Volume 515, June 2010
|Number of page(s)||9|
|Published online||08 June 2010|
VLBI detection of the HST-1 feature in the M 87 jet at 2 cm
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [cschang;ros]@mpifr.de
2 Departament d'Astronomia i Astrofísica, Universitat de València, 46100 Burjassot, Spain
3 Astro Space Centre of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow, Russia e-mail: email@example.com
4 Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907, USA e-mail: firstname.lastname@example.org
Accepted: 12 February 2010
Context. A bright feature 80 pc away from the core in the powerful jet of M 87 shows highly unusual properties. Earlier radio, optical, and X-ray observations have shown that this feature, labeled HST-1, is superluminal, and is possibly connected with the TeV flare detected by HESS in 2005. It has been claimed that this feature might have a blazar nature because of these properties.
Aims. To examine whether HST-1 has a blazar-like nature, we analyzed λ2 cm VLBA archival data from dedicated full-track observations and the 2 cm survey/MOJAVE VLBI monitoring programs performed between 2000 and 2009.
Methods. We studied the subparsec scale structure of M 87 jet by using wide-field imaging techniques, after checking different weighting of the interferometric visibilities as a function of distance. The HST-1 region was imaged at milliarcsecond resolution.
Results. We present the first 2 cm VLBI detection of HST-1 in observations performed between early 2003 and early 2007, and analyze its evolution with time. Using the detections of HST-1, we find that the projected apparent speed is 0.61 ± 0.31c. A comparison of the VLA and VLBA flux densities of this feature indicates that it is mostly resolved on milliarcsecond scales. This feature is optically thin (α ~ -0.8 for ) between λ2 cm and λ20 cm.
Conclusions. We do not find evidence that HST-1 has a blazar nature.
Key words: radio continuum: galaxies / techniques: high angular resolution / techniques: interferometric / galaxies: active / galaxies: jets
© ESO, 2010
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.