1 October: Emmy Escott

Speaker: Emmy Escott (Durham University)

Date: Wednesday 1 October 2025

Time: 15:00

Location: Physics 3.21

Strap on your Boötes: Unveiling AGN Feedback through High Resolution Morphological Studies with LOFAR-VLBI

How AGN feedback operates is one of the unsolved mysteries plaguing modern day astronomy. AGN outflows could explain how this feedback operates and, to investigate this, I use the [O III] emission line as a tracer of ionised outflows. In this talk, I will present results exploring the link between low-frequency radio emission, using the LOFAR Two-meter Sky Survey (LoTSS) Deep Fields at 144 MHz with 6” resolution, and [O III] kinematics measured from SDSS spectroscopy for a sample of optically selected AGN. We find, for example, that radio detected AGN are more likely to host an [O III] outflow compared to radio non-detected AGN.

To further link outflows to low-frequency radio emission, we harness the power of widefield VLBI (Very Long Baseline Interferometry) processing and imaging by incorporating the international stations of LOFAR into the data reduction process, to obtain sub-arcsecond resolution radio images. I will present the first high-resolution 144 MHz image of the Boötes Deep Field, highlighting the main challenges that had to be overcome during the complex data reduction process required to create such an image.

Using the new sub-arcsecond resolution images of the optically selected AGN sample, we can now investigate their kpc-scale radio emission. Our results show that AGN detected on both large (6”) and small (0.3”) scales are more likely to host an [O III] outflow in comparison to AGN only detected on large scales. This suggests that the connection between ionised outflows and kpc-scale radio emission is predominantly AGN-driven, whereas AGN without an outflow are dominated by diffuse radio emission, likely to be associated with star formation.