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Dynamical evolution of NGC 5128

Journal Article · · Astrophys. J.; (United States)
DOI:https://doi.org/10.1086/158411· OSTI ID:6548599
It is shown that the giant radio galaxy NGC 5128 (Centaurus A) may be the partially relaxed product of the collision of a nearly prolate elliptical galaxy with a small gas-rich galaxy or intergalactic cloud. A numerical simulation of the postcollision disk of gas and dust surrounding NGC 5128 demonstrates that its observed distortion results from an interaction with the prolate gravitational field, occurring within a time of 5 x 10/sup 8/ yr (D/5 Mpc), where D is the distance to the galaxy. The gravitational field was determined by assuming a constant mass-to-light ratio in the elliptical component of the galaxy. The gravitational accelerations and potential for an arbitrary (centrally condensed) prolate mass distribution (eq. (1)) are given. The distortion time scale requires the collision hypothesis, since the disk must be recently acquired. The simulation exhibits the proper distribution of the inner and outer dust lanes as well as the proper projected positions and velocities of an apparent ring of H II regions observed by Graham. The motion of the gas and dust parallel to the major axis of NGC 5128 is apparently ungergoing viscous damping. The implications of this model for the motion of NGC 5128 and for the formation and maintenance of the double radio source of this galaxy (Centaurus A) are discussed.
Research Organization:
National Radio Astronomy Observatory, Charlottesville, VA
OSTI ID:
6548599
Journal Information:
Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 241:3; ISSN ASJOA
Country of Publication:
United States
Language:
English

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