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37th International Cosmic Ray Conference, ICRC 2021

作者： Pan, Yue Allison, P. Archambault, S. Beatty, J.J. Beheler-Amass, M. Besson, D.Z. Beydler, M. Chen, C.H. Chen, P. Chen, Y.C. Clark, B.A. Clay, W. Connolly, A. Cremonesi, L. Dasgupta, P. Davies, J. de Kockere, S. de Vries, K.D. Deaconu, C. DuVernois, M.A. Flaherty, J. Friedman, E. Gaior, R. Hanson, J. Hanson, K. Harty, N. Hendricks, B. Hoffman, K.D. Hokanson-Fasig, B. Hong, E. Hsu, S.Y. Huang, J.J. Huang, M.-H. Hughes, K. Ishihara, A. Karle, A. Kelley, J.L. Khandelwal, R. Kim, K.-C. Kim, M.-C. Kravchenko, I. Krebs, R. Ku, Y. Kuo, C.Y. Kurusu, K. Landsman, H. Latif, U.A. Laundrie, A. Liu, T.-C. Lu, M.-Y. Madison, B. Mase, K. Meures, T. Nam, J. Nichol, R.J. Nir, G. Novikov, A. Nozdrina, A. Oberla, E. ÓMurchadha, A. Osborn, J. Pan, Y. Pfendner, C. Punsuebsay, N. Roth, J. Sandstrom, P. Seckel, D. Shiao, Y.S. Shultz, A. Smith, D. Toscano, S. Torres, J. Touart, J. van Eijndhoven, N. Varner, G.S. Vieregg, A. Wang, M.-Z. Wang, S.-H. Wang, Y.H. Wissel, S.A. Yoshida, S. Young, R. University of Delaware NewarkDE United States Dept. of Physics Center for Cosmology and AstroParticle Physics The Ohio State University ColumbusOH43210 United States Dept. of Physics Chiba University Chiba Japan Dept. of Physics University of Wisconsin-Madison MadisonWI53706 United States Dept. of Physics and Astronomy University of Kansas LawrenceKS66045 United States Moscow Engineering Physics Institute Moscow Russia Dept. of Physics Grad. Inst. of Astrophys. Leung Center for Cosmology and Particle Astrophysics National Taiwan University Taipei Taiwan Dept. of Physics and Astronomy Michigan State University East LansingMI48824 United States Dept. of Physics Enrico Fermi Institue Kavli Institute for Cosmological Physics University of Chicago ChicagoIL60637 United States Dept. of Physics and Astronomy University College London London United Kingdom Université Libre de Bruxelles Science Faculty CP230 BrusselsB-1050 Belgium Vrije Universiteit Brussel Brussels Belgium Dept. of Physics University of Maryland College ParkMD20742 United States Dept. Physics and Astronomy Whittier College WhittierCA90602 United States Dept. of Physics University of Delaware NewarkDE19716 United States Center for Multi-Messenger Astrophysics Institute for Gravitation and the Cosmos Pennsylvania State University University ParkPA16802 United States Dept. of Physics Pennsylvania State University University ParkPA16802 United States Dept. of Physics and Astronomy University of Nebraska LincolnNE68588 United States Weizmann Institute of Science Rehovot Israel Dept. of Physics and Astronomy Denison University GranvilleOH43023 United States Dept. of Physics and Astronomy University of Hawaii HI96822 United States Dept. of Astronomy and Astrophysics Pennsylvania State University University ParkPA16802 United States Physics Dept. California Polytechnic State University San Luis ObispoCA93407 United States

The Askaryan Radio Array (ARA) is an ultra-high energy (UHE) neutrino (Eν > 1017 eV) detector at South Pole. ARA aims to utilize radio signals detected from UHE neutrino interactions in the glacial ice to infer properties about the interaction vertex as well as the incident neutrino. To retrieve these properties from experiment data, the first step is to extract timing, amplitude and frequency information from waveforms of different antennas buried in the deep ice. These features can then be utilized in a neural network to reconstruct the neutrino interaction vertex position, incoming neutrino direction and shower energy. So far, vertex can be reconstructed through interferometry while neutrino reconstruction is still under investigation. Here I will present a solution based on multi-task deep neural networks which can perform reconstruction of both vertex and incoming neutrinos with a reasonable precision. After training, this solution is capable of rapid reconstructions (e.g. 0.1 ms/event compared to 10000 ms/event in a conventional routine) useful for trigger and filter decisions, and can be easily generalized to different station configurations for both design and analysis purposes. © Copyright owned by the author(s).

关键词： Neutrons

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Measurement of the neutron capture cross sections of rhenium up to stellar s- and r-process temperatures at the China Spallation Neutron Source Back-n facility

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Physical Review Research 2024年第1期6卷 013225-013225页

作者： Gaole Yang Zhendong An Wei Jiang Xiankai Li Weiwei Qiu Zhengfa Liao Ziyue Zhuang Xiaoping Zhang Shengli Chen Chenchen Guo Erxi Xiao Xiao Fang Xinxiang Li Hongwei Wang Xinrong Hu Bing Jiang Wenqing Shen Jincheng Wang Jie Ren Xichao Ruan Dexin Wang Su-Yalatu Zhang Wen Luo Zhichao Zhu Haoyang Lan Zongwei Cao Xu Ma Yingdu Liu Pusen Wang Yi Yang Ping Su Xiangai Deng Wanbing He Yugang Ma Chunwang Ma Yuting Wang Zhitao Dai Ertao Li Pengqin He RenGuang Tang Tao Zhou Jing Wang Han Yi Yue Zhang Yonghao Chen Ruirui Fan Keqing Gao Qiang Li Kang Sun Zhixin Tan Minhao Gu Hantao Jing Jingyu Tang Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China School of Physics and Astronomy Sun Yat-sen University Zhuhai 519082 China State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Macau 999078 China CNSA Macau Center for Space Exploration and Science Macau 999078 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Spallation Neutron Source Science Center Dongguan 523803 China School of Nuclear Science and Technology University of South China Hengyang 421001 China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University Zhuhai 519082 China University of Chinese Academy of Sciences Beijing 100049 China Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201210 China Key Laboratory of Nuclear Data China Institute of Atomic Energy Beijing 102413 China College of Mathematics and Physics Inner Mongolia Minzu University Tongliao 028000China Institute of Nuclear Physics Inner Mongolia Minzu University Tongliao 028000 China Shool of Materials Science and Engineering Xiangtan University Xiangtan 411100 China Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 China Institute of Particle and Nuclear Physics Henan Normal University Xinxiang 453007 China School of Physics Henan Normal University Xinxiang 453007 China Shenzhen Center Cancer hospital Chinese Academy of Medical Sciences Shenzhen 518100 China Institute for Advanced Study in Nuclear Energy and Safety College of Physics and Optoelectronic Engineering Shenzhen University Shenzhen 518060 China School of Nuclear Science and Technology University of Science and Technology of China Hefei 230027 China

The neutron capture measurement of natural rhenium was performed with the time-of-flight technique at the Back-n facility of the China Spallation Neutron Source in the energy range from 1 to 500 eV of the resolved resonance region (RRR) and from 5 to 400 keV in the unresolved resonance region (URR). Prompt γ-rays originating from neutron-induced capture events were detected by four C6D6 detectors. The pulse height weighting technique and the double-bunch unfolding method based on the Bayesian theory were used in the data analysis. To obtain reliable measurement results, background subtraction, normalization, and corrections were carefully considered. The multilevel R-matrix Bayesian code SAMMY was used to extract the resonance parameters in the RRR. An absence of resonance near 392 eV is observed in our measurement, which has been observed in previous works. The average cross sections in the URR of natural rhenium relative to Au197 were obtained in logarithmical equidistant energy bins with 20 bins per energy decade. The talys code was used to describe the average cross sections in the URR; the Maxwellian-averaged cross sections (MACSs) of Re185 and Re187 are given from kT=5 to 100 keV. At a thermal energy of kT=30 keV, the MACS value for Re185 (1469±127 mb) is in good agreement with the Karlsruhe Astrophysical database of Nucleosynthesis in Stars (KADoNIS) recommended value (1535±62 mb) within the error bars. By contrast, the value of 1361±118 mb for Re187 shows a discrepancy with the KADoNiS recommended value (1160±57 mb).

关键词： Nuclear astrophysics Nuclear reaction rates Nuclear reactions Radiative capture Resonance reactions r process s process 150 ≤ A ≤ 189 Nuclear data analysis & compilation

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Detecting axion dark matter beyond the magnetoquasistatic approximation

arXiv

引用

arXiv 2022年

作者： Benabou, Joshua N. Foster, Joshua W. Kahn, Yonatan Safdi, Benjamin R. Salemi, Chiara P. Berkeley Center for Theoretical Physics University of California BerkeleyCA94720 United States Theoretical Physics Group Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Center for Theoretical Physics Massachusetts Institute of Technology CambridgeMA02139 United States Illinois Center for Advanced Studies of the Universe Department of Physics University of Illinois Urbana-Champaign UrbanaIL61801 United States Laboratory of Nuclear Science Massachusetts Institute of Technology CambridgeMA02139 United States Kavli Institute for Particle Astrophysics and Cosmology Stanford University StanfordCA94305 United States Stanford Linear Accelerator Center Menlo ParkCA94025 United States

A number of proposals have been put forward for detecting axion dark matter (DM) with grand unification scale decay constants that rely on the conversion of coherent DM axions to oscillating magnetic fields in the presence of static, laboratory magnetic fields. Crucially, such experiments - including ABRACADABRA - have to-date worked in the limit that the axion Compton wavelength is larger than the size of the experiment, which allows one to take a magnetoquasistatic (MQS) approach to modeling the axion signal. We use finite element methods to solve the coupled axion-electromagnetism equations of motion without assuming the MQS approximation. We show that the MQS approximation becomes a poor approximation at frequencies two orders of magnitude lower than the naive MQS limit. Radiation losses diminish the quality factor of an otherwise high-Q resonant readout circuit, though this may be mitigated through shielding and minimizing lossy materials. Additionally, self-resonances associated with the detector geometry change the reactive properties of the pickup system, leading to two generic features beyond MQS: there are frequencies that require an inductive rather than capacitive tuning to maintain resonance, and the detector itself becomes a multi-pole resonator at high frequencies. Accounting for these features, competitive sensitivity to the axion-photon coupling may be extended well beyond the naive MQS limit. Copyright © 2022, The Authors. All rights reserved.

关键词： Equations of motion

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Cosmological Forecast of the Void Size Function Measurement from the CSST Spectroscopic Survey

arXiv

引用

arXiv 2024年

作者： Song, Yingxiao Xiong, Qi Gong, Yan Deng, Furen Chan, Kwan Chuen Chen, Xuelei Guo, Qi Han, Jiaxin Li, Guoliang Li, Ming Liu, Yun Luo, Yu Pei, Wenxiang Wei, Chengliang National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing100012 China Yuquan Road NO.19A Beijing100049 China Science Center for China’s Space Survey Telescope National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Beijing100101 China Department of Physics College of Sciences Northeastern University Shenyang110819 China Centre for High Energy Physics Peking University Beijing100871 China School of Physics and Astronomy Sun Yat-Sen University 2 Daxue Road Tangjia Zhuhai519082 China CSST Science Center for the Guangdong-Hongkong-Macau Greater Bay Area SYSU Zhuhai519082 China Department of Astronomy School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Shanghai200240 China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai200240 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China

Void size function (VSF) contains the information of the cosmic large-scale structure (LSS), and can be used to derive the properties of dark energy and dark matter. We predict the VSFs measured from the spectroscopic galaxy survey operated by China’s Space Survey Telescope (CSST), and study the strength of cosmological constraint. We employ a high-resolution Jiutian simulation to get CSST galaxy mock samples based on an improved semi-analytical model. We identify voids from this galaxy catalog using the watershed algorithm without assuming a spherical shape, and estimate the VSFs at different redshift bins from z = 0.5 to 1.1. We propose a void selection method based on the ellipticity, and assume the void linear underdensity threshold δv in the theoretical model is redshift-dependent and set it as a free parameter in each redshift bin. The Markov Chain Monte Carlo (MCMC) method is adopted to implement the constraints on the cosmological and void parameters. We find that the CSST VSF measurement can constrain the cosmological parameters to a few percent level. The best-fit values of δv are ranging from ∼ -0.4 to -0.1 as the redshift increases from 0.5 to 1.1, which has a distinct difference from the theoretical calculation with δv -2.7 assuming the spherical evolution and using particles as tracer. Our method can provide a good reference for the void identification and selection in the VSF analysis of the spectroscopic galaxy surveys. Copyright © 2024, The Authors. All rights reserved.

关键词： Dark energy

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Capping the positivity cone: Dimension-8 Higgs operators in the SMEFT

arXiv

引用

arXiv 2023年

作者： Chen, Qing Mimasu, Ken Wu, Tong Arthur Zhang, Guo-Dong Zhou, Shuang-Yong Interdisciplinary Center for Theoretical Study University of Science and Technology of China Anhui Hefei230026 China Peng Huanwu Center for Fundamental Theory Anhui Hefei230026 China School of Physics and Astronomy University of Southampton Highfield SouthamptonS017 1BJ United Kingdom Theoretical Particle Physics and Cosmology Group Department of Physics King's College London LondonWC2R 2LS United Kingdom School of The Gifted Young University of Science and Technology of China Anhui Hefei230026 China PITT PACC Department of Physics and Astronomy University of Pittsburgh 3941 O'Hara St. PittsburghPA15260 United States Theoretical Physics Blackett Laboratory Imperial College LondonSW7 2AZ United Kingdom

SMEFT Wilson coefficients are subject to various positivity bounds in order to be consistent with the fundamental principles of S-matrix. Previous bounds on dimension-8 SMEFT operators have been obtained using the positivity part of UV partial wave unitarity and form a (projective) convex cone. We derive a set of linear UV unitarity conditions that go beyond positivity and are easy to implement in an optimization scheme with dispersion relations in a multi-field EFT. Using Higgs scattering as an example, we demonstrate how to obtain closed bounds in the space of the three relevant dimension-8 coefficients, making use of the UV unitarity conditions as well as so-called null constraints that arise from full crossing symmetry. Specifically, we show that they are bounded by inequalities schematically going like C 2). We compare the newly obtained upper bounds with the traditional perturbative unitarity bounds from within the EFT, and discuss some phenomenological implications of the two-sided positivity bounds in the context of experimental probes of Vector Boson Scattering. Copyright © 2023, The Authors. All rights reserved.

关键词： Cones

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Performance of LHAASO-WCDA and observation of the Crab Nebula as a standard candle

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Chinese physics C 2021年第8期45卷 166-181页

作者： F.Aharonian Q.An Axikegu L.X.Bai Y.X.Bai Y.W.Bao D.Bastieri X.J.Bi Y.J.Bi H.Cai J.T.Cai Z.Cao Z.Cao J.Chang J.F.Chang X.C.Chang B.M.Chen J.Chen L.Chen L.Chen L.Chen M.J.Chen M.L.Chen Q.H.Chen S.H.Chen S.Z.Chen T.L.Chen X.L.Chen Y.Chen N.Cheng Y.D.Cheng S.W.Cui X.H.Cui Y.D.Cui B.Z.Dai H.L.Dai Z.G.Dai Danzengluobu D.della Volpe B.D'Ettorre Piazzoli X.J.Dong J.H.Fan Y.Z.Fan Z.X.Fan J.Fang K.Fang C.F.Feng L.Feng S.H.Feng Y.L.Feng B.Gao C.D.Gao Q.Gao W.Gao M.M.Ge L.S.Geng G.H.Gong Q.B.Gou M.H.Gu J.G.Guo X.L.Guo Y.Q.Guo Y.Y.Guo Y.A.Han H.H.He H.N.He J.C.He S.L.He X.B.He Y.He M.Heller Y.K.Hor C.Hou X.Hou H.B.Hu S.Hu S.C.Hu X.J.Hu D.H.Huang Q.L.Huang W.H.Huang X.T.Huang Z.C.Huang F.Ji X.L.Ji H.Y.Jia K.Jiang Z.J.Jiang C.Jin D.Kuleshov K.Levochkin B.B.Li C.Li C.Li F.Li H.B.Li H.C.Li H.Y.Li J.Li K.Li W.L.Li X.Li X.Li X.R.Li Y.Li Y.Z.Li Z.Li Z.Li E.W.Liang Y.F.Liang S.J.Lin B.Liu C.Liu D.Liu H.Liu H.D.Liu J.Liu J.L.Liu J.S.Liu J.Y.Liu M.Y.Liu R.Y.Liu S.M.Liu W.Liu Y.N.Liu Z.X.Liu W.J.Long R.Lu H.K.Lv B.Q.Ma L.L.Ma X.H.Ma J.R.Mao A.Masood W.Mitthumsiri T.Montaruli Y.C.Nan B.Y.Pang P.Pattarakijwanich Z.Y.Pei M.Y.Qi B.Q.Qiao D.Ruffolo V.Rulev A.Saiz L.Shao O.Shchegolev X.D.Sheng J.R.Shi H.C.Song Yu.V.Stenkin V.Stepanov Q.N.Sun X.N.Sun Z.B.Sun P.H.T.Tam Z.B.Tang W.W.Tian B.D.Wang C.Wang H.Wang H.G.Wang J.C.Wang J.S.Wang L.P.Wang L.Y.Wang R.N.Wang W.Wang W.Wang X.G.Wang X.J.Wang X.Y.Wang Y.D.Wang Y.J.Wang Y.P.Wang Z.Wang Z.Wang Z.H.Wang Z.X.Wang D.M.Wei J.J.Wei Y.J.Wei T.Wen C.Y.Wu H.R.Wu S.Wu W.X.Wu X.F.Wu S.Q.Xi J.Xia J.J.Xia G.M.Xiang G.Xiao H.B.Xiao G.G.Xin Y.L.Xin Y.Xing D.L.Xu R.X.Xu L.Xue D.H.Yan C.W.Yang F.F.Yang J.Y.Yang L.L.Yang M.J.Yang R.Z.Yang S.B.Yang Y.H.Yao Z.G.Yao Y.M.Ye L.Q.Yin N.Yin X.H.You Z.Y.You Y.H.Yu Q.Yuan H.D.Zeng T.X.Zeng W.Zeng Z.K.Zeng M.Zha X.X.Zhai B.B.Zhang H.M.Zhang H.Y.Zhang J.L.Zhang J.W.Zhang L.Zhang L.Zhang L.X.Zhang P.F.Zhang P.P.Zhang R.Zhang S.R.Zhang S.S.Zhang X.Zhang X.P.Zhang Y.Zhang Y.Zhang Y.F.Zhang Y.L.Zhang B.Zhao J.Zhao L.Zhao L.Z.Zhao S.P.Zhao F.Zheng Y.Zheng B.Zhou H.Zhou J.N.Zhou Key Laboratory of Particle Astrophyics&Experimental Physics Division&Computing Center Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China TIANFU Cosmic Ray Research Center ChengduSichuanChina State Key Laboratory of Particle Detection and Electronics China University of Science and Technology of China Hefei 230026China Department of Engineering Physics Tsinghua UniversityBeijing 100084China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China National Space Science Center Chinese Academy of SciencesBeijing 100190China School of Physics Peking UniversityBeijing 100871China Center for Astrophysics Guangzhou UniversityGuangzhou 510006China School of Physics and Astronomy&School of Physics(Guangzhou) Sun Yat-sen UniversityZhuhai 519082China School of Physical Science and Technology Guangxi UniversityNanning 530004China Hebei Normal University Shijiazhuang 050024China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China Institute of Frontier and Interdisciplinary Science Shandong UniversityQingdao 266237China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryChinese Academy of SciencesShanghai 200030China Tsung-Dao Lee Institute&School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China School of Physical Science and Technology&School of Information Science and Technology Southwest Jiaotong UniversityChengdu 610031China College of Physics Sichuan UniversityChengdu 610065China Key Laboratory of Cosmic Rays(Tibet University) Ministry of EducationLhasa 850000China School of Physics and Technology Wuhan UniversityWuhan 430072China School of Physics and Astronomy Yunnan University

The first Water Cherenkov detector of the LHAASO experiment(WCDA-1)has been operating since April *** data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard *** WCDA-1 achieves a sensitivity of 65 mCU per year,with a statistical threshold of 5 *** accomplish this,a 97.7%cosmic-ray background rejection rate around 1 TeV and 99.8%around 6 TeV with an ap proximate photon acceptance of 50%is achieved after applying an algorithm to separate gamma-induced *** angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45°at 1 TeV and better than 0.2°above 6 TeV,with a pointing accuracy better than 0.05°.These values all match the design *** energy resolution is found to be 33%for gamma rays around 6 *** spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.

关键词： LHAASO-WCDA Crab Nebula angular resolution spectral energy distribution

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Establishing the Non-Primordial Origin of Black Hole-Neutron Star Mergers

arXiv

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arXiv 2021年

作者： Sasaki, Misao Takhistov, Volodymyr Vardanyan, Valeri Zhang, Ying-Li UTIAS The University of Tokyo Chiba 277-8583 Japan Center for Gravitational Physics Yukawa Institute for Theoretical Physics Kyoto University Kyoto606-8502 Japan Leung Center for Cosmology and Particle Astrophysics National Taiwan University Taipei10617 Taiwan School of Physics Science and Engineering Tongji University Shanghai200092 China Institute for Advanced Study of Tongji University Shanghai200092 China Center for Gravitation and Cosmology YangZhou University Yangzhou225009 China

Primordial black holes (PBHs) from the early Universe constitute an attractive dark matter candidate. First detections of black hole-neutron star (BH-NS) candidate gravitational wave events by the LIGO/Virgo collaboration, GW200105 and GW200115, already prompted speculations about non-astrophysical origin. We analyze, for the first time, the total volumetric merger rates of PBH-NS binaries formed via two-body gravitational scattering, finding them to be subdominant to the astrophysical BH-NS rates. In contrast to binary black holes, a significant fraction of which can be of primordial origin, either formed in dark matter halos or in the early Universe, PBH-NS rates cannot be significantly enhanced by contributions preceding star formation. Our findings imply that the identified BH-NS events are of astrophysical origin, even when PBH-PBH events significantly contribute to the GW observations. © 2021, CC BY.

关键词： Black holes

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The Milky Way bar potential constrained by the kinematics of SiO maser stars in BAaDE Survey

arXiv

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arXiv 2024年

作者： Xia, Tian-Ye Shen, Juntai Li, Zhi Feng, Huaijin Sjouwerman, Loránt O. Pihlström, Ylva M. Lewis, Megan O. Stroh, Michael C. Department of Astronomy School of Physics and Astronomy Shanghai Jiao Tong University 800 Dongchuan Road Shanghai200240 China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai200240 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Shanghai Key Lab for Astrophysics Shanghai Normal University 100 Guilin Road Shanghai200234 China Department of Astronomy School of Physics and Astronomy Shanghai Jiao Tong University 800 Dongchuan Road Shanghai200240 China National Radio Astronomy Observatory Pete V. Domenici Science Operations Center Operations Center SocorroNM87801 United States Department of Physics and Astronomy The University of New Mexico AlbuquerqueNM87131 United States Leiden University Leiden Observatory Leiden2300RA Netherlands Northwestern University Center for Interdisciplinary Exploration and Research in Astrophysics EvanstonIL60201 United States

We introduce a novel method that utilizes the longitude-velocity (l − v) envelope to constrain the Milky Way (MW) bar potential. Previous work (Habing 2016) used the l − v diagram to explain the distribution of the observed high-velocity stars. We successfully reproduce their results, but find that their method is limited to only one single type of periodic orbits. In contrast, we propose that the l − v envelope provides much more comprehensive constraints. We compare the properties of test particles in the Portail et al. (2017) MW potential model (P17) with the observed SiO maser stars from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey. We find that the l − v envelope generated by the bar potential demonstrates reasonable agreement with the observational data, albeit with slight discrepancies near the Galactic center. The inconsistencies suggest that the P17 potential yields a lower central rotation curve, a slightly larger quadrupole strength, or a possibly underestimated pattern speed. We also adopt an updated version of the P17 potential with a modified central mass component (CMC) proposed by Hunter et al. (2024) (H24). The fitting of the l − v envelope suggests that the H24 potential does not completely address the existing challenges and may hint at a possible underestimation of the central bar mass. Our study demonstrates that the l − v envelope can be used as a valuable tool for constraining the Galactic potential and provides insights into the Milky Way bar potential. © 2024, CC0.

关键词： Kinematics

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Deep Learning Voigt Profiles I. Single-Cloud Doublets

arXiv

引用

arXiv 2023年

作者： Stemock, Bryson Churchill, Christopher W. Lee, Avery Hassan, Sultan Doughty, Caitlin Ochoa, Rogelio Department of Astronomy New Mexico State University Las CrucesNM88003 United States Department of Computer Science New Mexico State University Las CrucesNM88003 United States Center for Cosmology and Particle Physics Department of Physics New York University 726 Broadway New YorkNY10003 United States Center for Computational Astrophysics Flatiron Institute 162 5th Ave New YorkNY10010 United States Department of Physics & Astronomy University of the Western Cape Cape Town7535 South Africa Leiden Observatory Leiden University PO Box 9513 Leiden2300 RA Netherlands

Voigt profile (VP) decomposition of quasar absorption lines is key to studying intergalactic gas and the baryon cycle governing the formation and evolution of galaxies. The VP velocities, column densities, and Doppler b parameters inform us of the kinematic, chemical, and ionization conditions of these astrophysical environments. A drawback of traditional VP fitting is that it can be human-time intensive. With the coming next generation of large all-sky survey telescopes with multi-object high-resolution spectrographs, the time demands will significantly outstrip our resources. Deep learning pipelines hold the promise to keep pace and deliver science digestible data products. We explore the application of deep learning convolutional neural networks (CNNs) for predicting VP fitted parameters directly from the normalized pixel flux values in quasar absorption line profiles. A CNN was applied to 56 single-component Mg II λλ2796, 2803 doublet absorption line systems observed with HIRES and UVES (R = 45, 000). The CNN predictions were statistically indistinct from a traditional VP fitter. The advantage is that once trained, the CNN processes systems ∼ 105 times faster than a human expert VP fitting profiles by hand. Our pilot study shows that CNNs hold promise to perform bulk analysis of quasar absorption line systems in the future. Copyright © 2023, The Authors. All rights reserved.

关键词： Galaxies

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Dimensionless machine learning: Imposing exact units equivariance

arXiv

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arXiv 2022年

作者： Villar, Soledad Yao, Weichi Hogg, David W. Blum-Smith, Ben Dumitrascu, Bianca Department of Applied Mathematics and Statistics Johns Hopkins University Mathematical Institute for Data Science Johns Hopkins University United States Department of Technology Operations and Statistics New York University United States Center for Cosmology and Particle Physics Department of Physics New York University Max-Planck-Institut für Astronomie Flatiron Institute Division of the Simons Foundation United States Department of Applied Mathematics and Statistics Johns Hopkins University United States Department of Computer Science and Technology Cambridge University United Kingdom

Units equivariance (or units covariance) is the exact symmetry that follows from the requirement that relationships among measured quantities of physics relevance must obey self-consistent dimensional scalings. Here, we express this symmetry in terms of a (non-compact) group action, and we employ dimensional analysis and ideas from equivariant machine learning to provide a methodology for exactly units-equivariant machine learning: For any given learning task, we first construct a dimensionless version of its inputs using classic results from dimensional analysis, and then perform inference in the dimensionless space. Our approach can be used to impose units equivariance across a broad range of machine learning methods which are equivariant to rotations and other groups. We discuss the in-sample and out-of-sample prediction accuracy gains one can obtain in contexts like symbolic regression and emulation, where symmetry is important. We illustrate our approach with simple numerical examples involving dynamical systems in physics and ecology. Copyright © 2022, The Authors. All rights reserved.

关键词： Dynamical systems

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