Past Seminars

Date:  Wednesday, November 4, 2026

Time: 09:00 UTC

Speaker: Dr. Catherine Hale

Affiliation: University of Edinburgh

Title: Radio Continuum Surveys: Understanding the Evolution of Star Formation and AGN Activity with the MIGHTEE Survey

Abstract:

In the last 5-10 years, deep radio continuum surveys with telescopes such as MeerKAT have been transforming our knowledge of the extragalactic radio sky both over wider areas and in deeper, smaller fields that have an abundance of multi-wavelength information. Through tracing synchrotron emission associated with both star formation in galaxies and active galactic nuclei (AGN), radio continuum surveys naturally provide a unique view on the Universe which trace two processes that are crucial for galaxy evolution. This is all without the effects of dust obscuration, which can plague other wavelengths. One such survey that has helped progress our understanding of the evolution of star formation and AGN activity is the MIGHTEE survey (Jarvis+ 2016, Hale+ 2025). In this talk, I will present the MIGHTEE survey and describe how the combination of radio continuum, spectral line and polarization are crucial to tracing a number of the complex factors which are crucial in shaping galaxies. My talk will highlight some of the key science outputs from MIGHTEE to date, alongside giving a preview of the exciting science which is still to come. This will include work tracing the unobscured cosmic star formation history, how AGN which accrete via different modes compare, and the role on environment in shaping galaxies. I will continue to how upcoming complementary spectroscopic and multi-wavelength surveys (e.g. from 4MOST) will transform the science capabilities possible to study the interplay of star formation, AGN activity and environment in driving galaxy evolution across cosmic time.

Date:  Wednesday, October 14, 2026

Time: 09:00 UTC

Speaker: Dr. Frederick Gent

Affiliation: Aalto University / Stockholm University / Nordita

Title: The transitions between small-scale and large-scale dynamos in the interstellar medium

Abstract: 

Magnetic fields play a critical role in the structure and evolution of galaxies, contributing equivalent typical energy to each of thermal, kinetic and cosmic ray energies in the interstellar medium (ISM). To acquire such strength, as observed, necessitates galactic dynamos which amplify the field at multiple scales in both time and space. The small-scale (or turbulent) dynamo (SSD) in the ISM acts fast within, at most, a few megayears and at scales smaller than that of the primary drivers of the turbulence (typically supernovae – SNe). Due to the multiphase structure of the ISM, spanning over seven orders of magnitude in temperature and the sporadic nature of SN forcing and heating, the dominant eigenmode of the SSD can shift between phases and over time. Comparison with simulations of numerically forced isothermal SSD and dynamo theory are therefore challenging.

The large-scale (or mean-field) dynamo (LSD) acts at kiloparsec scales and over timescales exceeding a gigayear. The primary driver is galactic shear aligning the turbulent magnetic field to its orbit. Simulations that have successfully modelled galactic LSD with mean-fields of strength and structure consistent with observed magnetic fields, typically have much weaker turbulent fields than observed. The LSD and SSD need to be present to effectively model how the galactic magnetic field arises of correct morphology and relative strength. We discuss our efforts to understand and quantify the actions and interactions of the SSD and LSD.