Projects per year
Abstract
Observational studies of collimation in jets in active galactic nuclei (AGN) are a key to understanding their formation and acceleration processes. We have performed an automated search for jet shape transitions in a sample of 367 AGN using VLBA data at 15 and 1.4 GHz. This search has found 10 out of 29 nearby jets at redshifts z < 0.07 with a transition from a parabolic to conical shape, while the full analysed sample is dominated by distant AGN with a typical z ≈ 1. The ten AGN are UGC 00773, NGC 1052, 3C 111, 3C 120, TXS 0815−094, Mrk 180, PKS 1514+00, NGC 6251, 3C 371, and BL Lac. We conclude that the geometry transition may be a common effect in AGN jets. It can be observed only when sufficient linear resolution is obtained. Supplementing these results with previously reported shape breaks in the nearby AGN 1H 0323+342 and M87, we estimate that the break occurs at 10 5–10 6 gravitational radii from the nucleus. We suggest that the jet shape transition happens when the bulk plasma kinetic energy flux becomes equal to the Poynting energy flux, while the ambient medium pressure is assumed to be governed by Bondi accretion. In general, the break point may not coincide with the Bondi radius. The observational data support our model predictions on the jet acceleration and properties of the break point.
Original language | English |
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Pages (from-to) | 3576-3591 |
Number of pages | 16 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 495 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2021 |
MoE publication type | A1 Journal article-refereed |
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Dive into the research topics of 'A transition from parabolic to conical shape as a common effect in nearby AGN jets'. Together they form a unique fingerprint.Projects
- 5 Finished
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Physics of Black Hole-Powered Jets
Savolainen, T. (Principal investigator) & Chamani Velasco, W. (Project Member)
01/09/2017 → 31/08/2019
Project: Academy of Finland: Other research funding
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Physics of Black Hole-Powered Jets
Savolainen, T. (Principal investigator)
01/01/2016 → 31/08/2019
Project: Academy of Finland: Other research funding
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Physics of Black Hole-Powered Jets
Savolainen, T. (Principal investigator), Chamani Velasco, W. (Project Member), Kiehlmann, S. (Project Member) & Suortti, J. (Project Member)
01/01/2016 → 31/08/2017
Project: Academy of Finland: Other research funding
Equipment
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Metsähovi Radio Observatory
Tammi, J. (Manager)
School of Electrical EngineeringFacility/equipment: Facility