Article
Astronomy & Astrophysics
Masaru Siino
Summary: The role of the wandering null geodesic in a black hole spacetime is examined, revealing that it commonly exists and explains typical phenomena observed in the optical observation of event horizons. Additionally, a new concept called the black room is explored, establishing a closer connection between the wandering null geodesic and the black hole shadow.
Article
Astronomy & Astrophysics
Andrew Chael, Sara Issaoun, Dominic W. Pesce, Michael D. Johnson, Angelo Ricarte, Christian M. Fromm, Yosuke Mizuno
Summary: The Event Horizon Telescope has produced high-resolution images of plasma flow around supermassive black holes in Sgr A* and M87* using advanced imaging technology. The next-generation Event Horizon Telescope will significantly improve observation data with multiple frequency bands. Simultaneous reconstruction of interferometric images at multiple frequencies along with their spectral index maps produces higher-quality and more scientifically useful results than independent image reconstructions at each frequency.
ASTROPHYSICAL JOURNAL
(2023)
Article
Multidisciplinary Sciences
J. A. Campos, M. A. Anacleto, F. A. Brito, E. Passos
Summary: This paper investigates the quasinormal modes for a scalar field around a noncommutative Schwarzschild black hole, and verifies the effect of noncommutativity on quasinormal frequencies using two widely used methods. It is found that the shadow radius decreases as the noncommutative parameter increases, and the shadow radius is nonzero even at the zero mass limit for finite noncommutative parameter.
SCIENTIFIC REPORTS
(2022)
Article
Astronomy & Astrophysics
D. Marin Pina, M. Orselli, D. Pica
Summary: In this study, we analyze the formation and evolution of the event horizon of a charged black hole binary merger. The presence of charge is found to affect the properties of the merger and can be used to investigate various theories of modified gravity and dark matter candidates. Additionally, the study offers insights into astrophysical phenomena involving black holes, such as degeneracies in gravitational wave parameter determination.
Article
Astronomy & Astrophysics
Chris L. Carilli, Nithyanandan Thyagarajan
Summary: This study reanalyzes the observations of the Event Horizon Telescope of M87 and applies traditional techniques to the data. The best starting models for image reconstruction are found to be an annulus or disk, producing images with low noise and minimal artifacts. The source appears as a ring or edge-brightened disk, with higher brightness in the southern half, in line with previous findings.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Nuclear
Zhaoyi Xu, Meirong Tang
Summary: In this study, we investigate the influence of a quantum deformed black hole on the black hole shadow in two-dimensional Dilaton gravity. The shape of the shadow boundary is found to be determined by the black hole spin, quantum correction parameter, and black hole type parameter. Different quantum correction parameters lead to different degrees of distortion in the black hole shadow, and the existence of different quantum deformed black holes significantly alters the size and shape of the black hole shadow. These findings have important implications for understanding the quantum effects of black holes.
Article
Astronomy & Astrophysics
Rajibul Shaikh
Summary: The Event Horizon Telescope (EHT) has observed the image and shadow of Sagittarius A* (Sgr A*), which is believed to be a supermassive black hole. The observed image is consistent with the expected appearance of a Kerr black hole, but there are other non-Kerr objects that could also produce similar shadows. In this study, two black hole mimickers, including a rotating generalization of a static black-bounce space-time and a static axially-symmetric solution of the vacuum Einstein's equations, were considered and their shadows were compared with the observed shadow of Sgr A* to constrain their parameters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ru Ling, Hong Guo, Hang Liu, Xiao-Mei Kuang, Bin Wang
Summary: This paper analyzes the horizon structure of an acoustic charged black hole in curved spacetime, studying its acoustic shadow, QNM frequencies, and analog Hawking radiation. The study finds that the acoustic charged black hole is stable under perturbation and its energy emission rate is suppressed by angular momentum and charge.
Article
Astronomy & Astrophysics
Song Li, Temurbek Mirzaev, Ahmadjon A. Abdujabbarov, Daniele Malafarina, Bobomurat Ahmedov, Wen-Biao Han
Summary: The article investigates the optical properties of a black hole mimicker, compares the shape of its shadow with that of a Kerr black hole, and attempts to obtain constraints through a model. Based on the observation of the shadow's boundary, it concludes that the 6-Kerr solution cannot be excluded.
Article
Astronomy & Astrophysics
Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Svetlana Jorstad, Abhishek Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Tod R. Lauer, Daeyoung Lee, Sang-Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Ru-Sen Lu, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Daniel Michalik, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Monika Moscibrodzka, Cornelia Muller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Junghwan Oh, Hiroki Okino, Hector Olivares, Gisela N. Ortiz-Leon, Tomoaki Oyama, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Felix M. Potzl, Ben Prather, Jorge A. Preciado-Lopez, Dimitrios Psaltis, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Angelo Ricarte, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sanchez, David Sanchez-Arguelles, Miguel Sanchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, Kaj Wiik, Gunther Witzel, Michael F. Wondrak, George N. Wong, Qingwen Wu, Paul Yamaguchi, Doosoo Yoon, Andre Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, Shan-Shan Zhao
Summary: This study presents new constraints on potential deviations from the Kerr metric based on observations of Sagittarius A* (Sgr A*) using the 2017 Event Horizon Telescope. The authors calibrate the relationship between the black hole shadow and the observed size of ring-like images using both Kerr and non-Kerr simulations. They conclude that the observed image size is within similar to 10% of the Kerr predictions and use these bounds to constrain alternative metrics and charges of spacetimes. The study also explores the possibility of Sgr A* being a compact object with a thermal or reflective surface and compares the results to other gravitational tests.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Svetlana Jorstad, Abhishek Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Tod R. Lauer, Daeyoung Lee, Sang-Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Ru-Sen Lu, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Daniel Michalik, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Monika Moscibrodzka, Cornelia Muller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Junghwan Oh, Hiroki Okino, Hector Olivares, Gisela N. Ortiz-Leon, Tomoaki Oyama, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Felix M. Potzl, Ben Prather, Jorge A. Preciado-Lopez, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Angelo Ricarte, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sanchez, David Sanchez-Arguelles, Miguel Sanchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, He Sun, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, Kaj Wiik, Gunther Witzel, Michael F. Wondrak, George N. Wong, Qingwen Wu, Paul Yamaguchi, Doosoo Yoon, Andre Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, Shan-Shan Zhao, Dominic O. Chang
Summary: This paper quantifies the temporal variability and image morphology of the horizon-scale emission from Sgr A* observed by the EHT in 2017. It finds that the data exhibit significant variability exceeding uncertainties and scattering effects. Geometric ring models provide better fits to the data, and the diameter and thickness of the ring are determined through modeling and image-domain analysis techniques.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Farruh Atamurotov, Kimet Jusufi, Mubasher Jamil, Ahmadjon Abdujabbarov, Mustapha Azreg-Ainou
Summary: This paper investigates the influence of axion-plasmon on the optical properties of Schwarzschild black hole. It is found that the size of the black hole shadow decreases with increasing axion-plasmon coupling, indicating changes in gravitational deflection angle and other properties.
Article
Astronomy & Astrophysics
Adrian Ka-Wai Chung, Joseph Gais, Mark Ho-Yeuk Cheung, Tjonnie G. F. Li
Summary: In this study, the shifts of gravitational quasinormal-mode frequencies of a rotating black hole due to the presence of a surrounding bosonic cloud were calculated. A mock analysis was performed on simulated Laser Interferometer Space Antenna observational data containing injected ringdown signals from supermassive black holes. The findings suggest that the existence of cloud-forming ultralight bosons can be determined with less than an hour of observational data.
Article
Physics, Particles & Fields
Qing-Hua Zhu, Yu-Xuan Han, Qing-Guo Huang
Summary: In this paper, the shadow of the supertranslated black hole is investigated using supertranslated 4-velocities and the trajectories of light rays. It is found that although the photon sphere gets distorted and the position of the shadow is shifted by the supertranslation vector, the size and shape of the shadow remain the same as those of a bald black hole. The shift in the position of the shadow is a result of the choice of coordinate and does not have any distinguishable effects on the supertranslated black hole.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Balokovic, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Jason Dexter, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Svetlana Jorstad, Abhishek Joshi, Taehyun Jung, Mansour Karami, Ramesh Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Tod R. Lauer, Daeyoung Lee, Sang-Sung Lee, Po Kin Leung, Aviad Levis, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Ru-Sen Lu, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Daniel Michalik, Izumi Mizuno, Yosuke Mizuno, James M. Moran, Kotaro Moriyama, Monika Moscibrodzka, Cornelia Mueller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Andrew Nadolski, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Ramesh Narayan, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Roberto Neri, Chunchong Ni, Aristeidis Noutsos, Michael A. Nowak, Junghwan Oh, Hiroki Okino, Hector Olivares, Gisela N. Ortiz-Leon, Tomoaki Oyama, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Richard Plambeck, Aleksandar PopStefanija, Oliver Porth, Felix M. Potzl, Ben Prather, Jorge A. Preciado-Lopez, Dimitrios Psaltis, Hung-Yi Pu, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Alexander W. Raymond, Luciano Rezzolla, Angelo Ricarte, Bart Ripperda, Freek Roelofs, Alan Rogers, Eduardo Ros, Cristina Romero-Canizales, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Salvador Sanchez, David Sanchez-Arguelles, Miguel Sanchez-Portal, Mahito Sasada, Kaushik Satapathy, Tuomas Savolainen, F. Peter Schloerb, Jonathan Schonfeld, Karl-Friedrich Schuster, Lijing Shao, Zhiqiang Shen, Des Small, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Fumie Tazaki, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Pablo Torne, Efthalia Traianou, Tyler Trent, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Derek Ward-Thompson, John Wardle, Jonathan Weintroub, Norbert Wex, Robert Wharton, Maciek Wielgus, Kaj Wiik, Gunther Witzel, Michael F. Wondrak, George N. Wong, Qingwen Wu, Paul Yamaguchi, Doosoo Yoon, Andre Young, Ken Young, Ziri Younsi, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, Shan-Shan Zhao
Summary: This article presents the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in April 2017. Different imaging methods and scattering effect corrections were used to reconstruct the static images of Sgr A*. The analysis shows that the Sgr A* image is dominated by a bright ring of emission with a diameter of about 50 microarcseconds, consistent with the expected shadow of a 4 x 10^6 solar mass black hole in the Galactic center at a distance of 8 kiloparsecs.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Nicolas Sanchis-Gual, Carlos Herdeiro, Eugen Radu
Summary: This study investigates the time evolution of spherical, excited boson star models and demonstrates that large self-interactions can stabilize the excited states. The formation of these states is found to occur through the gravitational cooling mechanism, starting from dilute initial data.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Carlos A. R. Herdeiro, Eugen Radu
Summary: According to generic arguments, solutions of the Klein-Gordon and Proca equations can be treated as classical if their typical action satisfies certain conditions, which is reasonable for describing the properties of typical bosonic stars.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Physics, Multidisciplinary
Pedro V. P. Cunha, Carlos Herdeiro, Eugen Radu, Nicolas Sanchis-Gual
Summary: Ultracompact objects with light rings but without an event horizon can mimic black holes in their strong gravity phenomenology. Through numerical simulations and the introduction of a novel technique, we confirm the instability triggered by the light rings and identify two possible outcomes: migration to nonultracompact configurations or collapse to black holes.
PHYSICAL REVIEW LETTERS
(2023)
Article
Astronomy & Astrophysics
Burkhard Kleihaus, Jutta Kunz, Eugen Radu
Summary: We investigated various classes of asymptotically flat, rotating black objects in d=5 Einstein-Gauss-Bonnet (EGB) theory. These include black holes with two equal-magnitude angular momenta, and we also studied extremal configurations. Our numerical evidence suggests the existence of EGB generalizations of Myers-Perry black holes with a single plane of rotation and Emparan-Reall balanced black rings. All solutions approach the Minkowski background asympotically and are free of singularities outside or on the horizon. The numerical results indicate that rotating configurations exist up to a maximal value of the GB coupling constant for any solution mass and horizon topology, while solutions with a spherical horizon topology still satisfy the Einstein gravity bound on angular momentum.
Article
Astronomy & Astrophysics
Alejandro Cruz-Osorio, Lucian Rezzolla, Fabio D. Lora-Clavijo, Jose Antonio Font, Carlos Herdeiro, Eugen Radu
Summary: We present a numerical study of relativistic Bondi-Hoyle-Lyttleton accretion onto a black hole with synchronized hair. The steady-state solutions obtained provide insights into the formation of black holes in the presence of ultralight scalar fields and the possible association between the shock-cone and quasi-periodic oscillations in X-ray light curves.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Zeus S. Moreira, Haroldo C. D. Lima Jr, Luis C. B. Crispino, Carlos A. R. Herdeiro
Summary: In this study, we analyze the quasinormal modes (QNMs) of a Schwarzschild black hole with corrections motivated by Loop Quantum Gravity (LQG). The black hole exhibits a global structure of a black bounce, and the QNM frequency orbits in the complex plane are self-intersecting spiraling curves. The overall damping decreases with increasing LQG parameter, and the spectrum of the quantum corrected black hole shows an oscillatory pattern with possible QNMs having vanishing real part.
Article
Astronomy & Astrophysics
Marco Brito, Carlos Herdeiro, Eugen Radu, Nicolas Sanchis-Gual, Miguel Zilhao
Summary: We studied the time evolution of excited-scalar boson stars in general relativity coupled to a complex massive scalar field with quartic self-interactions. The stars with up to 10 radial nodes can be made dynamically stable for sufficiently large values of the self-interactions coupling constant lambda. The compactness of these solutions is insensitive to the number of radial nodes for large lambda and fixed frequency.
Article
Astronomy & Astrophysics
Carlos A. R. Herdeiro, Eugen Radu
Summary: We show that Einstein-scalar theories allow balanced static, neutral, asymptotically flat, double-black hole solutions with appropriate self-interactions. The solutions are scalar hairy versions of the double-Schwarzschild (or Bach-Weyl) solution, but regular on and outside the two horizons. The balancing repulsive force is provided by the scalar field.
Article
Astronomy & Astrophysics
Pedro Ildefonso, Miguel Zilhao, Carlos Herdeiro, Eugen Radu, Nuno M. Santos
Summary: In this study, dipolar self-interacting scalar boson stars are constructed and dynamically evolved in a model with sextic (or quartic) self-interactions. The domain of existence of dipolar Q-stars has a similar structure to that of fundamental monopolar stars in the same model. The evolutions show that the dipolar Q-stars exhibit similar dynamical properties: 1) in the Newtonian and relativistic branches, they are dynamically robust over longer time scales compared to dipolar stars without self-interactions; 2) in the middle branch, they migrate to either the Newtonian or the relativistic branch; 3) beyond the relativistic branch, they decay to black holes. Overall, these results strengthen the observation that self-interactions can mitigate dynamical instabilities of scalar boson star models.
Article
Astronomy & Astrophysics
Nuno M. Santos, Carlos A. R. Herdeiro, Eugen Radu
Summary: This study finds that in some models, scalarized BHs bifurcating from Reissner-Nordstrom and spinning BHs with synchronized hair bifurcating from Kerr do not have local thermodynamic stability.
Article
Physics, Particles & Fields
Jose Luis Blazquez-Salcedo, Christian Knoll, E. Radu
Summary: This paper presents a discussion of the traversable wormholes in Einstein-Dirac-Maxwell theory, with a detailed description of the ansatz and junction condition, as well as an investigation of the domain of existence of the solutions. Possible issues and limitations of the approach are also discussed.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Jorge F. M. Delgado, Carlos A. R. Herdeiro, Eugen Radu
Summary: This study focuses on the structure of timelike circular orbits (TCOs) near equatorial light rings (LRs) for stationary, axisymmetric, asymptotically flat, ultracompact objects with Z(2) north-south symmetry. The results show that the radial stability of LRs exclusively determines the structure of TCOs, suggesting potential applications for horizonless ultracompact objects and black holes.