Events Daily

Tuesday, May 9, 2023

New Models of the Magnetic Field of the Galaxy
Michael Unger, Karlsruhe Institute of Technology
Event Type: Astro Seminar
Time: 2:00 PM - 3:00 PM
Location: 726 Broadway, 940, CCPP Seminar
Abstract: Galaxies are known to be permeated by large-scale magnetic fields with energy densities comparable to the turbulent and thermal energy densities of the interstellar mediums. A good knowledge of the global structure of these fields is important to understand their origin and to infer their effect on galactic dynamics and the propagation of charged particles in galaxies. In this talk I will present new studies of the global structure of the magnetic field of our Galaxy based on the analysis of recent new full-sky data of extragalactic rotation measures and the final polarized intensity maps from WMAP and Planck. Our analysis employs the latest models for the thermal electron density tuned to the dispersion measures of Galactic pulsars and state-of-the-art cosmic-ray electrons models, needed to predict the rotation measures and synchrotron emission from the Galaxy, respectively. We have developed new divergence-free parametric models of the global structure of the magnetic field, with parameters tuned to the data. As a result, I will present a major revision of the widely-used Jannson-Farrar 2012 model of the magnetic field of the Galaxy. In addition to our fiducial magnetic field model, we produced a suite of alternative models that fit the data with similar quality, but use different model assumption. This suite of models is then used to place a lower limit on the model uncertainties. As an application, we will discuss the uncertainties of the predicted deflection of the predicted deflection of ultrahigh-energy cosmic rays in the Galaxy.