Michael Janssen (MPIfR/Radboud University)

Michael Janssen Colloquium: Latest results from the Event Horizon Telescope: Zooming into the heart of Cen A

Online

Abstract

Centaurus A is the closest radio galaxy to Earth and has been studied extensively as a laboratory for AGN feedback and potential UHECR source after its discovery as one of the first extragalactic radio sources in 1949.
I will present the results from our EHT observations of this southern source. Compared to previous VLBI studies, we have imaged the AGN jet of Cen A at a 16x sharper resolution and 10x higher observing frequency. This allows us to probe the launching region of an extragalactic radio jet on sub-lightday scales.
We can directly compare our image to VLBI observations of M87 at a lower frequency, as both probe the same size scales in terms of gravitational radii. Based on the similarity of these jets, we show that our observations provide further support for the fundamental plane of black hole activity in an intermediate mass regime. From the location of the resolved radio core in Cen A, we predict the source's black hole shadow to be visible at THz frequencies, which marks Cen A for future high-frequency space VLBI missions.
I will conclude with an outlook of our next observational and modeling steps.