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PARSEC-SCALE IMAGING OF THE RADIO-BUBBLE SEYFERT GALAXY NGC 6764
journal contribution
posted on 2023-06-08, 09:59 authored by P Kharb, Ananda Hota, J H Croston, M J Hardcastle, C P O'Dea, R P Kraft, D J Axon, A RobinsonWe have observed the composite active galactic nucleus (AGN)-starburst galaxy NGC 6764 with the Very Long Baseline Array at 1.6 and 4.9 GHz. These observations have detected a "core-jet" structure and a possible weak counterjet component at 1.6 GHz. The upper limits to the core and jet (1.6-4.9 GHz) spectral index are 0.6 and 0.3, respectively. Taken together with the high brightness temperature of similar to 10(7) K for the core region, the radio emission appears to be coming from a synchrotron jet. At a position angle of similar to 25 degrees, the parsec-scale jet seems to be pointing closely toward the western edge of the southern kpc-scale bubble in NGC 6764. A real connection between the parsec-and sub-kpc-scale emission would not only suggest the presence of a curved jet, but also a close link between the AGN jet and the radio bubbles in NGC 6764. We demonstrate that a precessing jet model can explain the radio morphology from parsec to sub-kpc scales, and the model best-fit parameters of jet speed and orientation are fully consistent with the observed jet-to-counterjet surface brightness ratio. The jet however appears to be disrupted on scales of hundreds of parsecs, possibly due to interaction with and entrainment of the interstellar medium gas, which subsequently leads to the formation of bubbles. The jet energetics in NGC 6764 suggest that it would take 12-21 Myr to inflate the (southern) bubble. This timescale corresponds roughly to the starburst episode that took place in NGC 6764 about 15-50 Myr ago, and could be indicative of a close connection between jet formation and the starburst activity in this galaxy.
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Publication status
- Published
Journal
Astrophysical JournalISSN
0004-637XPublisher
Institute of PhysicsExternal DOI
Issue
1Volume
723Page range
580-586Department affiliated with
- Physics and Astronomy Publications
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- No
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- Yes
Legacy Posted Date
2012-02-06Usage metrics
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