Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification
We study the kinematics of the M87 jet using the first-year data of the KVN and VERA Array (KaVA) large program, which has densely monitored the jet at 22 and 43 GHz since 2016. We find that the apparent jet speeds generally increase from ≈0.3c at ≈0.5 mas from the jet base to ≈2.7c at ≈20 mas, indi...
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| Format: | Article |
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IOP Publishing
2019
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| author | Park, Jongho Hada, Kazuhiro Kino, Motoki Nakamura, Masanori Hodgson, Jeffrey Ro, Hyunwook Cui, Yuzhu Asada, Keiichi Algaba, Juan Carlos Sawada-Satoh, Satoko Lee, Sang-Sung Cho, Ilje Shen, Zhiqiang Jiang, Wu Trippe, Sascha Niinuma, Kotaro Sohn, Bong Won Jung, Taehyun Zhao, Guang-Yao Wajima, Kiyoaki Tazaki, Fumie Honma, Mareki An, Tao Akiyama, Kazunori Byun, Do-Young Kim, Jongsoo Zhang, Yingkang Cheng, Xiaopeng Kobayashi, Hideyuki Shibata, Katsunori M. Lee, Jee Won Roh, Duk-Gyoo Oh, Se-Jin Yeom, Jae-Hwan Jung, Dong-Kyu Oh, Chungsik Kim, Hyo-Ryoung Hwang, Ju-Yeon Hagiwara, Yoshiaki |
| author_facet | Park, Jongho Hada, Kazuhiro Kino, Motoki Nakamura, Masanori Hodgson, Jeffrey Ro, Hyunwook Cui, Yuzhu Asada, Keiichi Algaba, Juan Carlos Sawada-Satoh, Satoko Lee, Sang-Sung Cho, Ilje Shen, Zhiqiang Jiang, Wu Trippe, Sascha Niinuma, Kotaro Sohn, Bong Won Jung, Taehyun Zhao, Guang-Yao Wajima, Kiyoaki Tazaki, Fumie Honma, Mareki An, Tao Akiyama, Kazunori Byun, Do-Young Kim, Jongsoo Zhang, Yingkang Cheng, Xiaopeng Kobayashi, Hideyuki Shibata, Katsunori M. Lee, Jee Won Roh, Duk-Gyoo Oh, Se-Jin Yeom, Jae-Hwan Jung, Dong-Kyu Oh, Chungsik Kim, Hyo-Ryoung Hwang, Ju-Yeon Hagiwara, Yoshiaki |
| author_sort | Park, Jongho |
| collection | UM |
| description | We study the kinematics of the M87 jet using the first-year data of the KVN and VERA Array (KaVA) large program, which has densely monitored the jet at 22 and 43 GHz since 2016. We find that the apparent jet speeds generally increase from ≈0.3c at ≈0.5 mas from the jet base to ≈2.7c at ≈20 mas, indicating that the jet is accelerated from subluminal to superluminal speeds on these scales. We perform a complementary jet kinematic analysis by using archival Very Long Baseline Array monitoring data observed in 2005-2009 at 1.7 GHz and find that the jet is moving at relativistic speeds up to ≈5.8c at distances of 200-410 mas. We combine the two kinematic results and find that the jet is gradually accelerated over a broad distance range that coincides with the jet collimation zone, implying that conversion of Poynting flux to kinetic energy flux takes place. If the jet emission consists of a single streamline, the observed trend of jet acceleration (Γ ∝ z 0.16±0.01) is relatively slow compared to models of a highly magnetized jet. This indicates that Poynting flux conversion through the differential collimation of poloidal magnetic fields may be less efficient than expected. However, we find a nonnegligible dispersion in the observed speeds for a given jet distance, making it difficult to describe the jet velocity field with a single power-law acceleration function. We discuss the possibility that the jet emission consists of multiple streamlines following different acceleration profiles, resulting in jet velocity stratification. © 2019. The American Astronomical Society. All rights reserved. |
| first_indexed | 2024-03-06T06:00:48Z |
| format | Article |
| id | um.eprints-23763 |
| institution | Universiti Malaya |
| last_indexed | 2024-03-06T06:00:48Z |
| publishDate | 2019 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | um.eprints-237632020-02-12T03:56:14Z http://eprints.um.edu.my/23763/ Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification Park, Jongho Hada, Kazuhiro Kino, Motoki Nakamura, Masanori Hodgson, Jeffrey Ro, Hyunwook Cui, Yuzhu Asada, Keiichi Algaba, Juan Carlos Sawada-Satoh, Satoko Lee, Sang-Sung Cho, Ilje Shen, Zhiqiang Jiang, Wu Trippe, Sascha Niinuma, Kotaro Sohn, Bong Won Jung, Taehyun Zhao, Guang-Yao Wajima, Kiyoaki Tazaki, Fumie Honma, Mareki An, Tao Akiyama, Kazunori Byun, Do-Young Kim, Jongsoo Zhang, Yingkang Cheng, Xiaopeng Kobayashi, Hideyuki Shibata, Katsunori M. Lee, Jee Won Roh, Duk-Gyoo Oh, Se-Jin Yeom, Jae-Hwan Jung, Dong-Kyu Oh, Chungsik Kim, Hyo-Ryoung Hwang, Ju-Yeon Hagiwara, Yoshiaki Q Science (General) QB Astronomy QC Physics We study the kinematics of the M87 jet using the first-year data of the KVN and VERA Array (KaVA) large program, which has densely monitored the jet at 22 and 43 GHz since 2016. We find that the apparent jet speeds generally increase from ≈0.3c at ≈0.5 mas from the jet base to ≈2.7c at ≈20 mas, indicating that the jet is accelerated from subluminal to superluminal speeds on these scales. We perform a complementary jet kinematic analysis by using archival Very Long Baseline Array monitoring data observed in 2005-2009 at 1.7 GHz and find that the jet is moving at relativistic speeds up to ≈5.8c at distances of 200-410 mas. We combine the two kinematic results and find that the jet is gradually accelerated over a broad distance range that coincides with the jet collimation zone, implying that conversion of Poynting flux to kinetic energy flux takes place. If the jet emission consists of a single streamline, the observed trend of jet acceleration (Γ ∝ z 0.16±0.01) is relatively slow compared to models of a highly magnetized jet. This indicates that Poynting flux conversion through the differential collimation of poloidal magnetic fields may be less efficient than expected. However, we find a nonnegligible dispersion in the observed speeds for a given jet distance, making it difficult to describe the jet velocity field with a single power-law acceleration function. We discuss the possibility that the jet emission consists of multiple streamlines following different acceleration profiles, resulting in jet velocity stratification. © 2019. The American Astronomical Society. All rights reserved. IOP Publishing 2019 Article PeerReviewed Park, Jongho and Hada, Kazuhiro and Kino, Motoki and Nakamura, Masanori and Hodgson, Jeffrey and Ro, Hyunwook and Cui, Yuzhu and Asada, Keiichi and Algaba, Juan Carlos and Sawada-Satoh, Satoko and Lee, Sang-Sung and Cho, Ilje and Shen, Zhiqiang and Jiang, Wu and Trippe, Sascha and Niinuma, Kotaro and Sohn, Bong Won and Jung, Taehyun and Zhao, Guang-Yao and Wajima, Kiyoaki and Tazaki, Fumie and Honma, Mareki and An, Tao and Akiyama, Kazunori and Byun, Do-Young and Kim, Jongsoo and Zhang, Yingkang and Cheng, Xiaopeng and Kobayashi, Hideyuki and Shibata, Katsunori M. and Lee, Jee Won and Roh, Duk-Gyoo and Oh, Se-Jin and Yeom, Jae-Hwan and Jung, Dong-Kyu and Oh, Chungsik and Kim, Hyo-Ryoung and Hwang, Ju-Yeon and Hagiwara, Yoshiaki (2019) Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification. The Astrophysical Journal, 887 (2). p. 147. ISSN 1538-4357, DOI https://doi.org/10.3847/1538-4357/ab5584 <https://doi.org/10.3847/1538-4357/ab5584>. https://doi.org/10.3847/1538-4357/ab5584 doi:10.3847/1538-4357/ab5584 |
| spellingShingle | Q Science (General) QB Astronomy QC Physics Park, Jongho Hada, Kazuhiro Kino, Motoki Nakamura, Masanori Hodgson, Jeffrey Ro, Hyunwook Cui, Yuzhu Asada, Keiichi Algaba, Juan Carlos Sawada-Satoh, Satoko Lee, Sang-Sung Cho, Ilje Shen, Zhiqiang Jiang, Wu Trippe, Sascha Niinuma, Kotaro Sohn, Bong Won Jung, Taehyun Zhao, Guang-Yao Wajima, Kiyoaki Tazaki, Fumie Honma, Mareki An, Tao Akiyama, Kazunori Byun, Do-Young Kim, Jongsoo Zhang, Yingkang Cheng, Xiaopeng Kobayashi, Hideyuki Shibata, Katsunori M. Lee, Jee Won Roh, Duk-Gyoo Oh, Se-Jin Yeom, Jae-Hwan Jung, Dong-Kyu Oh, Chungsik Kim, Hyo-Ryoung Hwang, Ju-Yeon Hagiwara, Yoshiaki Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title | Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title_full | Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title_fullStr | Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title_full_unstemmed | Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title_short | Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification |
| title_sort | kinematics of the m87 jet in the collimation zone gradual acceleration and velocity stratification |
| topic | Q Science (General) QB Astronomy QC Physics |
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