Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-10-20
Astronomy and Astrophysics
Astrophysics
20 pages, 5 figures. Accepted for publication in The Astrophysical Journal
Scientific paper
10.1086/306951
The ultraluminous infrared galaxy Arp 220 has been observed at 0.5" resolution in CO(2-1) and 1 mm continuum using the newly expanded Owens Valley Millimeter Array. The CO and continuum peaks at the double nuclei and the surrounding molecular gas disk are clearly resolved. We find steep velocity gradients across each nucleus (dV ~ 500 km/s within r= 0.3") whose directions are not aligned with each other and with that of the outer gas disk. We conclude that the double nuclei have their own gas disks (r ~ 100 pc). They are counterrotating with respect to each other and embedded in the outer gas disk (r ~ 1 kpc) rotating around the dynamical center of the system. The masses of each nucleus are M_dyn > 2* 10^9 M_sun based on the CO kinematics. Although there is no evidence of an old stellar population in the optical or near infrared spectroscopy of the nuclei (probably due to the much brighter young population), it seems likely that these nuclei were 'seeded' from the pre-merger nuclei in view of their counterrotating gas kinematics. The gas disks probably constitute a significant fraction (~ 50 %) of the mass in each nucleus. The CO and continuum brightness temperatures imply that the nuclear gas disks have high area filling factors (~ 0.5-1) and have extremely high visual extinctions (Av ~ 1000 mag). The molecular gas must be hot (>= 40 K) and dense (>= 10^4-5 cm^-3), given the large mass and small scale-height of the nuclear disks. The continuum data suggest that the large luminosity (be it starburst or AGN) must originate within 100 pc of the two nuclear gas disks which were presumably formed through concentration of gas from the progenitor outer galaxy disks.
Crosas Merce
Genzel Reinhard
Sakamoto Kanako
Scoville Nicholas Z.
Tacconi Linda J.
No associations
LandOfFree
Counterrotating Nuclear Disks in Arp 220 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 Counterrotating Nuclear Disks in Arp 220, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Counterrotating Nuclear Disks in Arp 220 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-355953