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The EB-correlation in Resolved Polarized Images: Connections to Astrophysics of Black Holes

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arXiv 2023年

作者： Emami, Razieh Doeleman, Sheperd S. Wielgus, MacIek Chang, Dominic Chatterjee, Koushik Smith, Randall Liska, Matthew Steiner, James F. Ricarte, Angelo Narayan, Ramesh Tremblay, Grant Finkbeiner, Douglas Hernquist, Lars Chan, Chi-Kwan Blackburn, Lindy Prather, Ben S. Tiede, Paul Broderick, Avery E. Vogelsberger, Mark Alcock, Charles Roelofs, Freek Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States CCS-2 Los Alamos National Laboratory P.O. Box 1663 Los AlamosNM87545 United States Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Department of Physics Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States

We present an in-depth analysis of a newly proposed correlation function in visibility space, between the E and B modes of the linear polarization, hereafter the EB-correlation, for a set of time-averaged GRMHD simulations compared with the phase map from different semi-analytic models as well as the Event Horizon Telescope (EHT) 2017 data for M87∗source. We demonstrate that the phase map of the time-averaged EB-correlation contains novel information that might be linked to the BH spin, accretion state and the electron temperature. A detailed comparison with a semi-analytic approach with different azimuthal expansion modes shows that to recover the morphology of the real/imaginary part of the correlation function and its phase, we require higher orders of these azimuthal modes. To extract the phase features, we propose to use the Zernike polynomial reconstruction developing an empirical metric to break degeneracies between models with different BH spins that are qualitatively similar. We use a set of different geometrical ring models with various magnetic and velocity field morphologies and show that both the image space and visibility based EB-correlation morphologies in MAD simulations can be explained with simple fluid and magnetic field geometries as used in ring models. SANEs by contrast are harder to model, demonstrating that the simple fluid and magnetic field geometries of ring models are not sufficient to describe them owing to higher Faraday Rotation depths. A qualitative comparison with the EHT data demonstrates that some of the features in the phase of EB-correlation might be well explained by the current models for BH spins as well as electron temperatures, while others may require a larger theoretical surveys. © 2023, CC BY.

关键词： Polarization

The Black Hole Explorer: Motivation and Vision

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arXiv 2024年

作者： Johnson, Michael D. Akiyama, Kazunori Baturin, Rebecca Bilyeu, Bryan Blackburn, Lindy Boroson, Don Cárdenas-Avendaño, Alejandro Chael, Andrew Chan, Chi-Kwan Chang, Dominic Cheimets, Peter Chou, Cathy Doeleman, Sheperd S. Farah, Joseph Galison, Peter Gamble, Ronald Gammie, Charles F. Gelles, Zachary Gómez, José L. Gralla, Samuel E. Grimes, Paul Gurvits, Leonid I. Hadar, Shahar Haworth, Kari Hada, Kazuhiro Hecht, Michael H. Honma, Mareki Houston, Janice Hudson, Ben Issaoun, Sara Jia, He Jorstad, Svetlana Kauffmann, Jens Kovalev, Yuri Y. Kurczynski, Peter Lafon, Robert Lupsasca, Alexandru Lehmensiek, Robert Ma, Chung-Pei Marrone, Daniel P. Marscher, Alan P. Melnick, Gary J. Narayan, Ramesh Niinuma, Kotaro Noble, Scott C. Palmer, Eric J. Palumbo, Daniel C.M. Paritsky, Lenny Peretz, Eliad Pesce, Dominic Plavin, Alexander Quataert, Eliot Rana, Hannah Ricarte, Angelo Roelofs, Freek Shtyrkova, Katia Sinclair, Laura C. Small, Jeffrey Kumara, Sridharan Tirupati Srinivasan, Ranjani Strominger, Andrew Tiede, Paul Tong, Edward Wang, Jade Weintroub, Jonathan Wielgus, Maciek Wong, George Zhang, Xinyue Alice Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States Black Hole Initiative Harvard University 20 Garden Street CambridgeMA02138 United States Haystack Observatory Massachusetts Institute of Technology WestfordMA01886 United States Mizusawa VLBI Observatory National Astronomical Observatory of Japan Iwate023-0861 Japan MIT Lincoln Laboratory LexingtonMA02421 United States Princeton Gravity Initiative Princeton University PrincetonNJ08544 United States Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Data Science Institute University of Arizona 1230 N. Cherry Ave. TucsonAZ85721 United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita TucsonAZ85721 United States Las Cumbres Observatory 6740 Cortona Drive GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Department of History of Science Harvard University CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States NASA Goddard Space Flight Center GreenbeltMD20771 United States Departments of Astronomy and of Physics University of Illinois UrbanaIL61801 United States Instituto de Astrofísica de Andalucía CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Department of Physics University of Arizona TucsonAZ85719 United States Joint Institute for VLBI ERIC Dwingeloo7991PD Netherlands Faculty of Aerospace Engineering Delft University of Technology Delft2629 HS Netherlands Department of Mathematics and Physics University of Haifa at Oranim Kiryat Tivon3600600 Israel Haifa Research Center for Theoretical Physics and Astrophysics University of Haifa Haifa3498838 Israel 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-

We present the Black Hole Explorer (BHEX), a mission that will produce the sharpest images in the history of astronomy by extending submillimeter Very-Long-Baseline Interferometry (VLBI) to space. BHEX will discover and measure the bright and narrow "photon ring" that is predicted to exist in images of black holes, produced from light that has orbited the black hole before escaping. This discovery will expose universal features of a black hole's spacetime that are distinct from the complex astrophysics of the emitting plasma, allowing the first direct measurements of a supermassive black hole's spin. In addition to studying the properties of the nearby supermassive black holes M87*and Sgr A*, BHEX will measure the properties of dozens of additional supermassive black holes, providing crucial insights into the processes that drive their creation and growth. BHEX will also connect these supermassive black holes to their relativistic jets, elucidating the power source for the brightest and most efficient engines in the universe. BHEX will address fundamental open questions in the physics and astrophysics of black holes that cannot be answered without submillimeter space VLBI. The mission is enabled by recent technological breakthroughs, including the development of ultra-high-speed downlink using laser communications, and it leverages billions of dollars of existing ground infrastructure. We present the motivation for BHEX, its science goals and associated requirements, and the pathway to launch within the next decade. © 2024, CC BY.

关键词： Photons

On the cross-validation bias due to unsupervised preprocessing

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arXiv 2019年

作者： Moscovich, Amit Rosset, Saharon Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Department of Statistics and Operations Research Tel-Aviv University Tel-Aviv Israel

Cross-validation is the de facto standard for predictive model evaluation and selection. In proper use, it provides an unbiased estimate of a model's predictive performance. However, data sets often undergo various forms of data-dependent preprocessing, such as mean-centering, rescaling, dimensionality reduction, and outlier removal. It is often believed that such preprocessing stages, if done in an unsupervised manner (that does not incorporate the class labels or response values) are generally safe to do prior to cross-validation. In this paper, we study three commonly-practiced preprocessing procedures prior to a regression analysis: (i) variance-based feature selection;(ii) grouping of rare categorical features;and (iii) feature rescaling. We demonstrate that unsupervised preprocessing can, in fact, introduce a substantial bias into cross-validation estimates and potentially hurt model selection. This bias may be either positive or negative and its exact magnitude depends on all the parameters of the problem in an intricate manner. Further research is needed to understand the real-world impact of this bias across different application domains, particularly when dealing with small sample sizes and high-dimensional *** Codes 62-07 Copyright © 2019, The Authors. All rights reserved.

关键词： Regression analysis

Measures of Efficiency of Convection

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Research Notes of the AAS 2022年第2期6卷

作者： Adam S. Jermyn Evan H. Anders Daniel Lecoanet Matteo Cantiello Jared A. Goldberg Center for Computational Astrophysics Flatiron Institute New York NY 10010 USA adamjermyn@*** CIERA Northwestern University Evanston IL 60201 USA Department of Engineering Sciences and Applied Mathematics Northwestern University Evanston IL 60208 USA Department of Astrophysical Sciences Princeton University Princeton NJ 08544 USA Department of Physics University of California Santa Barbara CA 93106 USA

Convection is efficient when advection matters much more than thermal diffusion. Despite this conceptually simple definition, there are several different measures of convective efficiency which are not quite equivalen... 详细信息

关键词： Stellar physics Stellar evolutionary models Stellar convective zones

Intramolecular Structural Heterogeneity altered by Long-range Contacts in an Intrinsically Disordered Protein

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arXiv 2022年

作者： Koren, Gil Meir, Sagi Holschuh, Lennard Mertens, Haydyn D.T. Ehm, Tamara Yahalom, Nadav Golombek, Adina Schwartz, Tal Svergun, Dmitri I. Saleh, Omar A. Dzubiella, Joachim Beck, Roy Raymond & Beverly Sackler School of Physics & Astronomy Tel Aviv University Tel Aviv6997801 Israel The Center for Physics & Chemistry of Living Systems Tel Aviv University Tel Aviv6997801 Israel The Center for NanoTechnology & NanoScience Tel Aviv University Tel Aviv6997801 Israel Applied Theoretical Physics-Computational Physics Physikalisches Institut Albert-Ludwigs-Universit Freiburg FreiburgD-79104 Germany European Molecular Biology Laboratory Hamburg Unit Hamburg22607 Germany Faculty of Physics Center for NanoScience Ludwig-Maximilians-Universität MünchenD-80539 Germany School of Chemistry Raymond and Beverly Sackler Faculty of Exact Sciences Tel Aviv University Center for Light-Matter Interaction Tel Aviv University Tel Aviv6997801 Israel The Center for Nanoscience and Nanotechnology Tel Aviv University Tel Aviv69978 Israel BMSE Program University of California Santa BarbaraCA93110 United States Materials Department University of California Santa BarbaraCA93110 United States Cluster of Excellence livMatS @ FIT Freiburg Center for Interactive Materials and Bioinspired Technologies Albert-Ludwigs-Universit Freiburg FreiburgD-79104 Germany

Short-range interactions and long-range contacts drive the 3D folding of structured proteins. The proteins’ structure has a direct impact on their biological function. However, nearly 40% of the eukaryotes proteome is composed of intrinsically disordered proteins (IDPs) and protein regions that fluctuate between ensembles of numerous conformations. Therefore, to understand their biological function, it is critical to depict how the structural ensemble statistics correlate to the IDPs’ amino acid sequence. Here, using small-angle x-ray scattering (SAXS) and time-resolved Förster resonance energy transfer (trFRET), we study the intra-molecular structural heterogeneity of the neurofilament low intrinsically disordered tail domain (NFLt). Using theoretical results of polymer physics, we find that the Flory scaling exponent of NFLt sub-segments correlates linearly with their net charge, ranging from statistics of ideal to self-avoiding chains. Surprisingly, measuring the same segments in the context of the whole NFLt protein, we find that regardless of the peptide sequence, the segments’ structural statistics are more expanded than when measured independently. Our findings show that while polymer physics can, to some level, relate the IDP’s sequence to its ensemble conformations, long-range contacts between distant amino acids play a crucial role in determining intra-molecular structures. This emphasizes the necessity of advanced polymer theories to fully describe IDPs ensembles with the hope it will allow us to model their biological function. © 2022, CC BY.

关键词： Proteins

Exponential convergence of the deep neural network approximation for analytic functions Dedicated to Professor Ta Tsien Li on the Occasion of His 80th Birthday

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Science China mathematics 2018年第10期61卷 1733-1740页

作者： Weinan E Qingcan Wang Department of Mathematics and PACM Princeton University Princeton NJ 08544 USA Center for Big Data Research Peking University Beijing 100871 China Beijing Institute of Big Data Research Beijing 100871 China Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 USA

We prove that for analytic functions in low dimension, the convergence rate of the deep neural network approximation is exponential.

关键词： neural networks approximation theory analytic functions

Deep learning inter-atomic potential model for accurate irradiation damage simulationsa)

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arXiv 2019年

作者： Wang, Hao Guo, Xun Zhang, Linfeng Wang, Han Xue, Jianming State Key Laboratory of Nuclear Physics and Technology School of Physics CAPT HEDPS IFSA Collaborative Innovation Center of MoE College of Engineering Peking University Beijing100871 China Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100871 China State Key Laboratory of Nuclear Physics and Technology School of Physics CAPT HEDPS IFSA Collaborative Innovation Center of MoE College of Engineering Peking University Beijing100871 China

We propose a hybrid scheme that interpolates smoothly the Ziegler-Biersack-Littmark (ZBL) screened nuclear repulsion potential with a newly developed deep learning potential energy model. The resulting DP-ZBL model can not only provide overall good performance on the predictions of near-equilibrium material properties but also capture the right physics when atoms are extremely close to each other, an event that frequently happens in computational simulations of irradiation damage events. We applied this scheme to the simulation of the irradiation damage processes in the face-centered-cubic aluminium system, and found better descriptions in terms of the defect formation energy, evolution of collision cascades, displacement threshold energy, and residual point defects, than the widely-adopted ZBL modified embedded atom method potentials and its variants. Our work provides a reliable and feasible scheme to accurately simulate the irradiation damage processes and opens up new opportunities to solve the predicament of lacking accurate potentials for enormous newly-discovered materials in the irradiation effect field. Copyright © 2019, The Authors. All rights reserved.

关键词： Potential energy

Interpretation of gravity satellite data to delineate structural features connected to geothermal resources at Bur Ni Geureudong geothermal field 3

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Interpretation of gravity satellite data to delineate struct...

3rd International Conference on Natural and Environmental Sciences 2019, ICONES 2019

作者： Putri, D.R. Nanda, M. Rizal, S. Idroes, R. Ismail, N. Doctoral Program of Mathematics and Applied Science Universitas Syiah Kuala Banda Aceh23111 Indonesia Marine Sciences Department Universitas Syiah Kuala Banda Aceh23111 Indonesia Department of Chemistry Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Kopelma Darussalam Banda Aceh23111 Indonesia Department of Pharmacy Faculty of Mathematics and Natural Sciences Universitas Syiah Kuala Kopelma Darussalam Banda Aceh23111 Indonesia Department of Physics Faculty of Mathematics and Natural Science Universitas Syiah Kuala Banda Aceh23111 Indonesia

The gravity method is broadly used in analyzing potential geothermal studies. The method can be used for determining potential areas, reservoir locations, and geological structure investigation. In this paper, satellite gravity data was applied for better understand the geological conditions connected with the geothermal system of Bur Ni Geureudong geothermal field, Bener Meriah District, Aceh, Indonesia. Open access Free Air anomaly data were provided by satellite geodesy information with 1 minute-grid. The data were reduced to obtain Bouguer anomaly distribution in the study area. Tilt derivative (TDR) technique was applied to Bouguer anomaly to enhance linear trends of geological structures. The aim of this analytical technique is able to clearly display faults correlated with geothermal manifestations around the Bur Ni Geureudong geothermal field. The complete Bouguer anomaly range of 20 mGal up to 170 mGal covers Bur Ni Geureudong volcano complex. A low Bouguer anomaly is located in all summits of volcanoes that are included in Bur Ni Geureudong Volcano Complex;those are summits of Bur Geureudong volcano, Bur Ni Telong Volcano, Pepanji Mountain, and Salah Nama Mountain. The low Bouguer anomaly is associated with the andesitic flow and volcanic ashes. The higher Bouguer Anomaly is reflected in high-density basement rock in the west of Geureudong Volcano. Tilt derivative (TDR) shows geological structures more detail, particularly, the tilt derivative (TDR) clearly detects two fault structures over the study area presented by a tilt value of zero. The results will be useful as basic information in exploration study of Bur Ni Geureudong geothermal field. © 2019 Published under licence by IOP Publishing Ltd.

关键词： Volcanoes

Convective Boundary Mixing Processes

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Research Notes of the AAS 2022年第2期6卷

作者： Evan H. Anders Adam S. Jermyn Daniel Lecoanet J. R. Fuentes Lydia Korre Benjamin P. Brown Jeffrey S. Oishi CIERA Northwestern University Evanston IL 60201 USA evan.anders@northwestern.edu Center for Computational Astrophysics Flatiron Institute New York NY 10010 USA Department of Engineering Sciences and Applied Mathematics Northwestern University Evanston IL 60208 USA Department of Physics and McGill Space Institute McGill University 3600 rue University Montreal QC H3A 2T8 Canada Department of Applied Mathematics University of Colorado Boulder CO 80309-0526 USA Laboratory for Atmospheric and Space Physics Boulder CO 80303 USA University of Colorado Department of Astrophysical and Planetary Sciences Boulder CO 80309 USA Bates College Department of Physics and Astronomy Lewiston Maine 04240 USA

Convective motions extend beyond the nominal boundaries of a convection zone. These motions mix fluid through multiple mechanisms collectively called 'convective boundary mixing.' In this note, we discuss three distinct fluid dynamical processes: convective overshoot, entrainment, and penetrative convection. We describe the structure of a convective boundary that these processes create. To resolve discrepancies between models and observations, the stellar astrophysics community should distinguish between these processes and parameterize each of them separately in 1D evolutionary models.

关键词： Stellar convective zones Stellar physics Stellar evolutionary models