Galactic Structure and Evolution: What 3D Magnetic Field Observations Are Revealing
Speaker: Mehrnoosh Tahani
Abstract:
Recent observations have significantly advanced our understanding of the three-dimensional (3D) structure and evolution of the interstellar medium (ISM). To fully comprehend ISM evolution, however, it is necessary to study interstellar magnetic fields, which play a pivotal role in the evolution of the galaxy and the formation of stars. Despite their importance, our understanding of magnetic fields in the ISM is limited due to significant challenges in observing them in 3D. In this talk, I will briefly discuss how we overcame the challenges in determining the 3D magnetic fields associated with giant molecular clouds. These 3D fields enabled us to propose step-by-step scenarios to explain the formation of these clouds, revealing previously undiscovered interstellar structure. Our approach involves a novel technique based on Faraday rotation measurements to detect the line- of-sight component of magnetic fields. We then integrate these line-of-sight measurements with plane-of-sky magnetic field observations to examine the 3D magnetic field morphology associated with the clouds. Finally, we employ Galactic magnetic field models to reconstruct the complete 3D magnetic field morphologies of these clouds, including their previously unknown direction. These 3D studies provide novel constraints on theories for the formation and evolution of star-forming clouds.