Unprecedented Near-infrared Brightness and Variability of Sgr A∗
The electromagnetic counterpart to the Galactic center supermassive black hole, Sgr A∗, has been observed in the near-infrared for over 20 yr and is known to be highly variable. We report new Keck Telescope observations showing that Sgr A∗ reached much brighter flux levels in 2019 than ever measured...
| Autores: | , , , , , , , , , , , , |
|---|---|
| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/202063 |
| Acceso en línea: | http://hdl.handle.net/10261/202063 |
| Access Level: | acceso abierto |
| Palabra clave: | Supermassive black holes Low-luminosity active galactic nuclei Near infrared astronomy Galactic center |
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| dc.title.none.fl_str_mv |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| title |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| spellingShingle |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ Do, T. Supermassive black holes Low-luminosity active galactic nuclei Near infrared astronomy Galactic center |
| title_short |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| title_full |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| title_fullStr |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| title_full_unstemmed |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| title_sort |
Unprecedented Near-infrared Brightness and Variability of Sgr A∗ |
| dc.creator.none.fl_str_mv |
Do, T. Witzel, G. Gautam, A.K. Chen, Z. Ghez, A.M. Morris, M.R. Becklin, E.E. Ciurlo, A. Hosek, M. Martinez, G.D. Matthews, K. Sakai, S. Schödel, Rainer |
| author |
Do, T. |
| author_facet |
Do, T. Witzel, G. Gautam, A.K. Chen, Z. Ghez, A.M. Morris, M.R. Becklin, E.E. Ciurlo, A. Hosek, M. Martinez, G.D. Matthews, K. Sakai, S. Schödel, Rainer |
| author_role |
author |
| author2 |
Witzel, G. Gautam, A.K. Chen, Z. Ghez, A.M. Morris, M.R. Becklin, E.E. Ciurlo, A. Hosek, M. Martinez, G.D. Matthews, K. Sakai, S. Schödel, Rainer |
| author2_role |
author author author author author author author author author author author author |
| dc.contributor.none.fl_str_mv |
W. M. Keck Foundation Heising Simons Foundation Gordon and Betty Moore Foundation Lauren B. Leichtman and Arthur E. Levine Family Foundation European Research Council Ministerio de Ciencia, Innovación y Universidades (España) National Science Foundation (US) European Commission Ministerio de Economía y Competitividad (España) Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72] |
| dc.subject.none.fl_str_mv |
Supermassive black holes Low-luminosity active galactic nuclei Near infrared astronomy Galactic center |
| topic |
Supermassive black holes Low-luminosity active galactic nuclei Near infrared astronomy Galactic center |
| description |
The electromagnetic counterpart to the Galactic center supermassive black hole, Sgr A∗, has been observed in the near-infrared for over 20 yr and is known to be highly variable. We report new Keck Telescope observations showing that Sgr A∗ reached much brighter flux levels in 2019 than ever measured at near-infrared wavelengths. In the K′ band, Sgr A∗ reached flux levels of ∼6 mJy, twice the level of the previously observed peak flux from >13,000 measurements over 130 nights with the Very Large Telescope and Keck Telescopes. We also observe a factor of 75 change in flux over a 2 hr time span with no obvious color changes between 1.6 and 2.1 μm. The distribution of flux variations observed this year is also significantly different than the historical distribution. Using the most comprehensive statistical model published, the probability of a single night exhibiting peak flux levels observed this year, given historical Keck observations, is less than 0.3%. The probability of observing flux levels that are similar to all four nights of data in 2019 is less than 0.05%. This increase in brightness and variability may indicate a period of heightened activity from Sgr A∗ or a change in its accretion state. It may also indicate that the current model is not sufficient to model Sgr A∗ at high flux levels and should be updated. Potential physical origins of Sgr A∗'s unprecedented brightness may be from changes in the accretion flow as a result of the star S0-2's closest passage to the black hole in 2018, or from a delayed reaction to the approach of the dusty object G2 in 2014. Additional multi-wavelength observations will be necessary to both monitor Sgr A∗ for potential state changes and to constrain the physical processes responsible for its current variability.© 2019. The American Astronomical Society. All rights reserved.. |
| publishDate |
2019 |
| dc.date.none.fl_str_mv |
2019 2020 2020 2020 |
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info:eu-repo/semantics/article http://purl.org/coar/resource_type/c_6501 Postprint info:eu-repo/semantics/acceptedVersion |
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article |
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acceptedVersion |
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http://hdl.handle.net/10261/202063 |
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http://hdl.handle.net/10261/202063 |
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Inglés |
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Inglés |
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info:eu-repo/semantics/openAccess |
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openAccess |
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reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC instname:Consejo Superior de Investigaciones Científicas (CSIC) |
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Consejo Superior de Investigaciones Científicas (CSIC) |
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DIGITAL.CSIC. Repositorio Institucional del CSIC |
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1869408020235026432 |
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Unprecedented Near-infrared Brightness and Variability of Sgr A∗Do, T.Witzel, G.Gautam, A.K.Chen, Z.Ghez, A.M.Morris, M.R.Becklin, E.E.Ciurlo, A.Hosek, M.Martinez, G.D.Matthews, K.Sakai, S.Schödel, RainerSupermassive black holesLow-luminosity active galactic nucleiNear infrared astronomyGalactic centerThe electromagnetic counterpart to the Galactic center supermassive black hole, Sgr A∗, has been observed in the near-infrared for over 20 yr and is known to be highly variable. We report new Keck Telescope observations showing that Sgr A∗ reached much brighter flux levels in 2019 than ever measured at near-infrared wavelengths. In the K′ band, Sgr A∗ reached flux levels of ∼6 mJy, twice the level of the previously observed peak flux from >13,000 measurements over 130 nights with the Very Large Telescope and Keck Telescopes. We also observe a factor of 75 change in flux over a 2 hr time span with no obvious color changes between 1.6 and 2.1 μm. The distribution of flux variations observed this year is also significantly different than the historical distribution. Using the most comprehensive statistical model published, the probability of a single night exhibiting peak flux levels observed this year, given historical Keck observations, is less than 0.3%. The probability of observing flux levels that are similar to all four nights of data in 2019 is less than 0.05%. This increase in brightness and variability may indicate a period of heightened activity from Sgr A∗ or a change in its accretion state. It may also indicate that the current model is not sufficient to model Sgr A∗ at high flux levels and should be updated. Potential physical origins of Sgr A∗'s unprecedented brightness may be from changes in the accretion flow as a result of the star S0-2's closest passage to the black hole in 2018, or from a delayed reaction to the approach of the dusty object G2 in 2014. Additional multi-wavelength observations will be necessary to both monitor Sgr A∗ for potential state changes and to constrain the physical processes responsible for its current variability.© 2019. The American Astronomical Society. All rights reserved..We thank the anonymous referee for helpful comments. We thank the staff and astronomers at Keck Observatory especially Jim Lyke, Randy Campbell, Sherry Yeh, Greg Doppmann, Cynthia Wilburn, Terry Stickel, and Alan Hatakeyama. Support for this work was provided by NSF AAG grant AST-1412615, the W.M. Keck Foundation, the HeisingSimons Foundation, the Gordon and Betty Moore Foundation, the Levine-Leichtman Family Foundation, the Preston Family Graduate Fellowship (held by A.G.), and the UCLA Galactic Center Star Society. R. S. has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 614922. R.S. acknowledges financial support from the State Agency for Research of the Spanish MCIU through the >Center of Excellence Severo Ochoa> award for the Instituto de Astrofisica de Andalucia (SEV-2017-0709). This research was based on data products from the Galactic Center Orbits Initiative, which is hosted at UCLA and is a key science program of the Galactic Center Collaboration. The W.M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors wish to recognize that the summit of Maunakea has always held a very significant cultural role for the indigenous Hawaiian community. We are most fortunate to have the opportunity to observe from this mountain.W. M. Keck FoundationHeising Simons FoundationGordon and Betty Moore FoundationLauren B. Leichtman and Arthur E. Levine Family FoundationEuropean Research CouncilMinisterio de Ciencia, Innovación y Universidades (España)National Science Foundation (US)European CommissionMinisterio de Economía y Competitividad (España)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2020202020192020info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Postprintinfo:eu-repo/semantics/acceptedVersionhttp://hdl.handle.net/10261/202063reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE##PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/EC/H2020/614922info:eu-repo/grantAgreement/MINECO/Plan Estatal de Investigación Científica y Técnica y de Innovación 2013-2016/SEV-2017-0709http://dx.doi.org/10.3847/2041-8213/ab38c3Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/2020632026-05-22T06:33:51Z |
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