Astrophysics Seminar
Reconstructing Magnetic Interstellar Structure Using ISM Polarization
Speaker: Dr. Namita Uppal (Institute of Astrophysics, Foundation for Research and Technology - Hellas, Heraklion, Greece)
Studies of the Milky Way interstellar medium (ISM) have traditionally relied on two dimensional (2D) sky projections. However, recent advancements have enabled the exploration of the third spatial dimension: distance. Gaia mission, with its precise parallax measurements of over billions of stars, has been instrumental in this progress, allowing for detailed 3D mapping of the dust density in the ISM. Yet, the current 3D reconstructions of the ISM dust distribution are leaving out an important component of the Galaxy: magnetic fields, which are ubiquitous in the ISM.
Over the past two decades, extensive efforts have focused on probing magnetic fields in both the Milky Way and external galaxies through observations of synchrotron and thermal dust emission. However, these tracers only provide LOS integrated information of the plane-of-sky (POS) component of magnetic field, making it challenging to resolve 3D structures where multiple dust clouds overlap.
On the other hand, starlight polarization offers a complementary probe. When combined with precise stellar distances information from Gaia, starlight polarization enables tomographic reconstruction of the POS component of the magnetic field, providing a unique means of resolving overlapping structures along the LOS. In this seminar, I will discuss how starlight polarization can be used to reconstruct the magnetic structure of the interstellar medium. I will also introduce TRIShUL, a newly developed tool that automatically identifies thin dust layers along the line of sight (LOS) for tomographic analysis, making it well suited for the upcoming era of large-scale polarization surveys.