Astronomy & Astrophysics Seminar: Is there an ADAF transition in very low luminosity AGN?

Abstract:

The very low luminosity AGN, NGC 3147, with L/L_Edd = 10^-4, was considered to be a true type 2 AGN, i.e. an AGN which lacks a Broad Line Region (in contrast with regular type 2 AGN, where the BLR  is simply obscured).  Our recent HST observation  managed to exclude the host galaxy light, and revealed that the BLR is actually there,  at the expected luminosity and position. The BLR is extremely compact, and indicates a thin disk of cold gas extending below 100 gravitational radii, which is most likely the accretion disk itself. Such low luminosity AGN are commonly believed to be powered by Advection Dominated Accretion Flows, which form a thick hot dilute gas, in contrast with the observations. Further possible followups will be briefly described.

Seminar Organizer: Dr. Omer Bromberg