Journal
ASTROPHYSICAL JOURNAL LETTERS
Volume 930, Issue 2, Pages -Publisher
IOP Publishing Ltd
DOI: 10.3847/2041-8213/ac6428
Keywords
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Categories
Funding
- National Science Foundation [OISE-1743747, AST1816420, AST-1716536, AST-1440254, AST-1935980]
- Black Hole Initiative - John Templeton Foundation
- Gordon and Betty Moore Foundation
- NASA Hubble Fellowship - Space Telescope Science Institute [HST-HF251431.001-A]
- NASA [NAS5-26555]
- Academy of Finland [274477, 284495, 312496, 315721]
- Agencia Nacional de Investigacion y Desarrollo (ANID), Chile [NCN19_058]
- Fondecyt [3190878]
- Alexander von Humboldt Stiftung
- Alfred P. Sloan Research Fellowship
- Allegro
- European ALMA Regional Centre node in the Netherlands
- NL astronomy research network NOVA
- astronomy institute of the University of Amsterdam
- astronomy institute of the Leiden University
- astronomy institute of the Radboud University
- China Scholarship Council
- Consejo Nacional de Ciencia y Tecnologia (CONACYT, Mexico) [U0004-246083, U0004-259839, F0003-272050, M0037-279006, F0003-281692, 104497, 275201, 263356]
- Delaney Family via the Delaney Family John A. Wheeler Chair at Perimeter Institute
- Direccion General de Asuntos del Personal Academico-Universidad Nacional Autonoma de Mexico (DGAPA-UNAM) [IN112417, IN112820]
- European Research Council Synergy Grant BlackHoleCam: Imaging the Event Horizon of Black Holes [610058]
- Generalitat Valenciana postdoctoral grant [APOSTD/2018/177]
- GenT Program [CIDEGENT/2018/021]
- MICINN Research Project [PID2019-108995GB-C22]
- European Research Council [884631]
- Istituto Nazionale di Fisica Nucleare (INFN) sezione di Napoli, iniziative specifiche TEONGRAV
- Dutch National Supercomputers, Cartesius and Snellius (NWO) [2021.013]
- International Max Planck Research School for Astronomy and Astrophysics at the Universities of Bonn and Cologne
- DFG research grant Jet physics on horizon scales and beyond [FR 4069/2-1]
- Joint Princeton/Flatiron Postdoctoral Fellowship
- Joint Columbia/Flatiron Postdoctoral Fellowship
- Simons Foundation
- Japanese Government (Monbukagakusho: MEXT) Scholarship
- Japan Society for the Promotion of Science (JSPS) [JP17J08829]
- Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS) [QYZDJ-SSW-SLH057, QYZDJ-SSW-SYS008, ZDBS-LY-SLH011]
- Leverhulme Trust Early Career Research Fellowship
- Max-Planck-Gesellschaft (MPG)
- Max Planck Partner Group of the MPG
- CAS
- MEXT/JSPS KAKENHI [18KK0090, JP21H01137, JP18H03721, 18K03709, 18H01245, 25120007]
- Malaysian Fundamental Research Grant Scheme (FRGS) [FRGS/1/2019/STG02/UM/02/6]
- MIT International Science and Technology Initiatives (MISTI) Funds
- Ministry of Science and Technology (MOST) of Taiwan [103-2119-M-001-010-MY2, 105-2112-M-001-025MY3, 105-2119-M-001-042, 106-2112-M-001-011, 106-2119M-001-013, 106-2119-M-001-027, 106-2923-M-001-005, 1072119-M-001-017, 107-2119-M-001-020, 107-2119-M-001-041, 107-2119-M-110-005, 107-2923-M-001-009]
- Ministry of Education (MoE) of Taiwan Yushan Young Scholar Program
- Physics Division, National Center for Theoretical Sciences of Taiwan
- National Aeronautics and Space Administration (NASA, Fermi Guest Investigator grant) [80NSSC20K1567]
- National Aeronautics and Space Administration (NASA Astrophysics Theory Program) [80NSSC20K0527]
- National Aeronautics and Space Administration (NASA NuSTAR award) [80NSSC20K0645]
- National Institute of Natural Sciences (NINS) of Japan
- National Key Research and Development Program of China [2016YFA0400704, 2016YFA0400702]
- National Science Foundation (NSF) [AST-0096454, AST-0352953, AST-0521233, AST0705062, AST-0905844, AST-0922984, AST-1126433, AST1140030, DGE-1144085, AST-1207704, AST-1207730, AST1207752, MRI-1228509, OPP-1248097, AST-1310896, AST1555365, AST-1615796, AST-1715061, AST-1716327, AST1903847, AST-2034306]
- Natural Science Foundation of China [11650110427, 10625314, 11721303, 11725312, 11933007, 11991052, 11991053]
- NWO grant [OCENW. KLEIN.113]
- China Postdoctoral Science Foundation [2020M671266]
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- National Youth Thousand Talents Program of China
- National Research Foundation of Korea [NRF2015H1A2A1033752, 2015-R1D1A1A01056807, NRF-2015H1D3A1066561, 2019R1F1A1059721]
- Netherlands Organization for Scientific Research (NWO) VICI award [639.043.513]
- Spinoza Prize [SPI 78-409]
- New Scientific Frontiers with Precision Radio Interferometry Fellowship - South African Radio Astronomy Observatory (SARAO)
- Swedish Research Council [2017-00648]
- Government of Canada through the Department of Innovation, Science and Economic Development
- Province of Ontario through the Ministry of Research, Innovation and Science)
- Spanish Ministerio de Ciencia e Innovaci-n [PGC2018-098915-B-C21, AYA2016-80889-P, PID2019108995GB-C21, PID2020-117404GB-C21]
- State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award [SEV-2017-0709]
- Toray Science Foundation
- the Consejeria de Economia, Conocimiento, Empresas y Universidad of the Junta de Andalucia [P18-FR-1769]
- Consejo Superior de Investigaciones Cientificas [2019AEP112]
- M2FINDERS project - European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme [101018682]
- US Department of Energy (USDOE) through the Los Alamos National Laboratory [89233218CNA000001]
- European Union's Horizon 2020 research and innovation program [730562]
- Shanghai Pilot Program for Basic Research, Chinese Academy of Science, Shanghai Branch [JCYJ-SHFY-2021-013]
- ALMA North America Development Fund
- Academia Sinica
- Chandra [DD7-18089X, TM6-17006X]
- GenT Program (Generalitat Valenciana) [CIDEGENT/2018/021]
- Extreme Science and Engineering Discovery Environment (XSEDE) - NSF [ACI-1548562]
- CyVerse - NSF [DBI-0735191, DBI-1265383, DBI-1743442]
- Swedish Research Council (VR)
- Virtual Institute of Accretion (VIA) postdoctoral fellowships from the Netherlands Research School for Astronomy (NOVA)
- Smithsonian Institution
- Science and Technologies Facility Council (UK)
- Basic Science Research Program through the National Research Foundation of Korea (NRF) - Ministry of Education [NRF-2021R1A6A3A01086420]
- CNRS (Centre National de la Recherche Scientifique, France)
- MPG (Max-Planck-Gesellschaft, Germany)
- IGN (Instituto Geogrifico Nacional, Spain)
- State of Arizona
- NSF
- NASA through the NASA Hubble Fellowship [HST-HF2ers]
- Space Telescope Science Institute
- ' Ministry of Science and Technology (MOST) of Taiwan' [108-2112-M-001048, 108-2112-M-001-051, 108-2923-M-001-002, 109-2112-M001-025, 109-2124-M-001-005, 109-2923-M-001-001, 110-2112M-003-007-MY2, 110-2112-M-001-033, 110-2124-M-001-007, 110-2923-M-001-001]
- National Research Foundation of Korea [2019R1F1A1059721] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
- European Research Council (ERC) [101018682, 884631] Funding Source: European Research Council (ERC)
Ask authors/readers for more resources
The Event Horizon Telescope observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center and found its variability on short timescales of up to 1 minute at millimeter wavelengths. The spectral energy distribution of Sgr A* is flat at 220 GHz, indicating low optical depth for the event horizon scale source.
The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in the Galactic Center on 2017 April 5-11 in the 1.3 mm wavelength band. At the same time, interferometric array data from the Atacama Large Millimeter/submillimeter Array and the Submillimeter Array were collected, providing Sgr A* light curves simultaneous with the EHT observations. These data sets, complementing the EHT very long baseline interferometry, are characterized by a cadence and signal-to-noise ratio previously unattainable for Sgr A* at millimeter wavelengths, and they allow for the investigation of source variability on timescales as short as a minute. While most of the light curves correspond to a low variability state of Sgr A*, the April 11 observations follow an X-ray flare and exhibit strongly enhanced variability. All of the light curves are consistent with a red-noise process, with a power spectral density (PSD) slope measured to be between -2 and -3 on timescales between 1 minute and several hours. Our results indicate a steepening of the PSD slope for timescales shorter than 0.3 hr. The spectral energy distribution is flat at 220 GHz, and there are no time lags between the 213 and 229 GHz frequency bands, suggesting low optical depth for the event horizon scale source. We characterize Sgr A*'s variability, highlighting the different behavior observed just after the X-ray flare, and use Gaussian process modeling to extract a decorrelation timescale and a PSD slope. We also investigate the systematic calibration uncertainties by analyzing data from independent data reduction pipelines.
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