%0 Generic %1 citeulike:12550448 %A Hada, Kazuhiro %A Kino, Motoki %A Doi, Akihiro %A Nagai, Hiroshi %A Honma, Mareki %A Hagiwara, Yoshiaki %A Giroletti, Marcello %A Giovannini, Gabriele %A Kawaguchi, Noriyuki %D 2013 %K imported %T Innermost collimation structure of the M87 jet down to \~ten Schwarzschild radii %U http://arxiv.org/abs/1308.1411 %X We investigated the detailed inner jet structure of M87 using the Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on the multi-frequency properties of the radio core at the jet base. First, we measured a size of the core region transverse to the jet axis, defined as \$W\_c\$, at each frequency \nu, and found a relation between \$W\_c\$ and \$\nu\$ as \$W\_c(\nu) \nu^-0.71\pm0.05\$. Then, by combining \$W\_c(\nu)\$ and the frequency dependence of the core position \$r\_\rm c(\nu)\$, which was obtained by our previous study, we have constructed a collimation profile of the innermost jet \$W\_c(r)\$ down to \~10 Schwarzschild radii (\$R\_s\$) from the central black hole. We found that \$W\_c(r)\$ smoothly connects with the width profile of the outer edge-brightened, parabolic jet, and then follows a similar radial dependence down to several tens of \$R\_s\$. Closer to the black hole, the measured radial profile suggests a possible change of the jet collimation shape from the outer parabolic one, in which the jet shape tends to become more radially-oriented. This could be related to a magnetic collimation process or/and interaction with surrounding materials at the jet base. The present results shed light on the importance of higher-sensitivity/resolution imaging studies for M87 at 86, 43 and also 22 GHz, and should be examined more rigorously.

@misc{citeulike:12550448, abstract = {We investigated the detailed inner jet structure of M87 using the Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on the multi-frequency properties of the radio core at the jet base. First, we measured a size of the core region transverse to the jet axis, defined as \$W\_{\rm c}\$, at each frequency \nu, and found a relation between \$W\_{\rm c}\$ and \$\nu\$ as \$W\_{\rm c}(\nu) \propto \nu^{-0.71\pm0.05}\$. Then, by combining \$W\_{\rm c}(\nu)\$ and the frequency dependence of the core position \$r\_{\rm c}(\nu)\$, which was obtained by our previous study, we have constructed a collimation profile of the innermost jet \$W\_{\rm c}(r)\$ down to \~{}10 Schwarzschild radii (\$R\_{\rm s}\$) from the central black hole. We found that \$W\_{\rm c}(r)\$ smoothly connects with the width profile of the outer edge-brightened, parabolic jet, and then follows a similar radial dependence down to several tens of \$R\_{\rm s}\$. Closer to the black hole, the measured radial profile suggests a possible change of the jet collimation shape from the outer parabolic one, in which the jet shape tends to become more radially-oriented. This could be related to a magnetic collimation process or/and interaction with surrounding materials at the jet base. The present results shed light on the importance of higher-sensitivity/resolution imaging studies for M87 at 86, 43 and also 22 GHz, and should be examined more rigorously.}, added-at = {2019-03-25T08:20:55.000+0100}, archiveprefix = {arXiv}, author = {Hada, Kazuhiro and Kino, Motoki and Doi, Akihiro and Nagai, Hiroshi and Honma, Mareki and Hagiwara, Yoshiaki and Giroletti, Marcello and Giovannini, Gabriele and Kawaguchi, Noriyuki}, biburl = {https://www.bibsonomy.org/bibtex/2b275e28d021f09e44a7976f6a16bfc6d/ericblackman}, citeulike-article-id = {12550448}, citeulike-linkout-0 = {http://arxiv.org/abs/1308.1411}, citeulike-linkout-1 = {http://arxiv.org/pdf/1308.1411}, day = 6, eprint = {1308.1411}, interhash = {9a7ee10379cf527931afebbd27da518e}, intrahash = {b275e28d021f09e44a7976f6a16bfc6d}, keywords = {imported}, month = aug, posted-at = {2013-08-10 21:57:42}, priority = {2}, timestamp = {2019-03-25T08:20:55.000+0100}, title = {{Innermost collimation structure of the M87 jet down to \~{}ten Schwarzschild radii}}, url = {http://arxiv.org/abs/1308.1411}, year = 2013 }