Grant: Discovery Grants Program - Individual

Masers are ubiquitous in the universe. Since their discovery in the interstellar medium (ISM) nearly 60 years ago masers have been detected in a wide range of environments and physical conditions. Just as is the case for lasers in terrestrial laboratories, corresponding studies quickly moved on from the initial quest for a better understanding of a novel and intricate physical phenomenon to using the maser action as an indispensable tool for characterizing systems of all kinds. To name a few examples, in astrophysics masers are now routinely used to accurately map Galactic and extra-galactic distances, study the structure, kinematics and magnetic fields in regions where stars are currently forming, probe the circumstellar envelopes of old stars, and even measure the expansion of the universe in a manner independent from more commonly used techniques. However, despite the large number of studies performed and results obtained using them, masers sources still hold a few mysteries that require attention. In particular, strong and abrupt intensity flares often display puzzling behaviours difficult to explain within the framework of maser theory. This shortcoming in knowledge is a limitation for our understanding and characterization of the environments home to these events, which, given the extraordinary flaring manifestations, are likely to host physical conditions that are different from those normally found elsewhere in the ISM. In recent years my research endeavours were largely focused on explaining these intense radiation flares using a fundamental radiation process introduced in a seminal paper by R. H. Dicke in 1954. Whenever conditions such as those found in a maser gas prevail in the ISM, Dicke showed that the commonly assumed independent spontaneous emission process for the molecules in the gas is replaced by a powerful transient phenomenon he termed "superradiance." With superradiance molecules become entangled and work as a single unit by emitting a cascade of photons at exceedingly high rates and intensities, resulting in powerful coherent bursts of radiation. This phenomenon has been studied and used in laboratories for several decades but, intriguingly, astronomers remained largely unaware of this radiation process until the recent work performed by my research group. With this proposal I plan to expand on this research by combining this line of analysis with the expertise in magnetic field studies I developed at earlier stages of my career. Using existing and new superradiance diagnoses, as well as by accounting for propagation effects on the polarization state of spectral lines, I will precisely characterize the environment of maser-hosting sources and their magnetic fields during flaring events. The objectives described in this proposal push the boundaries of knowledge and promise to add layers to our growing understanding of the interstellar medium.