanism for magnetic switchbacks
Creators: name: Suen, G. H. H.
name: Owen, C. J.
name: Verscharen, D.
name: Horbury, T. S.
name: Louarn, P.
name: De Marco, R.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Space Physics (physics.space-ph)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: Magnetic switchbacks are localised polarity reversals in the radial component of the heliospheric magnetic field. Observations from Parker Solar Probe (PSP) have shown that they are a prevalent feature of the near-Sun solar wind. However, observations of switchbacks at 1 au and beyond are less frequent, suggesting that these structures evolve and potentially erode through yet-to-be identified mechanisms as they propagate away from the Sun. We analyse magnetic field and plasma data from the Magnetometer and Solar Wind Analyser instruments aboard Solar Orbiter between 10 August and 30 August 2021. During this period, the spacecraft was 0.6 to 0.7 au from the Sun. We identify three instances of reconnection occurring at the trailing edge of magnetic switchbacks, with properties consistent with existing models describing reconnection in the solar wind. Using hodographs and Walen analysis methods, we test for rotational discontinuities (RDs) in the magnetic field and reconnection-associated outflows at the boundaries of the identified switchback structures. Based on these observations, we propose a scenario through which reconnection can erode a switchback and we estimate the timescales over which this occurs. For our events, the erosion timescales are much shorter than the expansion timescale and thus, the complete erosion of all three observed switchbacks would occur well before they reach 1 au. Furthermore, we find that the spatial scale of these switchbacks would be considerably larger than is typically observed in the inner heliosphere if the onset of reconnection occurs close to the Sun. Hence, our results suggest that the onset of reconnection must occur during transport in the solar wind in our cases. These results suggest that reconnection can contribute to the erosion of switchbacks and may explain the relative rarity of switchback observations at 1 au.
description: Accepted for publication in Astronomy & Astrophysics 05/05/2023
Imaging an Event Horizon: Mitigation of Source Variability of Sagittarius A*
Creators: name: Lu, Ru-Sen
name: Roelofs, Freek
name: Fish, Vincent L.
name: Shiokawa, Hotaka
name: Doeleman, Sheperd S.
name: Gammie, Charles F.
name: Falcke, Heino
name: Krichbaum, Thomas P.
name: Zensus, J. Anton
Publisher: name: arXiv
Year: 2015
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The black hole in the center of the Galaxy, associated with the compact source Sagittarius A* (Sgr A*), is predicted to cast a shadow upon the emission of the surrounding plasma flow, which encodes the influence of general relativity in the strong-field regime. The Event Horizon Telescope (EHT) is a Very Long Baseline Interferometry (VLBI) network with a goal of imaging nearby supermassive black holes (in particular Sgr A* and M87) with angular resolution sufficient to observe strong gravity effects near the event horizon. General relativistic magnetohydrodynamic (GRMHD) simulations show that radio emission from Sgr A* exhibits vari- ability on timescales of minutes, much shorter than the duration of a typical VLBI imaging experiment, which usually takes several hours. A changing source structure during the observations, however, violates one of the basic assumptions needed for aperture synthesis in radio interferometry imaging to work. By simulating realistic EHT observations of a model movie of Sgr A*, we demonstrate that an image of the average quiescent emission, featuring the characteristic black hole shadow and photon ring predicted by general relativity, can nonetheless be obtained by observing over multiple days and subsequent processing of the visibilities (scaling, averaging, and smoothing) before imaging. Moreover, it is shown that this procedure can be combined with an existing method to mitigate the effects of interstellar scattering. Taken together, these techniques allow the black hole shadow in the Galactic center to be recovered on the reconstructed image.
description: 10 pages, 12figures, accepted for publication in ApJ
Controlling the Solo12 Quadruped Robot with Deep Reinforcement Learning
Creators: name: Aractingi, Michel
name: Léziart, Pierre-Alexandre
name: Flayols, Thomas
name: Perez, Julien
name: Silander, Tomi
name: Souères, Philippe
Publisher: name: arXiv
Year: 2023
Subjects: subject: Robotics (cs.RO)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Quadruped robots require robust and general locomotion skills to exploit their mobility potential in complex and challenging environments. In this work, we present the first implementation of a robust end-to-end learning-based controller on the Solo12 quadruped. Our method is based on deep reinforcement learning of joint impedance references. The resulting control policies follow a commanded velocity reference while being efficient in its energy consumption, robust and easy to deploy. We detail the learning procedure and method for transfer on the real robot. In our experiments, we show that the Solo12 robot is a suitable open-source platform for research combining learning and control because of the easiness in transferring and deploying learned controllers.
Overcritical Fermi Superfluids
Creators: name: Andreev, A. F.
name: Melnikovsky, L. A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Superfluidity in Fermi systems is not destroyed by a flow exceeding the Landau velocity threshold. The overcritical state acquires normal component even at zero temperature. We explore peculiar hydrodynamics of this system and discover two sound modes, for which the explicit universal dispersion relations are provided.
description: 8 pages, 2 figures
A signaling protocol for service function localization
Creators: name: Femminella, Mauro
name: Reali, Gianluca
name: Valocchi, Dario
Publisher: name: arXiv
Year: 2016
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: Current proposals for combining service functions (SFs) do not address some critical management issues, such as the discovery of SF instances close to IP data paths. This information is crucial for deploying complex services both in large cloud networks, where SFs may be moved or replicated, and in the emerging fog/mobile edge computing systems. For this purpose, in this letter we propose the distributed off-path signaling protocol (OSP). We show the protocol functions and demonstrate its scalability and effectiveness by experimental results.
description: Accepted for publication in IEEE Communications Letters
The Hawking cascades of gravitons from higher-dimensional Schwarzschild black holes
Creators: name: Hod, Shahar
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: It has recently been shown that the Hawking evaporation process of $(3+1)$-dimensional Schwarzschild black holes is characterized by the dimensionless ratio $η\equivτ_{\text{gap}}/τ_{\text{emission}}\gg1$, where $τ_{\text{gap}}$ is the characteristic time gap between the emissions of successive Hawking quanta and $τ_{\text{emission}}$ is the characteristic timescale required for an individual Hawking quantum to be emitted from the Schwarzschild black hole. This strong inequality implies that the Hawking cascade of gravitons from a $(3+1)$-dimensional Schwarzschild black hole is extremely {\it sparse}. In the present paper we explore the semi-classical Hawking evaporation rates of {\it higher}-dimensional Schwarzschild black holes. We find that the dimensionless ratio $η(D)\equiv{τ_{\text{gap}}/{τ_{\text{emission}}}}$, which characterizes the Hawking emission of gravitons from the $(D+1)$-dimensional Schwarzschild black holes, is a {\it decreasing} function of the spacetime dimension. In particular, we show that higher-dimensional Schwarzschild black holes with $D\gtrsim 10$ are characterized by the relation $η(D)<1$. Our results thus imply that, contrary to the $(3+1)$-dimensional case, the characteristic Hawking cascades of gravitons from these higher-dimensional black holes have a {\it continuous} character.
description: 6 pages in Physics Letters B 756, 133 (2016)
Gauge Theory by canonical Transformations
Creators: name: Koenigstein, Adrian
name: Kirsch, Johannes
name: Stoecker, Horst
name: Struckmeier, Juergen
name: Vasak, David
name: Hanauske, Matthias
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Electromagnetism, the strong and the weak interaction are commonly formulated as gauge theories in a Lagrangian description. In this paper we present an alternative formal derivation of U(1)-gauge theory in a manifestly covariant Hamilton formalism. We make use of canonical transformations as our guiding tool to formalize the gauging procedure. The introduction of the gauge field, its transformation behaviour and a dynamical gauge field Lagrangian/Hamiltonian are unavoidable consequences of this formalism, whereas the form of the free gauge Lagrangian/Hamiltonian depends on the selection of the gauge dependence of the canonically conjugate gauge fields.
description: 27 pages
Multiplexing Free-Space Channels using Twisted Light
Creators: name: Rodenburg, Brandon
name: Magaña-Loaiza, Omar S.
name: Mirhosseini, Mohammad
name: Taherirostami, Payam
name: Chen, Changchen
name: Boyd, Robert W.
Publisher: name: arXiv
Year: 2015
Subjects: subject: Quantum Physics (quant-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We experimentally demonstrate an interferometric protocol for multiplexing optical states of light, with potential to become a standard element in free-space communication schemes that utilize light endowed with orbital angular momentum (OAM). We demonstrate multiplexing for odd and even OAM superpositions generated using different sources. In addition, our technique permits one to prepare either coherent superpositions or statistical mixtures of OAM states. We employ state tomography to study the performance of this protocol, and we demonstrate fidelities greater than 0.98.
description: 4 pages, 3 figures
Angular momentum and topological dependence of Kepler's Third Law in the Broucke-Hadjidemetriou-Hénon family of periodic three-body orbits
Creators: name: Janković, Marija R.
name: Dmitrašinović, Veljko
Publisher: name: arXiv
Year: 2016
Subjects: subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences

description: We use 57 recently found topological satellites of Broucke-Hadjidemetriou-Henon's periodic orbits with values of the topological exponent $k$ ranging from $k$ = 3 to $k$ = 58 to plot the angular momentum $L$ as a function of the period $T$, with both $L$ and $T$ rescaled to energy $E=-\frac12$. Upon plotting $L(T/k)$ we find that all our solutions fall on a curve that is virtually indiscernible by naked eye from the $L(T)$ curve for non-satellite solutions. The standard deviation of the satellite data from the sixth-order polynomial fit to the progenitor data is $σ= 0.13$. This regularity supports Henon's 1976 conjecture that the linearly stable Broucke-Hadjidemetriou-Henon orbits are also perpetually, or Kolmogorov-Arnold-Moser stable.
Density domains of a photo-excited electron gas on liquid helium
Creators: name: Monarkha, Yuriy
Publisher: name: arXiv
Year: 2016
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The Coulombic effect on the stability range of the photo-excited electron gas on liquid helium is shown to favor formation of domains of different densities. Domains appear to eliminate or greatly reduce regions with negative conductivity. An analysis of the density domain structure allows explaining remarkable observations reported recently for the photo-excited electron gas.
description: 5 pages, 5 figures
Statistics of Magrathea exoplanets beyond the Main Sequence. Simulating the long-term evolution of circumbinary giant planets with TRES
Creators: name: Columba, Gabriele
name: Danielski, Camilla
name: Dorozsmai, Andris
name: Toonen, Silvia
name: Puertas, Manuel Lopez
Publisher: name: arXiv
Year: 2023
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Notwithstanding the tremendous growth of the exoplanetary field in the last decade, limited attention has been paid to the planets around binary stars. Circumbinary planets (CBPs) have been discovered primarily around Main Sequence (MS) stars. No exoplanet has been found orbiting double white dwarf (DWD) binaries yet. We modelled the long-term evolution of CBPs, throughout the life stages of their hosts, from MS to white dwarf (WD). Our goal is to provide the community with both theoretical constraints on CBPs evolution beyond the MS and the occurrence rates of planet survival. We further developed the publicly available Triple Evolution Simulation (TRES) code, implementing a variety of physical processes affecting substellar bodies. We then used this code to simulate the evolution, up to one Hubble time, of two synthetic populations of circumbinary giant planets. Each population has been generated using different priors for the planetary orbital parameters. In our simulated populations we identified several evolutionary categories, such as survived, merged, and destabilised systems. Our primary focus is those systems where the planet survived the entire system evolution and orbits a DWD binary, which we call "Magrathea" planets. We found that a significant fraction of simulated CBPs survive and become Magratheas. In the absence of multi-planet migration mechanisms, this category of planets is characterised by long orbital periods. Magrathea planets are a natural outcome of triple systems evolution, and they could be relatively common in the Galaxy. They can survive the death of their binary hosts if they orbit far enough to avoid engulfment and instabilities. Our results can ultimately be a reference to orient future observations of this uncharted class of planets and to compare different theoretical models.
description: Accepted for publication on A&A. 17 pages (+7 in the appendix), 8 figures (+9 in the appendix), 3 tables
Spilomicrus myrmecophilus Nixon 1947
Creators: name: Notton, David G.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Diapriidae
Spilomicrus
Spilomicrus myrmecophilus

description: Spilomicrus myrmecophilus Nixon, 1947: 787, figs 1-3.
Valid name
Spilomicrus myrmecophilus Nixon, 1947.
Summary of types
Holotype ♀, BMNH number 9.646, by original designation. Paratypes 3 ♀♀.
Primary type data
Type; 93/ Mauritius / 26.x.1945 / R.Mamet; In nest of Solenopsis/ mameti/ Donis.; Spilomicrus / myrmecophilus/ Nixon/ type ♀, 1947; Pres. by/ Imp. Inst. Ent./ B.M.1947-417.
Type locality
Mauritius, Corps de Garde Mountain.
Remarks
The holotype is on a card point and is entire.
description: Published as part of Notton, David G., 2014, A catalogue of the types of Diapriinae (Hymenoptera, Diapriidae) at the Natural History Museum, London, pp. 1-123 in European Journal of Taxonomy 75 on page 94, DOI: 10.5852/ejt.2014.75, http://zenodo.org/record/3862773
Random number generation using spontaneous symmetry breaking in a Kerr resonator
Creators: name: Quinn, Liam
name: Xu, Gang
name: Xu, Yiqing
name: Li, Zongda
name: Fatome, Julien
name: Murdoch, Stuart G.
name: Coen, Stéphane
name: Erkintalo, Miro
Publisher: name: arXiv
Year: 2023
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We experimentally demonstrate an all-optical random number generator based on spontaneous symmetry breaking in a coherently-driven Kerr resonator. Random bit sequences are generated by repeatedly tuning a control parameter across a symmetry-breaking bifurcation that enacts random selection between two possible steady-states of the system. Experiments are performed in a fibre ring resonator, where the two symmetry-broken steady-states are associated with orthogonal polarization modes. Detrimental biases due to system asymmetries are completely suppressed by leveraging a recently-discovered self-symmetrization phenomenon that ensures the symmetry breaking acts as an unbiased coin toss, with a genuinely random selection between the two available steady-states. We optically generate bits at a rate of over 3~MHz without post-processing and verify their randomness using the National Institute of Standards and Technology and Dieharder statistical test suites.
description: 5 pages, 4 figures
IC 485:a new candidate disk-maser galaxy at $\sim$100 Mpc distance. Milliarcsecond resolution study of the galaxy nucleus and of the $H_{2}O$ megamaser
Creators: name: Ladu, E.
name: Tarchi, A.
name: Castangia, P.
name: Surcis, G.
name: Braatz, J. A.
name: Panessa, F.
name: Pesce, D.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Masers are a unique tool to investigate the emitting gas in the innermost regions of AGNs and to map accretion disks and tori orbiting around supermassive black holes. IC485, which is classified as a LINER or Seyfert galaxy, hosts a bright water maser whose nature is still under debate. Indeed, this might be either a nuclear disk maser, a jet/outflow maser, or even the very first `inclined water maser disk'. We aim to investigate the nature of the maser by determining the location and the distribution of the maser emission at mas resolution and by associating it with the main nuclear components of IC485. In a broader context, this work might also provide further information for better understanding the physics and the disk/jet geometry in LINER or Seyfert galaxies. We observed in 2018 the nuclear region of IC485 in continuum and spectral-line mode with the VLBA and the EVN at L, C, and K bands (linear scales from ~3 to 0.2 pc). We detected 2 water maser components separated in velocity by 472 km/s, with one centred at the systemic velocity of the nuclear region and the other at a red-shifted velocity. We measured for the first time the absolute positions of these components with an accuracy of ~0.1 mas. Assuming a maser associated with an edge-on disk in Keplerian rotation, the estimated enclosed mass is M_BH = 1.2 x 10^7 M_sun, consistent with the expected mass for a SMBH in a LINER or Seyfert galaxy. The linear distribution of the maser components and a comparison with the high sensitivity GBT spectrum strongly suggest that the bulk of the maser emission is associated with an edge-on accretion disk. This makes IC485 a new candidate for a disk-maser galaxy at the distance of 122 Mpc. In particular, thanks to the upcoming radio facilities (e.g., the SKA and the ngVLA) IC485 will play an important role in our understanding of AGNs in an unexplored volume of Universe.
description: 13 pages, 10 figures, 6 tables, accepted by Astronomy & Astrophysics
A RISC-V MCU with adaptive reverse body bias and ultra-low-power retention mode in 22 nm FD-SOI
Creators: name: Bauer, Heiner
name: Stolba, Marco
name: Scholze, Stefan
name: Walter, Dennis
name: Mayr, Christian
name: Oefelein, Alexander
name: Höppner, Sebastian
name: Scharfe, André
name: Schraut, Flo
name: Eisenreich, Holger
Publisher: name: arXiv
Year: 2023
Subjects: subject: Hardware Architecture (cs.AR)
subject: FOS: Computer and information sciences

description: We present a low-power, energy efficient 32-bit RISC-V microprocessor unit (MCU) in 22 nm FD-SOI. It achieves ultra-low leakage,even at high temperatures, by using an adaptive reverse body biasing aware sign-off approach, a low-power optimized physical implementation, and custom SRAM macros with retention mode. We demonstrate the robustness of the chip with measurements over the full industrial temperature range, from -40 °C to 125 °C. Our results match the state of the art (SOTA) with 4.8 uW / MHz at 50 MHz in active mode and surpass the SOTA in ultra-low-power retention mode.
description: accepted at ISOCC 2023
Observational predictions for Thorne-Żytkow objects
Creators: name: Farmer, R.
name: Renzo, M.
name: Götberg, Y.
name: Bellinger, E.
name: Justham, S.
name: de Mink, S. E
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Thorne-$Ż$ytkow objects (T$Ż$O) are potential end products of the merger of a neutron star with a non-degenerate star. In this work, we have computed the first grid of evolutionary models of T$Ż$Os with the MESA stellar evolution code. With these models, we predict several observational properties of T$Ż$Os, including their surface temperatures and luminosities, pulsation periods, and nucleosynthetic products. We expand the range of possible T$Ż$O solutions to cover $3.45 \lesssim \log \left(T/K\right) \lesssim 3.65$ and $4.85 \lesssim \log \left(L/L_{\odot}\right) \lesssim 5.5$. Due to the much higher densities our T$Ż$Os reach compared to previous models, if T$Ż$Os form we expect them to be stable over a larger mass range than previously predicted, without exhibiting a gap in their mass distribution. Using the GYRE stellar pulsation code we show that T$Ż$Os should have fundamental pulsation periods of 1000--2000 days, and period ratios of $\approx$0.2--0.3. Models computed with a large 399 isotope fully-coupled nuclear network show a nucleosynthetic signal that is different to previously predicted. We propose a new nucleosynthetic signal to determine a star's status as a T$Ż$O: the isotopologues $^{44}\rm{Ti} \rm{O}_2$ and $^{44}\rm{Ti} \rm{O}$, which will have a shift in their spectral features as compared to stable titanium-containing molecules. We find that in the local Universe (~SMC metallicities and above) T$Ż$Os show little heavy metal enrichment, potentially explaining the difficulty in finding T$Ż$Os to-date.
description: 17 pages, 16 figures, 3 Tables, Accepted MNRAS, Zenodo data available https://doi.org/10.5281/zenodo.4534425
Three-Terminal Energy Harvester with Coupled Quantum Dots
Creators: name: Thierschmann, Holger
name: Sánchez, Rafael
name: Sothmann, Björn
name: Arnold, Fabian
name: Heyn, Christian
name: Hansen, Wolfgang
name: Buhmann, Hartmut
name: Molenkamp, Laurens W.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Rectification of thermal fluctuations in mesoscopic conductors is the key idea of today's attempts to build nanoscale thermoelectric energy harvesters in order to convert heat into a useful electric power. So far, most concepts make use of the Seebeck effect in a two-terminal geometry where heat and charge are both carried by the same particles. Here, we experimentally demonstrate the working principle of a new kind of energy harvester, proposed recently using two capacitively coupled quantum dots. We show that due to its novel three-terminal design which spatially separates the heat reservoir from the conductor circuit, the directions of charge and heat flow become decoupled in our device. This enables us to manipulate the direction of the generated charge current by means of external gate voltages while leaving the direction of heat flow unaffected. Our results pave the way for a new generation of multi-terminal, highly efficient nanoscale heat engines.