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Effects of galaxy environment on merger fraction?

Astronomy and Astrophysics 2024年 686卷

作者： Pearson, W.J. Santos, D.J.D. Goto, T. Huang, T.-C. Kim, S.J. Matsuhara, H. Pollo, A. Ho, S.C.-C. Hwang, H.S. Malek, K. Nakagawa, T. Romano, M. Serjeant, S. Suelves, L.E. Shim, H. White, G.J. National Centre for Nuclear Research Pasteura 7 Warszawa02-093 Poland Max Planck Institute for Extraterrestrial Physics Gießenbachstraße 1 Garching85748 Germany Institute of Astronomy National Tsing Hua University 101 Section 2. Kuang-Fu Road Hsinchu30013 Taiwan Department of Space and Astronautical Science Graduate University for Advanced Studies SOKENDAI Shonankokusaimura Hayama Miura District Kanagawa240-0193 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3-1-1 Yoshinodai Chuo-ku Kanagawa Sagamihara252-5210 Japan Research School of Astronomy and Astrophysics The Australian National University CanberraACT2611 Australia Centre for Astrophysics and Supercomputing Swinburne University of Technology PO Box 218 HawthornVIC3122 Australia OzGrav The Australian Research Council Centre of Excellence for Gravitational Wave Discovery HawthornVIC3122 Australia ASTRO3D The Australian Research Council Centre of Excellence for All-sky Astrophysics in 3D CanberraACT2611 Australia Astronomy Program Department of Physics and Astronomy Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of SNU Astronomy Research Center Seoul National University 1 Gwanak-ro Gwanak-gu Seoul08826 Korea Republic of INAF – Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 Padova35122 Italy School of Physical Sciences The Open University Walton Hall Milton KeynesMK7 6AA United Kingdom Department of Earth Science Education Kyungpook National University 80 Daehak-ro Buk-gu Daegu41566 Korea Republic of Space Science and Technology Division RALSpace STFC Rutherford Appleton Laboratory Chilton DidcotOX11 0QX United Kingdom

Aims. In this work we examine how environment influences the merger fraction, from the low density field environment to higher density groups and clusters. We also study how the properties of a group or cluster, as well as the position of a galaxy in the group or cluster, influences the merger fraction. Methods. We identified galaxy groups and clusters in the North Ecliptic Pole using a friends-of-friends algorithm and the local density. Once identified, we determined the central galaxies, group radii, velocity dispersions, and group masses of these groups and clusters. Merging systems were identified with a neural network as well as visually. With these identifications and properties of groups and clusters and merging galaxy identifications, we examined how the merger fraction changes as the local density changes for all galaxies as well as how the merger fraction changes as the properties of the groups or clusters change. Results. We find that the merger fraction increases as local density increases and decreases as the velocity dispersion increases, as is often found in the literature. A decrease in merger fraction as the group mass increases is also found. We also find that groups with larger radii have higher merger fractions. The number of galaxies in a group does not influence the merger fraction. Conclusions. The decrease in merger fraction as group mass increases is a result of the link between group mass and velocity dispersion. Hence, this decrease in merger fraction with increasing mass is a result of the decrease of merger fraction with velocity dispersion. The increasing relation between group radii and merger fraction may be a result of larger groups having smaller velocity dispersion at a larger distance from the centre or larger groups hosting smaller, infalling groups with more mergers. However, we do not find evidence of smaller groups having higher merger fractions. c The Authors 2024.

关键词： Galaxies

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Virtual Parity-Time Symmetry

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Physical Review Letters 2020年第19期124卷 193901-193901页

作者： Huanan Li Ahmed Mekawy Alex Krasnok Andrea Alù Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Department of Electrical Engineering City College of The City University of New York New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10016 USA

Parity-time (PT) symmetry has recently been opening exciting directions in photonics, yet the required careful balance of loss and gain has been hindering its widespread applicability. Here, we propose a gain-free route to PT symmetry by extending it to complex-frequency excitations that can mimic gain in passive systems. Based on the concept of virtual absorption, extended here to implement also virtual gain, we implement PT symmetry in the complex-frequency plane and realize its landmark effects, such as broken phase transitions, anisotropic transmission resonances, and laser-absorber pairs, in a fully passive, hence inherently stable, system. These results open a path to establish PT symmetry and non-Hermitian physics in passive platforms.

关键词： Metamaterials PT-symmetry Electromagnetic wave theory

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Extraction of isotropic electron-nuclear gyperfine coupling constants of paramagnetic point defects from near-zero field magnetoresistance spectra via least squares fitting to models developed from the stochastic quantum liouville equation

arXiv

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arXiv 2020年

作者： Frantz, Elias B. Harmon, Nicholas J. McMillan, Stephen R. Moxim, Stephen J. Flatté, Michael E. Lenahan, Patrick M. Intercollege Graduate Degree Program in Materials Science and Engineering Pennsylvania State University University ParkPA16802 United States Department of Physics University of Evansville EvansvilleIN47722 United States Department of Physics and Astronomy University of Iowa Iowa CityIA52242 United States Department of Engineering Science and Mechanics Pennsylvania State University University ParkPA16802 United States

We report on a method by which we can systematically extract spectroscopic information such as isotropic electron-nuclear hyperfine coupling constants from near-zero field magnetoresistance (NZFMR) spectra. The method utilizes a least squares fitting of models developed from the stochastic quantum Liouville equation. We applied our fitting algorithm to two distinct material systems: Si/SiO2 metal oxide field effect transistors (MOSFETs), and a-Si:H metal insulator semiconductor (MIS) capacitors. Our fitted results and hyperfine parameters are in reasonable agreement with existing knowledge of the defects present in the systems. Our work indicates that the NZFMR response and fitting of the NZFMR spectrum via models developed from the stochastic quantum Liouville equation could be a relatively simple yet powerful addition to the family of spin-based techniques used to explore the chemical and structural nature of point defects in semiconductor devices and insulators. Copyright © 2020, The Authors. All rights reserved.

关键词： Point defects

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Advanced phase-change materials for enhanced meta-displays

arXiv

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arXiv 2021年

作者： Hemmatyar, Omid Abdollahramezani, Sajjad Lepeshov, Sergey Krasnok, Alex Brown, Tyler Alù, Andrea Adibi, Ali School of Electrical and Computer Engineering Georgia Institute of Technology 778 Atlantic Drive NW AtlantaGA30332-0250 United States ITMO University St. Petersburg197101 Russia Photonics Initiative Advanced Science Research Center City University of New York New YorkNY10031 United States Physics Program Graduate Center City University of New York New YorkNY10016 United States

Structural colors generated due to light scattering from static all-dielectric metasurfaces have successfully enabled high-resolution, high-saturation and wide-gamut color printing applications. Despite recent advances, most demonstrations of these structure-dependent colors lack post-fabrication tunability that hinders their applicability for front-end dynamic display technologies. Phase-change materials (PCMs), with significant contrast of their optical properties between their amorphous and crystalline states, have demonstrated promising potentials in reconfigurable nanophotonics. Herein, we leverage a tunable all-dielectric reflective metasurface made of a newly emerged class of low-loss optical PCMs with superb characteristics, i.e., antimony trisulphide (Sb2S3), antimony triselenide (Sb2Se3), and binary germanium-doped selenide (GeSe3), to realize switchable, high-saturation, high-efficiency and high-resolution structural colors. Having polarization sensitive building blocks, the presented metasurface can generate two different colors when illuminated by two orthogonally polarized incident beams. Such degrees of freedom (i.e., structural state and polarization) enable a single reconfigurable metasurface with fixed geometrical parameters to generate four distinct wide-gamut colors suitable for a wide range of applications, including tunable full-color printing and displays, information encryption, and anti-counterfeiting. © 2021, CC BY.

关键词： Phase change materials

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Corrections to "iPhantom: A Framework for Automated Creation of Individualized Computational Phantoms and its Application to CT Organ Dosimetry"

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IEEE journal of biomedical and health informatics 2022年第1期26卷 478页

作者： Wanyi Fu Shobhit Sharma Ehsan Abadi Alexandros-Stavros Iliopoulos Qi Wang Joseph Y Lo Xiaobai Sun William P Segars Ehsan Samei Department of Electrical and Computer Engineering and Carl E. Ravin Advanced Imaging Laboratories Duke University Durham NC USA Department of Physics and Carl E. Ravin Advanced Imaging Laboratories Duke University Durham NC USA Department of Computer Science Duke University Durham NC USA Computer Science and Artificial Intelligence Laboratory Massachusetts Institute of Technology Cambridge MA USA Department of Radiology the Fourth Clinical Hospital of Hebei Medical University Heibei China Departments of Electrical and Computer Engineering Biomedical Engineering Medical Physics Graduate Program and Carl E. Ravin Advanced Imaging Laboratories Duke University Durham NC USA Medical Physics Graduate Program and Radiology and the Carl E. Ravin Advanced Imaging Laboratories Departments of Biomedical Engineering Duke University Durham NC USA Carl E. Ravin Advanced Imaging Laboratories Medical Physics Graduate Program Department of Radiology Electrical and Computer Engineering Biomedical Engineering and Physics Duke University Durham NC USA

In [1], the dose estimation accuracy using the alternative baseline method under modulated tube current was not correctly calculated due to an unintentional simulation error.

关键词： Phantoms Image segmentation Computed tomography Image registration

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Performance evaluation of the high-voltage CMOS active pixel sensor AstroPix for gamma-ray space telescopes

arXiv

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arXiv 2024年

作者： Suda, Yusuke Caputo, Regina Steinhebel, Amanda L. Striebig, Nicolas Jadhav, Manoj Fukazawa, Yasushi Hashizume, Masaki Kierans, Carolyn Leys, Richard Metcalfe, Jessica Negro, Michela Perić, Ivan Perkins, Jeremy S. Shin, Taylor Tajima, Hiroyasu Violette, Daniel Nakano, Norito Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashihiroshima Hiroshima739-8526 Japan NASA Goddard Space Flight Center 8800 Greenbelt Rd GreenbeltMDMD 20771 United States 8800 Greenbelt Rd GreenbeltMDMD 20771 United States ASIC and Detector Laboratory Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 Karlsruhe Baden-WürttembergD-76344 Germany Argonne National Laboratory 9700 S. Cass Avenue LemontILIL 60439 United States Department of Physics and Astronomy Louisiana State University 202 Nicholson Hall Baton RougeLALA 70803 United States University of California Santa Cruz 1156 High Street Santa CruzCACA 95064 United States Institute for Space–Earth Environmental Research Nagoya University Furo-cho Chikusa-ku Aichi Nagoya464-8601 Japan Kobayashi-Maskawa Institute for the Origin of Particles and the Universe Nagoya University Furo-cho Chikusa-ku Aichi Nagoya464-8602 Japan

AstroPix is a novel monolithic high-voltage CMOS active pixel sensor proposed for next generation medium-energy gamma-ray observatories like the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X). For AMEGO-X AstroPix must maintain a power consumption of less than 1.5 mW/cm2 while having a pixel pitch of up to 500 µm. We developed the second and third versions of AstroPix, namely AstroPix2 and AstroPix3. AstroPix2 and AstroPix3 exhibit power consumptions of 3.4 mW/cm2 and 4.1 mW/cm2, respectively. While AstroPix2 has a pixel pitch of 250 µm, AstroPix3 achieves the desired size for AMEGO-X with a pixel pitch of 500 µm. Performance evaluation of a single pixel in an AstroPix2 chip revealed a dynamic range from 13.9 keV to 59.5 keV, with the energy resolution meeting the AMEGO-X target value (60Co source. The chip was fully operational after irradiation although a decrease in gain by approximately 4% was observed. Copyright © 2024, The Authors. All rights reserved.

关键词： CMOS integrated circuits

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Nonlinear Twistronics for EM Waves

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IEEE Transactions on Antennas and Propagation 2025年

作者： Valagiannopoulos, Constantinos Alu, Andrea National Technical University of Athens School of Electrical and Computer Engineering Athens15780 Greece City University of New York Photonics Initiative Advanced Science Research Center New YorkNY10031 United States City College of The City University of New York Department of Electrical Engineering New YorkNY10031 United States City University of New York Physics Program Graduate Center New YorkNY10016 United States

The electromagnetic (EM) interaction between two anisotropic nonlinear metasurfaces, under arbitrary rotations of their optical axes, is rigorously studied. Multistability conditions with respect to rotation angles between the two surfaces are determined and explored. The examined setup demonstrates opportunities for memory and storage since these in-plane rotations may act as continuous information carriers. The abrupt transitions of the system response, from one solution branch to the other, materialize the concept of twistronics engineering in the classical EM regime, sensitive to small angular changes. These findings can enhance the design of several photonic devices from ultra-sharp sensors and switches to analog information processors and optical memory elements. © 1963-2012 IEEE.

关键词： Optical bistability

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New type of half-metallic fully compensated ferrimagnet

arXiv

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arXiv 2021年

作者： Semboshi, S. Umetsu, Rie Y. Kawahito, Y. Akai, H. Institute for Materials Research Tohoku University 2-1-1 Katahira Sendai980-8577 Japan Center for Spintronics Research Network Tohoku University 2-1-1 Katahira Sendai980-8577 Japan Center for Science and Innovation in Spintronics 2-1-1 Katahira Sendai980-8577 Japan Advanced Science-Technology Research Program Japan Agency for Marine-Earth Science and Technology 2-15 Natsushima Yokosuka Kanagawa237-0061 Japan Department of Applied Physics Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka565-0871 Japan The Institute for Solid State Physics The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8581 Japan

Half-metallic fully compensated ferrimagnets (HM-FCFMs), a special class of half-metals exhibiting zero magnetization at absolute zero, are promising candidates for next-generation spintronics applications. For over 25 years, theoretical studies have been conducted to realize HM-FCFM materials for practical applications. Herein, we experimentally demonstrate a NiAs-type hexagonal-structured (CrFe)S compound that could serve as an HM-FCFM material. It has a half-metallic nature, with 100% spin-polarized Fermi surfaces and zero magnetization. Further, the magnetization shows a linear behavior as a function of the magnetic field below the compensation temperature of around 200 K, with high magnetic coercivity of 38 kOe at 300 K. These magnetic features are expected to contribute to a quantum leap in the application of HM-FCFM layers in spintronics devices. Copyright © 2021, The Authors. All rights reserved.

关键词： Ferrimagnetism

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Medaq api traditional ethnoscience study: Identification of chemical concept from indigenous knowledge of the Lombok people

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AIP Conference Proceedings 2022年第1期2638卷

作者： Yayuk Andayani Aliefman Hakim Aris Doyan Anak Agung Ayu Trisna Handayani 1Graduate Program of Science Education Program University of Mataram Indonesia Jl. Majapahit No. 62 Mataram Nusa Tenggara Barat 83125 Indonesia 2Chemistry Education FKIP University of Mataram Lombok West Nusa Tenggara Indonesia 3Physics Education FKIP University of Mataram Lombok West Nusa Tenggara Indonesia

The Medaq api tradition of the Lombok people, which is currently almost forgotten, has the value of local wisdom and is rich in sources of indigenous knowledge. The integration of this indigenous knowledge into chemistry learning activities has not been widely reported. One of the reasons is the difficulty of teachers in identifying chemical concepts from the community’s indigenous knowledge. Therefore, this study aims to identify chemical concepts derived from indigenous knowledge in the medaq api tradition of the Lombok people. Descriptive research on indigenous knowledge of the medaq api tradition was carried out in the North Lombok area. Interview, observation, and documentation techniques were used for data collection and then analyzed descriptively. The results showed that the chemical concepts identified in the medaq api tradition include chemical reactions, thermochemistry, organic compounds, solution, and colloids. The results of this study will contribute to the development of school chemistry teaching materials and as an effort to preserve the medaq api tradition of the Lombok community.

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Gamma-ray Bursts as Distance Indicators by a Statistical Learning Approach

arXiv

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arXiv 2024年

作者： Dainotti, Maria Giovanna Narendra, Aditya Pollo, Agnieszka Petrosian, Vahé Bogdan, Malgorzata Iwasaki, Kazunari Prochaska, Jason Xavier Rinaldi, Enrico Zhou, David National Astronomical Observatory of Japan Mitaka Tokyo181-8588 Japan The Graduate University for Advanced Studies SOKENDAI Kanagawa240-0193 Japan Space Science Institute BoulderCO80301 United States Doctoral School of Exact and Natural Sciences Jagiellonian University Krakow Poland Astronomical Observatory of Jagiellonian University Krakow Poland Warsaw Poland Department of Physics Stanford University 382 Via Pueblo Mall StanfordCA94305-4060 United States Kavli Institute for Particle Astrophysics and Cosmology Stanford University United States Department of Applied Physics Stanford University United States Department of Mathematics University of Wroclaw 50-384 Poland Department of Statistics Lund University LundSE-221 00 Sweden Center for Computational Astrophysics National Astronomical Observatory of Japan 2 Chome-21-1 Osawa Mitaka Tokyo181-8588 Japan University of California Santa Cruz 1156 High Street Santa CruzCA95064 United States Program RIKEN Saitama Wakoshi 351-0198 Japan Arizona State University 1151 S Forest Ave TempeAZ85281 United States

Gamma-ray bursts (GRBs) can be probes of the early universe, but currently, only 26% of GRBs observed by the Neil Gehrels Swift Observatory GRBs have known redshifts (z) due to observational limitations. To address this, we estimated the GRB redshift (distance) via a supervised statistical learning model that uses optical afterglow observed by Swift and ground-based telescopes. The inferred redshifts are strongly correlated (a Pearson coefficient of 0.93) with the observed redshifts, thus proving the reliability of this method. The inferred and observed redshifts allow us to estimate the number of GRBs occurring at a given redshift (GRB rate) to be 8.47-9yr−1Gpc−1 for 1.9 © 2024, CC BY.

关键词： Stars

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