Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification
Park, Jongho1,2; Hada, Kazuhiro3,4; Kino, Motoki5,6; Nakamura, Masanori1; Hodgson, Jeffrey7; Ro, Hyunwook8; Cui, Yuzhu; Asada, Keiichi; Algaba, Juan-Carlos9; Sawada-Satoh, Satoko10; Lee, Sang-Sung7,11; Cho, Ilje7,11; Shen, Zhiqiang12,13; Jiang, Wu12,13; Trippe, Sascha2; Niinuma, Kotaro; Sohn, Bong Won7,11; Jung, Taehyun7,11; Zhao, Guang-Yao7; Wajima, Kiyoaki7; Tazaki, Fumie; Honma, Mareki3; An, Tao13; Akiyama, Kazunori14; Byun, Do-Young; Kim, Jongsoo7; Zhang, Yingkang12,15; Cheng, Xiaopeng12,15; Kobayashi, Hideyuki3; Shibata, Katsunori M.3; Lee, Jee Won7,16; Roh, Duk-Gyoo; Oh, Se-Jin; Yeom, Jae-Hwan7; Jung, Dong-Kyu7; Oh, Chungsik7; Kim, Hyo-Ryoung7; Hwang, Ju-Yeon7; Hagiwara, Yoshiaki17
Corresponding AuthorPark, Jongho(
AbstractWe 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 approximate to 0.3c at approximate to 0.5 mas from the jet base to approximate to 2.7c at approximate to 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 approximate 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 (Gamma alpha 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.
Indexed BySCI
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000506012000041
Citation statistics
Cited Times:3[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Corresponding AuthorPark, Jongho
Affiliation1.Acad Sinica, Inst Astron & Astrophys, POB 23-141, Taipei 10617, Taiwan
2.Seoul Natl Univ, Dept Phys & Astron, Seoul 08826, South Korea
3.Natl Astron Observ Japan, Mizusawa VLBI Observ, 2-21-1 Osawa, Mizusawa, Tokyo 1818588, Japan
4.Grad Univ Adv Studies SOKENDAI, Dept Astron Sci, 2-21-1 Osawa, Mitaka, Tokyo 1818588, Japan
5.Natl Astron Observ Japan, 2-21-1 Osawa, Mitaka, Tokyo 1818588, Japan
6.Kogakuin Univ Technol Engn, Acad Support Ctr, 2665-1 Nakano, Hachioji, Tokyo 1920015, Japan
7.Korea Astron & Space Sci Inst, Daejeon 34055, South Korea
8.Yonsei Univ, Dept Astron, 134 Shinchondong, Seoul 120749, South Korea
9.Univ Malaya, Dept Phys, Fac Sci, Kuala Lumpur 50603, Malaysia
10.Yamaguchi Univ, Grad Sch Sci & Technol Innovat, Yoshida 1677-1, Yamaguchi, Yamaguchi 7538512, Japan
11.Univ Sci Technol, Dept Astron Space Sci, 217 Gajeong Ro, Daejeon, South Korea
12.Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China
13.Chinese Acad Sci, Key Lab Radio Astron, Nanjing 210008, Peoples R China
14.MIT, Haystack Observ, 99 Millstone Rd, Westford, MA 01886 USA
15.Univ Chinese Acad Sci, 19A Yuquanlu, Beijing 100049, Peoples R China
16.Kyung Hee Univ, Dept Astron & Space Sci, Yongin 17104, Gyeonggi Do, South Korea
17.Toyo Univ, Bunkyo Ku, 5-28-20 Hakusan, Tokyo 1128606, Japan
Recommended Citation
GB/T 7714
Park, Jongho,Hada, Kazuhiro,Kino, Motoki,et al. Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification[J]. ASTROPHYSICAL JOURNAL,2019,887(2):27.
APA Park, Jongho.,Hada, Kazuhiro.,Kino, Motoki.,Nakamura, Masanori.,Hodgson, Jeffrey.,...&Hagiwara, Yoshiaki.(2019).Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification.ASTROPHYSICAL JOURNAL,887(2),27.
MLA Park, Jongho,et al."Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification".ASTROPHYSICAL JOURNAL 887.2(2019):27.
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