Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-07-24
Astronomy and Astrophysics
Astrophysics
12 pages, 4 figures
Scientific paper
10.1086/317064
The presence of optical synchrotron jets in radio galaxies is relatively rare. Here, we show that of the nearest five FR-I 3CR radio galaxies showing optical jets, {\it four} show evidence for almost circular, presumably face-on, dust disks. This is strong support for the two-fold idea that (\romannumeral1) jets emerge close to perpendicular to inner gas disks and (\romannumeral2) optical non-thermal synchrotron emission is seen only when the jet points towards the observer. The implied critical angle to the line-of-sight is approximately 30 - $40^{\circ}$, i.e. if the angle of the jet to the line-of-sight is less than about $40^{\circ}$ we see an optical jet. The corresponding relativisitic $\gamma$ factor is $\approx 1.5$ which is consistent with current observations of jet proper motion that show a range up to $\gamma \sim 6$ for M87. The relatively low speeds implied by $\gamma \approx 1.5$ may be due to a global deceleration of the jet as in unified theories, or else to stratification within the jet. Unresolved nuclei are common in the optical. Their luminosities are also consistent with the beaming concept when compared to inclination inferred from the dust lanes. The disk sizes are typically several hundred parsecs, to kiloparsec size. The galaxy with an optical jet that does not show a face-on disk, M87, instead has more complex radial dust and ionized gas filaments.
Baum Stefi A.
Biretta John
Macchetto Ferdinando D.
Martel Andre R.
Sparks William B.
No associations
LandOfFree
Face-on Dust Disks in Galaxies with Optical Jets does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Face-on Dust Disks in Galaxies with Optical Jets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Face-on Dust Disks in Galaxies with Optical Jets will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-106010