Kinematics of the M87 Jet in the Collimation Zone: Gradual Acceleration and Velocity Stratification

• Main Authors: 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
• Format: Article
• Published: IOP Publishing 2019
• Subjects: Q Science (General); QB Astronomy; QC Physics
• Online Access: http://eprints.um.edu.my/23763/; https://doi.org/10.3847/1538-4357/ab5584

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...