Astronomical objects radiation shows some degree of polarization. In most cases, the polarized part is just a small fraction of the total radiation. However, even being a small part of total flux, it carries a wealth of information on the physical state and geometry of the source of radiation. In addition, this radiation also interacts with the intervening material and thus provide us with information on the interstellar matter. Polarimetry is an almost as traditional technique as photometry and spectroscopy in astronomical observations and has already contributed to a large degree in our understanding of astronomical sources of radiation.
While spectroscopy, photometry, and timing are techniques applied at all wavelengths, polarimetry has been so far used mainly in the radio and in the optical domains. As X and gamma-ray polarimetry establish these days, optical polarimetry has been pivotal in studying a variety of incoherent emission mechanisms, synchrotron and curvature radiation, from several types of sources: compact objects, interacting binaries, active galactic nuclei, etc. Some of these studies investigate the properties of the extreme magnetic fields around neutron stars and map the magnetic and electric field in diffuse emission environments, such as supernova remnants or pulsar-wind nebulae.
Still, polarimetry is not well spread and use among astronomers. The aim of the Toruń Summer School 2019: Polarimetry as a diagnostic tool in astronomy is to fill this gap and to introduce to the school participants the polarimetric basics and the modern techniques and instrumentation.
During one week school, the world-class experts on polarimetry will give lectures and hands-on sessions on the following topics: an introduction to polarimetry, instruments and observational techniques, methods, principles, errors calculation and propagation, polarization of interstellar matter, polarized light from exoplanets and planetary atmospheres, comets and asteroids, young stellar objects, protoplanetary disks and debris disks, as well as on magnetised stars, compact objects and AGNs and galaxies.