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Classifying Unidentified X-ray Sources in the Chandra Source Catalog Using a Multiwavelength Machine-learning Approach

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arXiv 2022年

作者： Yang, Hui Hare, Jeremy Kargaltsev, Oleg Volkov, Igor Chen, Steven Rangelov, Blagoy Department of Physics The George Washington University 725 21st St. NW WashingtonDC20052 United States NASA Goddard Space Flight Center GreenbeltMD20771 United States NASA Postdoctoral Program Fellow Department of Physics Texas State University 601 University Drive San MarcosTX78666 United States

The rapid increase in serendipitous X-ray source detections requires the development of novel approaches to efficiently explore the nature of X-ray sources. If even a fraction of these sources could be reliably classified, it would enable population studies for various astrophysical source types on a much larger scale than currently possible. Classification of large numbers of sources from multiple classes characterized by multiple properties (features) must be done automatically and supervised machine learning (ML) seems to provide the only feasible approach. We perform classification of Chandra Source Catalog version 2.0 (CSCv2) sources to explore the potential of the ML approach and identify various biases, limitations, and bottlenecks that present themselves in these kinds of studies. We establish the framework and present a flexible and expandable Python pipeline, which can be used and improved by others. We also release the training data set of 2941 X-ray sources with confidently established classes. In addition to providing probabilistic classifications of 66,369 CSCv2 sources (21% of the entire CSCv2 catalog), we perform several narrower-focused case studies (high-mass X-ray binary candidates and X-ray sources within the extent of the H.E.S.S. TeV sources) to demonstrate some possible applications of our ML approach. We also discuss future possible modifications of the presented pipeline, which are expected to lead to substantial improvements in classification confidences. Copyright © 2022, The Authors. All rights reserved.

关键词： Pipelines

Continuum reverberation mapping of MCG 08-11-011

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arXiv 2023年

作者： Fian, C. Chelouche, D. Kaspi, S. Figaredo, C. Sobrino Lewis, T. Catalan, S. Departamento de Astronomía y Astrofísica Universidad de Valencia Burjassot ValenciaE-46100 Spain School of Physics and Astronomy and Wise Observatory Raymond and Beverly Sackler Faculty of Exact Sciences Tel-Aviv University Tel-Aviv Israel Department of Physics Faculty of Natural Sciences University of Haifa Haifa3498838 Israel Haifa Research Center for Theoretical Physics and Astrophysics University of Haifa Haifa3498838 Israel NASA Postdoctoral Program Fellow NASA Goddard Space Flight Center Code 661 8800 Greenbelt Rd GreenbeltMD20771 United States

Aims. We report the results from a photometric reverberation mapping campaign carried out with the C18 telescope at the Wise Observatory from 2019 to 2020, targeting the active galactic nucleus (AGN) MCG 08-11-011. The monitoring was conducted on a daily basis with specially designed narrow-band filters, spanning from optical to near-infrared wavelengths (∼ 4000 to 8000Å) and avoiding prominent broad emission lines. We aim to measure inter-band continuum time lags, determine the size-wavelength relation, and estimate the host-subtracted AGN luminosity for this system. Methods. We used the point-spread function photometry to extract the continuum light curves and measure the inter-band time lags using several methods, including the interpolated cross-correlation function, the z-transformed discrete correlation function, a von Neumann estimator, JAVELIN (in spectroscopic and photometric mode), MICA, and a multivariate correlation function. Results. We find wavelength-dependent lags, τ(λ), up to ∼7 days between the multiband light curves of MCG 08-11-011. The observed lags are larger than predictions based on standard thin-disk theory by a factor of ∼ 3 − 7. We discern a significantly steeper (τ ∝ λ4.74) size-wavelength relation than the τ ∝ λ4/3 expected for a geometrically thin and optically thick accretion disk, which may result from the contribution of diffuse continuum emission to the flux. These results are similar to those found by previous continuum reverberation mapping campaigns. © 2023, CC BY.

关键词： Optical transfer function

Single-Shot Readout of a Solid-State Spin in a Decoherence-Free Subspace

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Physical Review Applied 2021年第3期15卷 L031002-L031002页

作者： D. Farfurnik R. M. Pettit Z. Luo E. Waks Department of Electrical and Computer Engineering Institute for Research in Electronics and Applied Physics and Joint Quantum Institute University of Maryland College Park Maryland 20742 USA Intelligence Community Postdoctoral Research Fellowship Program University of Maryland College Park Maryland 20742 USA

The efficient single-photon-emission capabilities of quantum dot molecules position them as promising platforms for quantum information processing. Furthermore, quantum dot molecules feature a “decoherence-free” subspace that enables spin qubits with long coherence times. To efficiently read out the spin state within this subspace requires the optical cycling of isolated transitions that originate from a triplet manifold within the quantum dot molecule. We propose and theoretically study a two-stage spin-readout protocol within this decoherence-free subspace that allows single-shot readout performance. The process incorporates a microwave π pulse and optical cycling of the isolated transitions, which induces fluorescence that allows us to identify the initial spin state. This protocol offers enhanced readout fidelity compared to previous schemes that rely on the excitation of transitions that strongly decay to multiple ground states or require long initialization via slow optically forbidden transitions. By simulating the performance of the protocol, we show that an optimal spin-readout fidelity of over 97% and single-shot readout performance are achievable for a photon-collection efficiency of just 0.12%. This high readout performance for such realistic photon-collection conditions within the decoherence-free subspace expands the potential of quantum dot molecules as building blocks for quantum networks.

关键词： Optoelectronics Quantum information with solid state qubits Quantum networks Single photon sources Double quantum dots Coherent control Microwave techniques Quantum master equation

Modeling phonon-mediated quasiparticle poisoning in superconducting qubit arrays

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arXiv 2024年

作者： Yelton, Eric Larson, Clayton P. Iaia, Vito Dodge, Kenneth La Magna, Guglielmo Baity, Paul G. Pechenezhskiy, Ivan V. McDermott, Robert Kurinsky, Noah A. Catelani, Gianluigi Plourde, Britton L.T. Department of Physics Syracuse University SyracuseNY13244-1130 United States Intelligence Community Postdoctoral Research Fellowship Program Department of Physics Syracuse University SyracuseNY13244-1130 United States Forschungszentrum Jülich Jülich52425 Germany Quantum Research Center Technology Innovation Institute Abu Dhabi9639 United Arab Emirates Computational Science Initiative Brookhaven National Laboratory UptonNY11973 United States Department of Physics University of Wisconsin-Madison MadisonWI53706 United States Kavli Institute for Particle Astrophysics and Cosmology SLAC National Accelerator Laboratory Menlo ParkCA94025 United States

Correlated errors caused by ionizing radiation impacting superconducting qubit chips are problematic for quantum error correction. Such impacts generate quasiparticle (QP) excitations in the qubit electrodes, which temporarily reduce qubit coherence significantly. The many energetic phonons produced by a particle impact travel efficiently throughout the device substrate and generate quasiparticles with high probability, thus causing errors on a large fraction of the qubits in an array simultaneously. We describe a comprehensive strategy for the numerical simulation of the phonon and quasiparticle dynamics in the aftermath of an impact. We compare the simulations with experimental measurements of phonon-mediated QP poisoning and demonstrate that our modeling captures the spatial and temporal footprint of the QP poisoning for various configurations of phonon downconversion structures. We thus present a path forward for the operation of superconducting quantum processors in the presence of ionizing radiation. Copyright © 2024, The Authors. All rights reserved.

关键词： Qubits

Characterizing the γ-ray Emission from FR0 Radio Galaxies

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arXiv 2023年

作者： Khatiya, Nikita S. Boughelilba, Margot Karwin, Christopher M. McDaniel, Alex Zhao, Xiurui Ajello, Marco Reimer, Anita Hartmann, Dieter H. Department of Physics and Astronomy Clemson University ClemsonSC29634 United States Universität Innsbruck Institut für Astro- und Teilchenphysik Innsbruck6020 Austria NASA Postdoctoral Program Fellow NASA Goddard Space Flight Center GreenbeltMD20771 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States

FR0 galaxies constitute the most abundant jet population in the local Universe. With their compact jet structure, they are broadband photon emitters and have been proposed as multi-messenger sources. Recently, these sources have been detected for the first time in γ rays. Using a revised FR0 catalog, we confirm that the FR0 population as a whole are γ-ray emitters, and we also identify two significant sources. For the first time, we find a correlation between the 5 GHz core radio luminosity and γray luminosity in the 1 - 800 GeV band, having a 4.5σ statistical significance. This is clear evidence that the jet emission mechanism is similar in nature for FR0s and the well-studied canonical FR (FRI and FRII) radio galaxies. Furthermore, we perform broadband SED modeling for the significantly detected sources as well as the subthreshold source population using a one-zone SSC model. Within the maximum jet power budget, our modeling shows that the detected gamma rays from the jet can be explained as inverse Compton photons. To explain the multi-wavelength observations for these galaxies, the modeling results stipulate a low bulk Lorentz factor and a jet composition far from equipartition, with the particle energy density dominating over the magnetic field energy density. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

Mid-circuit correction of correlated phase errors using an array of spectator qubits

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arXiv 2022年

作者： Singh, Kevin Bradley, Conor E. Anand, Shraddha Ramesh, Vikram White, Ryan Bernien, Hannes Intelligence Community Postdoctoral Research Fellowship Program Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States Department of Physics University of Chicago ChicagoIL60637 United States

Scaling up invariably error-prone quantum processors is a formidable challenge. While quantum error correction ultimately promises fault-tolerant operation, the required qubit overhead and error thresholds are daunting, and many codes break down under correlated noise. Recent proposals have suggested a complementary approach based on co-located, auxiliary ‘spectator’ qubits. These act as in-situ probes of noise, and enable real-time, coherent corrections of the resulting errors on the data qubits. Here, we use an array of cesium spectator qubits to correct correlated phase errors on an array of rubidium data qubits. Crucially, by combining in-sequence readouts, data processing, and feed-forward operations, these correlated errors are suppressed within the execution of the quantum circuit. The protocol is broadly applicable to quantum information platforms, and our approach establishes key tools for scaling neutral-atom quantum processors: mid-circuit readout of atom arrays, real-time processing and feed-forward, and coherent mid-circuit reloading of atomic qubits. Copyright © 2022, The Authors. All rights reserved.

关键词： Timing circuits

Compressed Parametric and Non-Parametric Approximations to the Gravitational Wave Likelihood

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arXiv 2022年

作者： Delfavero, Vera O’Shaughnessy, Richard Wysocki, Daniel Yelikar, Anjali NASA Postdoctoral Program Astrophysics Science Division NASA Goddard Space Flight Center GreenbeltMD20771 United States Center for Computational Relativity and Gravitation Rochester Institute of Technology RochesterNY14623 United States Department of Physics University of Wisconsin–Milwaukee MilwaukeeWI53201 United States

Gravitational-wave observations of quasicircular compact binary mergers imply complicated posterior measurements of their parameters. Though Gaussian approximations to the pertinent likelihoods have decades of history in the field, the relative generality and practical utility of these approximations hasn’t been appreciated, given focus on careful, comprehensive generic Bayesian parameter inference. Building on our previous work in three dimensions, we demonstrate by example that bounded multivariate normal likelihood approximations are a sufficiently accurate representation of the full likelihood of observed gravitational-wave sources. Fits for each event are published in the Gravitational-Wave Transient Catalogs at https://***/xevra/nal-data, along with a code release at https://***/xevra/gwalk. We argue our approximations are more than accurate enough for population inference and introduce much smaller errors than waveform model systematics. To demonstrate the utility of these approximations as parametric models for the likelihood of individual gravitational-wave sources, we show examples of their application to modeling the population of observed gravitational-wave sources as well as low-latency parameter inference. Copyright © 2022, The Authors. All rights reserved.

关键词： Gravity waves

Tunable Exciton-Hybridized Magnon Interactions in a Layered Semiconductor

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arXiv 2022年

作者： Diederich, Geoffrey M. Cenker, John Ren, Yafei Fonseca, Jordan Chica, Daniel G. Bae, Youn Jue Zhu, Xiaoyang Roy, Xavier Cao, Ting Xiao, Di Xu, Xiaodong Intelligence Community Postdoctoral Research Fellowship Program University of Washington SeattleWA United States Department of Physics University of Washington SeattleWA United States Department of Materials Science and Engineering University of Washington SeattleWA United States Department of Chemistry Columbia University New YorkNY10027 United States

The interaction between distinct excitations in solids is of both fundamental interest and technological importance. One example of such interactions is coupling between an exciton, a Coulomb bound electron-hole pair, and a magnon, a collective spin excitation. The recent emergence of van der Waals magnetic semiconductors1 provides a powerful platform for exploring these exciton-magnon interactions and their fundamental properties, such as strong correlation2, as well as their photo-spintronic and quantum transduction3 applications. Here we demonstrate precise control of coherent exciton-magnon interactions in the layered magnetic semiconductor CrSBr. We show that by controlling the direction of applied magnetic fields relative to the crystal axes, and thus the rotational symmetry of the magnetic system4, we can tune not only the exciton coupling to the bright magnon, but also to an optically dark mode via magnon hybridization. The exciton-magnon coupling and associated magnon dispersion curves can be further modulated by applying a uniaxial strain. At the critical strain, a dispersionless dark magnon band emerges. Our results demonstrate unprecedented control of the opto-mechanical-magnonic coupling, and a step towards the predictable and controllable implementation of hybrid quantum magnonics5–11 Copyright © 2022, The Authors. All rights reserved.

关键词： Excitons

Unveiling the Journey of a Highly Inclined CME Insights from the March 13, 2012 Event with 110° Longitudinal Separation

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arXiv 2024年

作者： Carcaboso, F. Dumbović, M. Kay, C. Lario, D. Jian, L.K. Wilson, L.B. Gómez-Herrero, R. Temmer, M. Heinemann, S.G. Nieves-Chinchilla, T. Veronig, A.M. NASA Postdoctoral Program Fellow NASA Goddard Space Flight Center GreenbeltMD United States Heliophysics Science Division NASA Goddard Space Flight Center GreenbeltMD United States Physics Department The Catholic University of America WashingtonDC United States Hvar Observatory Faculty of Geodesy University of Zagreb Kaciceva 26 ZagrebHR-10000 Croatia Plaza de San Diego s/n Alcalá de Henares Madrid28801 Spain Institute of Physics University of Graz Universitätsplatz 5 Graz8010 Austria Department of Physics University of Helsinki P.O. Box 64 Helsinki00014 Finland Kanzelhöhe Observatory for Solar and Environmental Research University of Graz Austria

Context. A fast (∼2000 km/s) and wide (>110°) Coronal Mass Ejection (CME) erupted from the Sun on March 13, 2012. Its interplanetary counterpart was detected in situ two days later by STEREO-A and near-Earth spacecraft, such as ACE, Wind and Cluster. We suggest that at 1 au the CME extended at least 110° in longitude, with Earth crossing its east flank and STEREO-A crossing its west flank. Despite their separation, measurements from both positions showed very similar in situ CME signatures. The solar source region where the CME erupted was surrounded by three coronal holes (CHs). Their locations with respect to the CME launch site were east (negative polarity), southwest (positive polarity) and west (positive polarity). The solar magnetic field polarity of the area covered by each CH matches that observed at 1 au in situ. Suprathermal electrons at each location showed mixed signatures with only some intervals presenting clear counterstreaming flows as the CME transits both locations. The strahl population coming from the shortest magnetic connection of the structure to the Sun showed more intensity. Aims. The aim of this work is to understand the propagation and evolution of the CME and its interaction with the surrounding CHs, to explain the similarities and differences between the observations at each spacecraft, and report what it would be one of the most longitudinal expanded CME structures measured in situ. Methods. Known properties of the large-scale structures from a variety of catalogues and previous studies are used to have a better overview of this particular event. In addition, multipoint observations are used to reconstruct the 3D geometry of the CME and determine the context of the solar and heliospheric conditions before the CME eruption and during its propagation. The graduated cylindrical shell model (GCS) is used to reproduce the orientation, size and speed of the structure with a simple geometry. Also, the Drag-Based Model (DBM) is utilised to unde

关键词： Drag