Speaker
Description
Giant radio galaxies are a spectacular and gargantuan form of AGN, often living in under-dense environments and hosting jets that have been switched on for extended periods. Many seem ancient, with estimated ages over 100 Myr, and/or exhibit complex characteristics, suggesting multiple epochs of activity over their lifetime. In particular, studying giant radio galaxies with signs of young, restarted jets provides a key window into jet triggering and feedback mechanisms.
These jets play a pivotal role in the evolution of both the host galaxy and the ambient medium, as they may trigger and/or inhibit star formation, drive the mixing of gas and dust internally to the galaxy, drive outflows into the ambient medium, and even sufficiently cut off the supply of infalling material that fuels the central engine.
In this talk I will present the results of a multi-wavelength observational campaign studying the nearby giant radio galaxy MSH05–22, which shows highly asymmetric radio lobes. Our campaign covers radio frequencies from 70 MHz to 40 GHz using the Murchison Widefield Array (MWA), the Australian Square Kilometre Array Pathfinder (ASKAP), and the Australia Telescope Compact Array (ATCA) as well as the MeerKAT radio telescope in South Africa, combined with optical integral field unit (IFU) spectroscopic observations.
Put together, our exquisite dataset paints the picture of periodic activity from MSH05-22, from which we study the duty cycle of the AGN, the processes by which the central engine was fed, and the feedback from the AGN into the ambient medium. On the largest scales, the megaparsec-scale lobes are diffuse and steep spectrum with no hotspots, indicating they are no longer powered by fresh activity and have estimated ages well over 100 Myr. On intermediate scales, our radio data show evidence of asymmetric jets on scales up to around 100 kpc with a highly-ordered magnetic field. On small scales, the radio core associated with the central engine shows complex spectral structure suggesting different components tracing historic activity, as well as a high-frequency break indicating that the central engine switched off some 8 Myr ago.
Our IFU and MeerKAT HI observations show evidence of a recent interaction between MSH05-22 and its near neighbours, with neutral inflow of material onto the dominant elliptical galaxy as well as extended HI emission spanning the system. This interaction and inflow triggered an epoch of star formation as recently as 10 Myr ago, as well as likely triggering the most recent episode of AGN activity. Overall MSH05-22 is a highly rich system which provides many insights into the life cycles of these most giant and most ancient of radio galaxies.
| What is your career stage? | Non-tenured scientist (post PhD) |
|---|---|
| Which telescopes do you use / are you affiliated with? | MWA, ASKAP, MeerKAT, ATCA, LOFAR |
