Aims: We aim to constrain the structural variations within the HST-1 region downstream of the radio jet of M 87, in general as well as in connection to the episodes of activity at very high energy (VHE). Methods: We analyzed and compared 26 VLBI observations of the M 87 jet, obtained between 2006 and 2011 with the Very Long Baseline Array (VLBA) at 1.7 GHz and the European VLBI Network (EVN) at 5 GHz. Results: HST-1 is detected at all epochs; we model-fitted its complex structure with two or more components, the two outermost of which display a significant proper motion with a superluminal velocity around ~4 c. The motion of a third feature that is detected upstream is more difficult to characterize. The overall position angle of HST-1 has changed during the time of our observations from -65° to -90°, while the structure has moved by over 80 mas downstream. Our results on the component evolution suggest that structural changes at the upstream edge of HST-1 can be related to the VHE events.
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Titolo: | The kinematic of HST-1 in the jet of M 87 |
Autori: | M., Giroletti; K., Hada; G., Giovannini; C., Casadio; M., Beilicke; Cesarini, Andrea; C., Cheung; A., Doi; H., Krawczynski; M., Kino; N., Lee; H., Nagai |
Autori Unitn: | |
Titolo del periodico: | ASTRONOMY & ASTROPHYSICS |
Anno di pubblicazione: | 2012 |
Codice identificativo Scopus: | 2-s2.0-84856856005 |
Codice identificativo ISI: | WOS:000300614100163 |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1051/0004-6361/201218794 |
Handle: | http://hdl.handle.net/11572/100166 |
Appare nelle tipologie: | 03.1 Articolo su rivista (Journal article) |