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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2604.10287 |
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| author | Albentosa-Ruiz, Ezequiel Washington, Jasmin E. Marchili, Nicola Martí-Vidal, Iván Goddi, Ciriaco Wielgus, Maciek Mus, Alejandro Ricarte, Angelo Marrone, Daniel P. Salas, León D. S. Iwata, Yuhei Carlos, Douglas F. Tetarenko, Alexandra J. Moriyama, Kotaro Dhruv, Vedant Akiyama, Kazunori Alberdi, Antxon Alef, Walter Algaba, Juan Carlos Anantua, Richard Asada, Keiichi Azulay, Rebecca Bach, Uwe Baczko, Anne-Kathrin Ball, David Baloković, Mislav Bandyopadhyay, Bidisha Barrett, John Bauböck, Michi Benson, Bradford A. Bintley, Dan Blackburn, Lindy Blundell, Raymond Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Bustamante, Sandra Carlstrom, John E. Chael, Andrew Chan, Chi-kwan Chang, Dominic O. Chatterjee, Koushik Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cheng, Xiaopeng Christian, Pierre Cho, Ilje Conroy, Nicholas S. Conway, John E. Crawford, Thomas M. Crew, Geoffrey B. Cruz-Osorio, Alejandro Cui, Yuzhu Curd, Brandon Dahale, Rohan Davelaar, Jordy De Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Dihingia, Indu K. Doeleman, Sheperd S. Dzib, Sergio A. Eatough, Ralph P. Emami, Razieh Falcke, Heino Farah, Joseph Fish, Vincent L. Fomalont, Edward Ford, H. Alyson Foschi, Marianna Fuentes, Antonio Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Geertsema, Gertie Georgiev, Boris Gold, Roman Gómez, José L. Gómez-Ruiz, Arturo I. Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Haggard, Daryl Hesper, Ronald Heumann, Dirk Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Impellizzeri, C. M. Violette Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Jiménez-Rosales, Alejandra Johnson, Michael D. Jones, Adam C. Jorstad, Svetlana Joshi, Abhishek V. Jung, Taehyun Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kino, Motoki Koay, Jun Yi Kocherlakota, Prashant Kofuji, Yutaro Koch, Patrick M. Koyama, Shoko Kramer, Carsten Kramer, Joana A. Kramer, Michael Krichbaum, Thomas P. Kuo, Cheng-Yu La Bella, Noemi Lee, Sang-Sung Levis, Aviad Li, Zhiyuan Lico, Rocco Lindahl, Greg Lindqvist, Michael Lisakov, Mikhail Liu, Jun Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin J. Lowitz, Amy E. Lu, Ru-Sen Mao, Jirong Markoff, Sera Marscher, Alan P. Matsushita, Satoki Matthews, Lynn D. Medeiros, Lia Menten, Karl M. Mizuno, Izumi Mizuno, Yosuke Montgomery, Joshua Moran, James M. Moscibrodzka, Monika Mulaudzi, Wanga Müller, Hendrik Müller, Cornelia Musoke, Gibwa Myserlis, Ioannis Nagai, Hiroshi Nagar, Neil M. Nair, Dhanya G. Nakamura, Masanori Narayanan, Gopal Natarajan, Iniyan Nathanail, Antonios Fuentes, Santiago Navarro Neilsen, Joey Ni, Chunchong Nowak, Michael A. Oh, Junghwan Okino, Hiroki Sánchez, Héctor Raúl Olivares Oyama, Tomoaki Özel, Feryal Palumbo, Daniel C. M. Paraschos, Georgios Filippos Park, Jongho Parsons, Harriet Patel, Nimesh Pen, Ue-Li Pesce, Dominic W. Piétu, Vincent PopStefanija, Aleksandar Porth, Oliver Prather, Ben Principe, Giacomo Psaltis, Dimitrios Pu, Hung-Yi Ramakrishnan, Venkatessh Rao, Ramprasad Rawlings, Mark G. Rezzolla, Luciano Ripperda, Bart Röder, Jan Roelofs, Freek Romero-Cañizales, Cristina Ros, Eduardo Roshanineshat, Arash Rottmann, Helge Roy, Alan L. Ruiz, Ignacio Ruszczyk, Chet Rygl, Kazi L. J. Sánchez, Salvador Sánchez-Argüelles, David Sánchez-Portal, Miguel Sasada, Mahito Satapathy, Kaushik Saurabh Savolainen, Tuomas Schloerb, F. Peter Schonfeld, Jonathan Schuster, Karl-Friedrich Shao, Lijing Shen, Zhiqiang Silpa, Sasikumar Small, Des Sohn, Bong Won SooHoo, Jason Souccar, Kamal Stanway, Joshua S. Sun, He Tazaki, Fumie Tiede, Paul Tilanus, Remo P. J. Titus, Michael Toma, Kenji Torne, Pablo Toscano, Teresa Traianou, Efthalia Trent, Tyler Trippe, Sascha Turk, Matthew van Bemmel, Ilse van Langevelde, Huib Jan van Rossum, Daniel R. Vos, Jesse Wagner, Jan Ward-Thompson, Derek Wardle, John Weintroub, Jonathan Wharton, Robert Wiik, Kaj Witzel, Gunther Wondrak, Michael F. Wong, George N. Wu, Qingwen Yadlapalli, Nitika Yamaguchi, Paul Yfantis, Aristomenis Yoon, Doosoo Young, André Younsi, Ziri Yu, Wei Yuan, Feng Yuan, Ye-Fei Zeng, Ai-Ling Zensus, J. Anton Zhang, Shuo Zhao, Guang-Yao Zhao, Shan-Shan |
| author_facet | Albentosa-Ruiz, Ezequiel Washington, Jasmin E. Marchili, Nicola Martí-Vidal, Iván Goddi, Ciriaco Wielgus, Maciek Mus, Alejandro Ricarte, Angelo Marrone, Daniel P. Salas, León D. S. Iwata, Yuhei Carlos, Douglas F. Tetarenko, Alexandra J. Moriyama, Kotaro Dhruv, Vedant Akiyama, Kazunori Alberdi, Antxon Alef, Walter Algaba, Juan Carlos Anantua, Richard Asada, Keiichi Azulay, Rebecca Bach, Uwe Baczko, Anne-Kathrin Ball, David Baloković, Mislav Bandyopadhyay, Bidisha Barrett, John Bauböck, Michi Benson, Bradford A. Bintley, Dan Blackburn, Lindy Blundell, Raymond Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Bustamante, Sandra Carlstrom, John E. Chael, Andrew Chan, Chi-kwan Chang, Dominic O. Chatterjee, Koushik Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cheng, Xiaopeng Christian, Pierre Cho, Ilje Conroy, Nicholas S. Conway, John E. Crawford, Thomas M. Crew, Geoffrey B. Cruz-Osorio, Alejandro Cui, Yuzhu Curd, Brandon Dahale, Rohan Davelaar, Jordy De Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Dihingia, Indu K. Doeleman, Sheperd S. Dzib, Sergio A. Eatough, Ralph P. Emami, Razieh Falcke, Heino Farah, Joseph Fish, Vincent L. Fomalont, Edward Ford, H. Alyson Foschi, Marianna Fuentes, Antonio Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Geertsema, Gertie Georgiev, Boris Gold, Roman Gómez, José L. Gómez-Ruiz, Arturo I. Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Haggard, Daryl Hesper, Ronald Heumann, Dirk Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Impellizzeri, C. M. Violette Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Jiménez-Rosales, Alejandra Johnson, Michael D. Jones, Adam C. Jorstad, Svetlana Joshi, Abhishek V. Jung, Taehyun Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kino, Motoki Koay, Jun Yi Kocherlakota, Prashant Kofuji, Yutaro Koch, Patrick M. Koyama, Shoko Kramer, Carsten Kramer, Joana A. Kramer, Michael Krichbaum, Thomas P. Kuo, Cheng-Yu La Bella, Noemi Lee, Sang-Sung Levis, Aviad Li, Zhiyuan Lico, Rocco Lindahl, Greg Lindqvist, Michael Lisakov, Mikhail Liu, Jun Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin J. Lowitz, Amy E. Lu, Ru-Sen Mao, Jirong Markoff, Sera Marscher, Alan P. Matsushita, Satoki Matthews, Lynn D. Medeiros, Lia Menten, Karl M. Mizuno, Izumi Mizuno, Yosuke Montgomery, Joshua Moran, James M. Moscibrodzka, Monika Mulaudzi, Wanga Müller, Hendrik Müller, Cornelia Musoke, Gibwa Myserlis, Ioannis Nagai, Hiroshi Nagar, Neil M. Nair, Dhanya G. Nakamura, Masanori Narayanan, Gopal Natarajan, Iniyan Nathanail, Antonios Fuentes, Santiago Navarro Neilsen, Joey Ni, Chunchong Nowak, Michael A. Oh, Junghwan Okino, Hiroki Sánchez, Héctor Raúl Olivares Oyama, Tomoaki Özel, Feryal Palumbo, Daniel C. M. Paraschos, Georgios Filippos Park, Jongho Parsons, Harriet Patel, Nimesh Pen, Ue-Li Pesce, Dominic W. Piétu, Vincent PopStefanija, Aleksandar Porth, Oliver Prather, Ben Principe, Giacomo Psaltis, Dimitrios Pu, Hung-Yi Ramakrishnan, Venkatessh Rao, Ramprasad Rawlings, Mark G. Rezzolla, Luciano Ripperda, Bart Röder, Jan Roelofs, Freek Romero-Cañizales, Cristina Ros, Eduardo Roshanineshat, Arash Rottmann, Helge Roy, Alan L. Ruiz, Ignacio Ruszczyk, Chet Rygl, Kazi L. J. Sánchez, Salvador Sánchez-Argüelles, David Sánchez-Portal, Miguel Sasada, Mahito Satapathy, Kaushik Saurabh Savolainen, Tuomas Schloerb, F. Peter Schonfeld, Jonathan Schuster, Karl-Friedrich Shao, Lijing Shen, Zhiqiang Silpa, Sasikumar Small, Des Sohn, Bong Won SooHoo, Jason Souccar, Kamal Stanway, Joshua S. Sun, He Tazaki, Fumie Tiede, Paul Tilanus, Remo P. J. Titus, Michael Toma, Kenji Torne, Pablo Toscano, Teresa Traianou, Efthalia Trent, Tyler Trippe, Sascha Turk, Matthew van Bemmel, Ilse van Langevelde, Huib Jan van Rossum, Daniel R. Vos, Jesse Wagner, Jan Ward-Thompson, Derek Wardle, John Weintroub, Jonathan Wharton, Robert Wiik, Kaj Witzel, Gunther Wondrak, Michael F. Wong, George N. Wu, Qingwen Yadlapalli, Nitika Yamaguchi, Paul Yfantis, Aristomenis Yoon, Doosoo Young, André Younsi, Ziri Yu, Wei Yuan, Feng Yuan, Ye-Fei Zeng, Ai-Ling Zensus, J. Anton Zhang, Shuo Zhao, Guang-Yao Zhao, Shan-Shan |
| contents | Sagittarius A* (Srg A*), the supermassive black hole at the center of the Milky Way, provides a unique laboratory to study accretion dynamics and plasma processes near the event horizon. We investigated the variability and polarization properties of Srg A* using ALMA observations during the 2018 Event Horizon Telescope campaign. We analyzed high-cadence full-polarization light curves from ALMA at millimeter wavelengths, performed time-series analysis, and investigated the temporal behavior during an X-ray flare observed by Chandra on 2018 April 24. The variability characteristics are compared with expectations from standard accretion flow models. We find low variability in total intensity ($σ/μ< 10\%$), but significantly higher variability in linear and circular polarization (~ 30% and ~ 50%, respectively). A time-series analysis reveals red-noise variability, with power spectral densities between -2 and -3 across all Stokes parameters. Polarized intensity shows stable intra-day timescales, while total intensity exhibits more variable timescales, suggesting distinct emission regions, with polarization likely arising from a coherent structure. On April 24, a statistically significant inter-band delay in polarized intensity coincides with a near-simultaneous X-ray and millimeter peak that deviates from the typical delayed flare scenario. This event also features enhanced millimeter variability and coherent polarization loop evolution. The observed simultaneity challenges standard models of transient synchrotron emission with cooling delays, favoring instead a scenario of continuous energy injection in an optically thin region. Our results offer new constraints on the physical mechanisms driving variability in Srg A*, and provide key observational input for refining theoretical models of accretion and plasma behavior in the vicinity of supermassive black holes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_10287 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaign Albentosa-Ruiz, Ezequiel Washington, Jasmin E. Marchili, Nicola Martí-Vidal, Iván Goddi, Ciriaco Wielgus, Maciek Mus, Alejandro Ricarte, Angelo Marrone, Daniel P. Salas, León D. S. Iwata, Yuhei Carlos, Douglas F. Tetarenko, Alexandra J. Moriyama, Kotaro Dhruv, Vedant Akiyama, Kazunori Alberdi, Antxon Alef, Walter Algaba, Juan Carlos Anantua, Richard Asada, Keiichi Azulay, Rebecca Bach, Uwe Baczko, Anne-Kathrin Ball, David Baloković, Mislav Bandyopadhyay, Bidisha Barrett, John Bauböck, Michi Benson, Bradford A. Bintley, Dan Blackburn, Lindy Blundell, Raymond Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Bustamante, Sandra Carlstrom, John E. Chael, Andrew Chan, Chi-kwan Chang, Dominic O. Chatterjee, Koushik Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cheng, Xiaopeng Christian, Pierre Cho, Ilje Conroy, Nicholas S. Conway, John E. Crawford, Thomas M. Crew, Geoffrey B. Cruz-Osorio, Alejandro Cui, Yuzhu Curd, Brandon Dahale, Rohan Davelaar, Jordy De Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Dihingia, Indu K. Doeleman, Sheperd S. Dzib, Sergio A. Eatough, Ralph P. Emami, Razieh Falcke, Heino Farah, Joseph Fish, Vincent L. Fomalont, Edward Ford, H. Alyson Foschi, Marianna Fuentes, Antonio Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Geertsema, Gertie Georgiev, Boris Gold, Roman Gómez, José L. Gómez-Ruiz, Arturo I. Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Haggard, Daryl Hesper, Ronald Heumann, Dirk Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Impellizzeri, C. M. Violette Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Jiménez-Rosales, Alejandra Johnson, Michael D. Jones, Adam C. Jorstad, Svetlana Joshi, Abhishek V. Jung, Taehyun Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kino, Motoki Koay, Jun Yi Kocherlakota, Prashant Kofuji, Yutaro Koch, Patrick M. Koyama, Shoko Kramer, Carsten Kramer, Joana A. Kramer, Michael Krichbaum, Thomas P. Kuo, Cheng-Yu La Bella, Noemi Lee, Sang-Sung Levis, Aviad Li, Zhiyuan Lico, Rocco Lindahl, Greg Lindqvist, Michael Lisakov, Mikhail Liu, Jun Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin J. Lowitz, Amy E. Lu, Ru-Sen Mao, Jirong Markoff, Sera Marscher, Alan P. Matsushita, Satoki Matthews, Lynn D. Medeiros, Lia Menten, Karl M. Mizuno, Izumi Mizuno, Yosuke Montgomery, Joshua Moran, James M. Moscibrodzka, Monika Mulaudzi, Wanga Müller, Hendrik Müller, Cornelia Musoke, Gibwa Myserlis, Ioannis Nagai, Hiroshi Nagar, Neil M. Nair, Dhanya G. Nakamura, Masanori Narayanan, Gopal Natarajan, Iniyan Nathanail, Antonios Fuentes, Santiago Navarro Neilsen, Joey Ni, Chunchong Nowak, Michael A. Oh, Junghwan Okino, Hiroki Sánchez, Héctor Raúl Olivares Oyama, Tomoaki Özel, Feryal Palumbo, Daniel C. M. Paraschos, Georgios Filippos Park, Jongho Parsons, Harriet Patel, Nimesh Pen, Ue-Li Pesce, Dominic W. Piétu, Vincent PopStefanija, Aleksandar Porth, Oliver Prather, Ben Principe, Giacomo Psaltis, Dimitrios Pu, Hung-Yi Ramakrishnan, Venkatessh Rao, Ramprasad Rawlings, Mark G. Rezzolla, Luciano Ripperda, Bart Röder, Jan Roelofs, Freek Romero-Cañizales, Cristina Ros, Eduardo Roshanineshat, Arash Rottmann, Helge Roy, Alan L. Ruiz, Ignacio Ruszczyk, Chet Rygl, Kazi L. J. Sánchez, Salvador Sánchez-Argüelles, David Sánchez-Portal, Miguel Sasada, Mahito Satapathy, Kaushik Saurabh Savolainen, Tuomas Schloerb, F. Peter Schonfeld, Jonathan Schuster, Karl-Friedrich Shao, Lijing Shen, Zhiqiang Silpa, Sasikumar Small, Des Sohn, Bong Won SooHoo, Jason Souccar, Kamal Stanway, Joshua S. Sun, He Tazaki, Fumie Tiede, Paul Tilanus, Remo P. J. Titus, Michael Toma, Kenji Torne, Pablo Toscano, Teresa Traianou, Efthalia Trent, Tyler Trippe, Sascha Turk, Matthew van Bemmel, Ilse van Langevelde, Huib Jan van Rossum, Daniel R. Vos, Jesse Wagner, Jan Ward-Thompson, Derek Wardle, John Weintroub, Jonathan Wharton, Robert Wiik, Kaj Witzel, Gunther Wondrak, Michael F. Wong, George N. Wu, Qingwen Yadlapalli, Nitika Yamaguchi, Paul Yfantis, Aristomenis Yoon, Doosoo Young, André Younsi, Ziri Yu, Wei Yuan, Feng Yuan, Ye-Fei Zeng, Ai-Ling Zensus, J. Anton Zhang, Shuo Zhao, Guang-Yao Zhao, Shan-Shan Astrophysics of Galaxies High Energy Astrophysical Phenomena Sagittarius A* (Srg A*), the supermassive black hole at the center of the Milky Way, provides a unique laboratory to study accretion dynamics and plasma processes near the event horizon. We investigated the variability and polarization properties of Srg A* using ALMA observations during the 2018 Event Horizon Telescope campaign. We analyzed high-cadence full-polarization light curves from ALMA at millimeter wavelengths, performed time-series analysis, and investigated the temporal behavior during an X-ray flare observed by Chandra on 2018 April 24. The variability characteristics are compared with expectations from standard accretion flow models. We find low variability in total intensity ($σ/μ< 10\%$), but significantly higher variability in linear and circular polarization (~ 30% and ~ 50%, respectively). A time-series analysis reveals red-noise variability, with power spectral densities between -2 and -3 across all Stokes parameters. Polarized intensity shows stable intra-day timescales, while total intensity exhibits more variable timescales, suggesting distinct emission regions, with polarization likely arising from a coherent structure. On April 24, a statistically significant inter-band delay in polarized intensity coincides with a near-simultaneous X-ray and millimeter peak that deviates from the typical delayed flare scenario. This event also features enhanced millimeter variability and coherent polarization loop evolution. The observed simultaneity challenges standard models of transient synchrotron emission with cooling delays, favoring instead a scenario of continuous energy injection in an optically thin region. Our results offer new constraints on the physical mechanisms driving variability in Srg A*, and provide key observational input for refining theoretical models of accretion and plasma behavior in the vicinity of supermassive black holes. |
| title | Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaign |
| topic | Astrophysics of Galaxies High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2604.10287 |