Astronomy & Astrophysics Seminar: Direct Evidence for Radiatively Accelerating Quasar Outflows

Zoom: https://tau-ac-il.zoom.us/j/81239615480?pwd=qynx9sGBcqWlo2fNUEbZrq1VibGgwM.1

Abstract:

Quasar outflows play a fundamental role in galaxy evolution, serving as the primary mechanism for quenching star formation and unbinding interstellar gas from host galaxies. This large-scale feedback is expected to be driven by fast winds launched near the central supermassive black hole (SMBH) . While outflow speeds exceeding 10, 000 km/s have been routinely observed for 50 years, the physical mechanism driving them remains a mystery, largely because their acceleration phase has eluded observations. Using HST observations, in 2017 we detected the largest acceleration for a quasar outflow, observed to date. From −19, 550 km/s in 2011 to −21, 040 km/s in 2017 (∆v = −1490 km/s).

We then used a well-known radiation-driven wind model (7) to predict the future acceleration of the outflow. In January 2026 we obtained a third HST observation epoch that showed a further velocity increase to −22, 390 km/s. This ∆v = −1350 km/s is within 5% of the predicted value for this epoch. Thus, providing the first conclusive evidence for the nature of the acceleration mechanism of quasar outflows: Line-driven radiation acceleration.

Seminar Organizer: Dr. Jonathan Stern