Abstracts:
Astronomical masers are the celestial analogue of the now ubiquitous laboratory masers and lasers. Since their discovery more than 40 years ago, astronomical masers have been used extensively to probe the physics and dynamics of many different environments, ranging from circumstellar envelopes and molecular clouds to the circumnuclear disk around AGNs. In addition, the precise polarimetric measurements of maser radiation hold the promise of revealing the geometry of the elusive magnetic field in the masing medium. In this talk I will concentrate on the physical basics of astronomical masers, in particular the similarities and differences between laboratory and astronomical masers. I will present our recent theoretical work on a reformulation of the semiclassical description of the maser that includes explicitly the random nature of the radiation field. The new description of the maser helps to resolve the long standing controversy concerning the polarization properties of astronomical masers.
Coffee and tea will be served 20 minutes prior to the seminar.