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

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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

Controlled tempering of lipid concentration and microbubble shrinkage as a possible mechanism for fine-tuning microbubble size and shell properties

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arXiv 2023年

作者： Zalloum, Intesar O. Sojahrood, Amin Jafari Paknahad, Ali A. Kolios, Michael C. Tsai, Scott S.H. Karshafian, Raffi Department of Physics Toronto Metropolitan University TorontoONM5B 2K3 Canada Department of Mechanical and Industrial Engineering Toronto Metropolitan University 350 Victoria Street TorontoONM5B 2K3 Canada A Partnership Between Toronto Metropolitan University St. Michael's Hospital 209 Victoria Street TorontoONM5B 1T8 Canada Keenan Research Centre for Biomedical Science Unity Health Toronto 209 Victoria Street TorontoONM5B 1W8 Canada Graduate Program in Biomedical Engineering Toronto Metropolitan University 350 Victoria Street TorontoONM5B 2K3 Canada

The acoustic response of microbubbles (MBs) depends on their resonance frequency, which is dependent on MB size and shell properties. Monodisperse MBs with tunable shell properties are thus desirable for optimizing and controlling MB behavior in acoustics applications. By utilizing a novel microfluidic method that uses lipid concentration to control MB shrinkage, we generate monodisperse MBs of four different initial diameters at three lipid concentrations (5.6, 10.0, and 16.0 mg/mL) in the aqueous phase. Following shrinkage, we measure MB resonance frequency and determine its shell stiffness and viscosity. The study demonstrates that we can generate monodisperse MBs of specific sizes and tunable shell properties by controlling MB initial diameter and aqueous phase lipid concentration. Our results indicate that the resonance frequency increases by 180-210% with increasing lipid concentration (from 5.6 to 16.0 mg/mL) while bubble diameter is kept constant. Additionally, we find that the resonance frequency decreases by 260-300% with increasing MB final diameter (from 5 to 12 μm), while lipid concentration is held constant. For example, our results depict that the resonance frequency increases by ~195% with increasing lipid concentration from 5.6 to 16.0 mg/mL, for ~11 μm final diameter MBs. Additionally, we find that the resonance frequency decreases by ~275% with increasing MB final diameter from 5 to 12 μm, when we use a lipid concentration of 5.6 mg/mL. We also determine that MB shell viscosity and stiffness increase with increasing lipid concentration and MB final diameter, and the level of change depends on the degree of shrinkage experienced by MB. Specifically, we find that by increasing the concentration of lipids from 5.6 to 16.0 mg/mL, the shell stiffness and viscosity of ~11 μm final diameter MBs increase by ~400% and ~200 %, respectively. This study demonstrates the feasibility of fine-tuning the MB acoustic response to ultrasound by tailoring MB initial

关键词： Shrinkage

NuSTAR Observes Two Bulgeless Galaxies: No Hard X-ray AGN Detected in NGC 4178 or J0851+3926

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arXiv 2022年

作者： Pfeifle, Ryan W. Satyapal, Shobita Ricci, Claudio Secrest, Nathan J. Gliozzi, Mario Bohn, Thomas Canalizo, Gabriela Reefe, Michael A. X-ray Astrophysics Laboratory NASA Goddard Space Flight Center Code 662 GreenbeltMD20771 United States Oak Ridge Associated Universities NASA NPP Program Oak RidgeTN37831 United States Department of Physics and Astronomy George Mason University 4400 University Drive MSN 3F3 FairfaxVA22030 United States Núcleo de Astronomía de la Facultad de Ingeniería Universidad Diego Portales Av. Ejército Libertador 441 Santiago Chile Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China U.S. Naval Observatory 3450 Massachusetts Avenue NW WashingtonDC20392 United States Hiroshima Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima Hiroshima739-8526 Japan University of California Riverside Department of Physics & Astronomy 900 University Ave. RiversideCA92521 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Kavli Institute for Astrophysics and Space Research Massachusetts Institute of Technology CambridgeMA02139 United States NASA Postdoctoral Program National Science Foundation Graduate Research

The discovery over the last several decades of moderate luminosity AGNs in disk-dominated galaxies – which show no "classical" bulges – suggests that secular mechanisms represent an important growth pathway for supermassive black holes in these systems. We present new follow-up NuSTAR observations of the optically-elusive AGNs in two bulgeless galaxies, NGC 4178 and J0851+3926. NGC 4178 was originally reported as hosting an AGN based on the detection of [Ne V] mid-infrared emission detected by Spitzer, and based on Chandra X-ray imaging it has since been argued to host either a heavily obscured AGN or a supernova remnant. J0851+3926 was originally identified as an AGN based on its WISE mid-IR colors, and follow-up near-infrared spectroscopy previously revealed a hidden broad line region, offering compelling evidence for an optically-elusive AGN. Neither AGN is detected within the new NuSTAR imaging, and we derive upper limits on the hard X-ray 10-24 keV fluxes of −14 erg cm−2 s−1 and −14 erg cm−2 s−1 for the AGNs in NGC 4178 and J0851+3926, respectively. If these non-detections are due to large absorbing columns along the line of sight, the non-detections in NGC 4178 and J0851+3926 could be explained with column densities of log(NH/cm2) > 24.2 and log(NH/cm2) > 24.1, respectively. The nature of the nuclear activity in NGC 4178 remains inconclusive;it is plausible that the [Ne V] traces a period of higher activity in the past, but that the AGN is relatively quiescent now. The non-detection in J0851+3926 and multiwavelength properties are consistent with the AGN being heavily obscured. © 2022, CC BY.

关键词： Luminance

Entanglement and purification transitions in non-Hermitian quantum mechanics

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arXiv 2020年

作者： Gopalakrishnan, Sarang Gullans, Michael J. Department of Physics and Astronomy CUNY College of Staten Island Staten IslandNY10314 United States Physics Program and Initiative for the Theoretical Sciences The Graduate Center CUNY New YorkNY10016 United States Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States

A quantum system subject to continuous measurement and post-selection evolves according to a non-Hermitian Hamiltonian. We show that, as one increases the rate of post-selection, this non-Hermitian Hamiltonian can undergo a spectral phase transition. On one side of this phase transition (for weak post-selection) an initially mixed density matrix remains mixed at all times, and an initially unentangled state develops volume-law entanglement;on the other side, an arbitrary initial state approaches a unique pure state with low entanglement. We identify this transition with an exceptional point in the spectrum of the non-Hermitian Hamiltonian, at which PT symmetry is spontaneously broken. We characterize the transition as well as the nontrivial steady state that emerges at late times in the mixed phase using exact diagonalization and an approximate, analytically tractable mean-field theory;these methods yield consistent conclusions. Copyright © 2020, The Authors. All rights reserved.

关键词： Mean field theory

Electron Acceleration in Carbon Nanotubes

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arXiv 2025年

作者： Bonţoiu, Cristian Bonatto, Alexandre Apsimon, Öznur Bandiera, Laura Cavoto, Gianluca Drebot, Illya Gatti, Giancarlo Giner-Navarro, Jorge Lei, Bifeng Martín-Luna, Pablo Rago, Ilaria Pérez, Juan Rodríguez Nunes, Bruno Silveira Sytov, Alexei Valagiannopoulos, Costas Welsch, Carsten P. Xia, Guoxing Resta-López, Javier Department of Physics University of Liverpool Oxford Street LiverpoolL69 7ZE United Kingdom Graduate Program in Information Technology and Healthcare Management the Beam Physics Group Federal University of Health Sciences of Porto Alegre RS Porto Alegre90050-170 Brazil Department of Physics and Astronomy University of Manchester Oxford Road ManchesterM13 9PL United Kingdom Cockroft Institute Keckwick Lane Daresbury WarringtonWA4 4AD United Kingdom INFN Sezione di Ferrara Via Saragat 1 Ferrara44122 Italy Dipartimento di Fisica Sapienza Università di Roma Piazzale Aldo Moro 2 Roma00185 Italy INFN Sezione di Roma Piazzale Aldo Moro 2 Rome00185 Italy INFN Sezione di Milano Via G. Celoria 16 Milano20133 Italy Centro de Láseres Pulsados Building M5 Science Park Calle Adaja 8 Salamanca Villamayor37185 Spain Universidad de Valencia Paterna46071 Spain Universidad de Valencia CSIC Paterna46980 Spain Nuclear and Energy Research Institute IPEN–CNEN SP São Paulo Brazil National Technical University of Athens School of Electrical and Computer Engineering Zografou157 73 Greece Departamento de Física Aplicada y Electromagnetismo Universidad de Valencia Burjassot46100 Spain

Laser wakefield acceleration (LWFA) may achieve TeV/m gradients using high-density solid-state plasmas as accelerating media. However, the application of bulk solid materials requires attosecond laser pulses, such as X-ray lasers, to drive wakefields at these high densities. Additionally, the short wakefield wavelengths associated with solid-state plasmas greatly limit the accelerating length. An alternative approach employs 2D carbon-based nanomaterials, like graphene or carbon nanotubes (CNTs), configured into structured targets. These nanostructures are designed with voids or low-density regions to effectively reduce the overall plasma density. This reduction enables the use of longer-wavelength lasers and also extends the plasma wavelength and the acceleration length. In this study, we present, to our knowledge, the first numerical demonstration of electron acceleration via self-injection into a wakefield bubble driven by an infrared laser pulse in structured CNT targets, similar to the behavior observed in gaseous plasmas for LWFA in the nonlinear (or bubble) regime. Using the PIConGPU code, bundles of CNTs are modeled in a 3D geometry as 25 nm-thick carbon tubes with an initial density of 1022 cm−3. The carbon plasma is ionized by a three-cycle, 800 nm wavelength laser pulse with a peak intensity of 1021 W cm−2, achieving an effective plasma density of 1020 cm−3. The same laser also drives the wakefield bubble, responsible for the electron self-injection and acceleration. Simulation results indicate that fs-long electron bunches with hundreds of pC charge can be self-injected and accelerated at gradients exceeding 1 TeV/m. Both charge and accelerating gradient figures are unprecedented when compared with LWFA in gaseous plasma. © 2025, CC BY-NC-ND.

关键词： X ray lasers

High Resolution Imaging of Hg/Se Aggregates in the Brain of Wild Terrestrial Species (Small Indian Mongoose) – Insight into Intracellular Hg Detoxification

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SSRN

SSRN 2023年

作者： Devabathini, Pavani Fischer, Darrell L. Chen, Si Pattammattel, Ajith Bury, Gabriel Antipova, Olga Huang, Xiaojing Chu, Yong S. Horai, Sawako Pushkar, Yulia Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States National Synchrotron Light Source II Brookhaven National Laboratory UptonNY11973 United States XSD Argonne National Laboratory 9700 S. Cass Ave. ArgonneIL60439 United States Department of Life and Environmental Agricultural Science Tottori University Tottori680-8550 Japan Harvard Graduate Program in Biophysics Harvard 2 University HMS Campus 240/250 Longwood Avenue Seeley G. Mudd Bldg. C Room 204c BostonMA02115 United States Environmental Health Section Dept. Environment and Public Health National Institute for Minamata Disease Ministry of the Environment 4058-18 Hama Minamata City Kumamoto867-0008 Japan

Exposure to Hg in humans is highly neurotoxic. However, Hg biomagnification in marine mammals and predatory fish seems not to affect the species health. Significantly less is known about the response of wild terrestrial species to elevated environmental Hg. Elevated Hg content on par with organ level concentrations in marine mammals has been found in the liver of wild small Indian mongoose. This indicates high levels of exposure and potential biomagnification in analysed animal populations. Synchrotron X-ray fluorescence microscopy revealed significant Hg content in the mongoose brain, where micron-sized Hg-rich deposits were preferentially detected in the cells of the choroid plexus and astrocytes of the subventricular wall. Hg content in these aggregates exhibited significant spatial correlation (r ~ 0.9-0.8) with selenium (Se), suggesting the interaction of two elements. Hg aggregates do not co-localize with lysosomes. The low Hg density inside aggregates indicates diffuse Hg binding to a Se-containing biomolecule rather than much denser HgSe nanoparticles proposed to form in other species. Se K-edge XANES did not match spectra of HgSe material. Our data highlight the susceptibility of small Indian mongoose population to Hg pollution and provide evidence on the adaptation in the form of a Se-based detoxification mechanism sequestering Hg into intracellular aggregates. © 2023, The Authors. All rights reserved.

关键词： Selenium

EMPRESS. V. Metallicity Diagnostics of Galaxies over 12 + log(O/H) 6.9-8.9 Established by a Local Galaxy Census: Preparing for JWST Spectroscopy

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arXiv 2022年

作者： Nakajima, Kimihiko Ouchi, Masami Xu, Yi Rauch, Michael Harikane, Yuichi Nishigaki, Moka Isobe, Yuki Kusakabe, Haruka Nagao, Tohru Ono, Yoshiaki Onodera, Masato Sugahara, Yuma Kim, Ji Hoon Komiyama, Yutaka Lee, Chien-Hsiu Zahedy, Fakhri S. National Astronomical Observatory of Japan 2-21-1 Osawa Tokyo Mitaka181-8588 Japan Institute for Cosmic Ray Research The University of Tokyo 5-1-5 Kashiwanoha Chiba Kashiwa277-8582 Japan University of Tokyo Chiba Kashiwa277-8583 Japan Department of Astronomy Graduate School of Science The University of Tokyo 7-3-1 Hongo Tokyo Bunkyo113-0033 Japan Observatories of the Carnegie Institution for Science 813 Santa Barbara St. PasadenaCA91101 United States Department of Physics and Astronomy University College London Gower Street LondonWC1E 6BT United Kingdom Department of Astronomical Science The Graduate University for Advanced Studies SOKENDAI 2-21-1 Osawa Tokyo Mitaka181-8588 Japan Department of Physics Graduate School of Science The University of Tokyo 7-3-1 Hongo Tokyo Bunkyo113-0033 Japan Observatoire de Genève Université de Genève 51 Chemin de Pégase Versoix1290 Switzerland Research Center for Space and Cosmic Evolution Ehime University Ehime Matsuyama790-8577 Japan 650 North Aohoku Place HiloHI96720 United States Waseda Research Institute for Science and Engineering Faculty of Science and Engineering Waseda University 3-4-1 Okubo Tokyo Shinjuku169-8555 Japan Metaspace 36 Nonhyeon-ro Gangnam-gu Seoul06312 Korea Republic of 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 NSF's National Optical-Infrared Astronomy Research Laboratory 950 N Cherry Ave. TucsonAZ86719 United States

We present optical-line gas metallicity diagnostics established by the combination of local SDSS galaxies and the largest compilation of extremely metal-poor galaxies (EMPGs) including new EMPGs identified by the Subaru EMPRESS survey. A total of 103 EMPGs are included that cover a large parameter space of magnitude (Mi=-19 to-7) and Hβ equivalent width (10-600Å), i.e., wide ranges of stellar mass and star-formation rate. Using reliable metallicity measurements of the direct method for these galaxies, we derive the relationships between strong optical-line ratios and gas-phase metallicity over the range of 12+log(O/H) 6.9-8.9 corresponding to 0.02-2 solar metallicity Zo. We confirm that R23-index, ([O iii]+[O ii])/Hβ, is the most accurate metallicity indicator with the metallicity uncertainty of 0.14 dex over the range among various popular metallicity indicators. The other metallicity indicators show large scatters in the metal-poor range (. 0.1Zo). It is explained by our CLOUDY photoionization modeling that, unlike R23-index, the other metallicity indicators do not use a sum of singly and doubly ionized lines and cannot trace both low and high ionization gas. We find that the accuracy of the metallicity indicators is significantly improved, if one uses Hβ equivalent width measurements that tightly correlate with ionization states. In this work, we also present the relation of physical properties with UV-continuum slope β and ionization production rate ξionderived with GALEX data for the EMPGs, and provide local anchors of galaxy properties together with the optical-line metallicity indicators that are available in the form of ASCII table and useful for forthcoming JWST spectroscopic studies. Copyright © 2022, The Authors. All rights reserved.

关键词： Galaxies

Enhanced light-matter interaction in two-dimensional transition metal dichalcogenides

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arXiv 2021年

作者： Huang, Lujun Krasnok, Alex Alú, Andrea Yu, Yiling Neshev, Dragomir Miroshnichenko, Andrey E. School of Engineering and Information Technologies University of New South Wales CanberraACT2600 Australia 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 Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Electronic Materials Engineering Research School of Physics The Australian National University CanberraACT2601 Australia

Two dimensional (2D) transition metal dichalcogenide (TMDC) materials, such as MoS2, WS2, MoSe2, and WSe2, have received extensive attention in the past decade due to their extraordinary electronic, optical and thermal properties. 2D TMDC materials evolve from indirect bandgap semiconductors to direct bandgap semiconductors while their layer number is reduced from few layers to a monolayer limit. Consequently, there is strong photoluminescence in a monolayer (1L) TMDC due to the large quantum yield. Moreover, such monolayer semiconductors have two other exciting properties: large binding energy of excitons and valley polarization. These properties make them become ideal materials for various electronic, photonic and optoelectronic devices. However, their performance is limited by the relatively weak light-matter interactions due to their atomically thin form factor. Resonant nanophotonic structures provide a viable way to address this issue and enhance light-matter interactions in 2D TMDCs. Here, we provide an overview of this research area, showcasing relevant applications, including exotic light emission, absorption and scattering features. We start by overviewing the concept of excitons in 1L-TMDC and the fundamental theory of cavity-enhanced emission, followed by a discussion on the recent progress of enhanced light emission, strong coupling and valleytronics. The atomically thin nature of 1L-TMDC enables a broad range of ways to tune its electric and optical properties. Thus, we continue by reviewing advances in TMDC-based tunable photonic devices. Next, we survey the recent progress in enhanced light absorption over narrow and broad bandwidths using 1L or few-layer TMDCs, and their applications for photovoltaics and photodetectors. We also review recent efforts of engineering light scattering, e.g., inducing Fano resonances, wavefront engineering in 1L or few-layer TMDCs by either integrating resonant structures, such as plasmonic/Mie resonant metasurfaces, or

关键词： Monolayers

Brain activity of problem solving proccess: a systematic literarure review

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Journal of physics: Conference Series 2021年第5期1918卷

作者： E Juliyanto P Marwoto R S Iswari Wiyanto S E Nugroho B N Mindyarto Doctoral Program of Science Education Post Graduate Program Universitas Negeri Semarang Indonesia Science Education Departement Faculty of Teacher Training and Education Universitas Tidar Indonesia Departement of Physics Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia Departement of Biology Faculty of Mathematics and Natural Science Universitas Negeri Semarang Indonesia

Comprehending the problem-solving process is an effort that is no less important than teaching problem-solving skills at school. By understanding the problem-solving process, it will be easier to teach at school. Several neurological studies discuss activities in solving problems, but the scope of the discussion is narrow and in-depth. On the other hand, it requires complete information about how the problem-solving process is a complex cognitive process. This research is a systematic literature review using the PRISMA approach. The result shows that the problem-solving skills were developing based on ages of development. The effectiveness of problem-solving skills is characterized by minimal brain activity but produces the right solution. In addition, the result of the review shows that semantic ability and mathematical logic ability play an important role in a problem solving process. Getting complete problem solving process needs many parts of the brain. DLPFC and IFG are the dominant parts of the brain in the process of solving problems.

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