Lunch talk on Aug. 26th, 2019
Outflows driven by large-scale magnetic field from thin accretion disk and the application to the fast growth of high-z SMBHs
Speaker: Jiawen Li (SHAO)
Venue: Room 2317, SWIFAR Building
Time: 12:30 PM, Monday, 26th August, 2019
The large-scale magnetic field threading an accretion disk plays an important role in launching jets/outflows. We construct a global disk-outflow model in which the large-scale magnetic field is formed by the advection of the external field in the disk. We find that the external weak field can be efficiently amplified by several orders of magnitude. The outflow can be accelerated up to ∼0.2–0.3c from the inner region of the disk. The outflows can remove large amount of energy and angular momentum from the disk, this result in a fast radial accretion velocity and a relatively low luminosity of the disk. We find that the SMBH with several billion solar masses discovered at z ≳ 7 can indeed be grown by chaotic accretion predominantly driven by magnetic outflows from a stellar mass seed BH, while the disks are radiating at moderate luminosity (about 0.5L_Edd).