PhD colloquium: Timea Kovács

/PhD colloquium: Timea Kovács

PhD colloquium: Timea Kovács

Event Details

PhD colloquium, location: Auditorium 0.02, MPIfR

Timea Kovács

The redshift evolution of galactic-scale magnetic fields

Magnetic fields play an important role in galaxy evolution, from processes such as gas dynamics and star formation to galactic outflows. However, the redshift evolution of galactic-scale magnetic fields is not well constrained, both observations and theoretical predictions are lacking, with only a handful of direct magnetic field strength measurements in distant galaxies. In my talk, I will present my results from both radio polarimetric observations and synthetic observations made with the IllustrisTNG50 simulation. First, I will present the analysis of broadband (1 – 8 GHz) spectro-polarimetric Very Large Array observations of two lensing systems (B1600+434 and B0218+357). Using these, we measured the halo magnetic field of a distant galaxy at z=0.414 (corresponding to 4.4 Gyr ago) for the first time with a strength of 1.2 – 1.8 uG, and found an axisymmetric disk field of 2 – 20 uG in a lensing galaxy at z=0.685 (6.3 Gyr ago), in agreement with the magnetic field strength and structure of nearby galaxies. Then, I will show how the observables of magnetic fields evolve over redshift using 16 500 galaxies at redshifts of 0 < z < 2 from the state-of-the-art cosmological magneto-hydrodynamic simulation IllustrisTNG50. I explore two methods used to obtain cosmic magnetic field strengths: deriving the magnetic field strength of intervening galaxies in front of polarized background quasars and deriving the magnetic field strength of the IGM by utilizing FRBs. In the near future, we expect the number of known lensing systems, quasars with intervening galaxies, and polarized FRBs to dramatically increase by tens of thousands of systems due to new radio surveys and telescopes. The results I am presenting demonstrate how the lensing method can be applied to different galaxies, and predict measuring the magnetic field strength of the IGM with a 2 rad m^-2 precision using FRBs will be possible in under 10 years.