Replicating sky emission in labs for astronomers

The magnetic field (B-field) plays a crucial role in the process of star formation. To observe molecular cloud B-fields, astronomers rely on submm dust emission observation. This is because dust grains in molecular clouds align with B-field. However, polarized signals are obscured by the intense non-polarized emission from the Earth’s atmosphere. To overcome this challenge, sophisticated instruments (polarimeters) and strategic observation methods are necessary. However, these tools have not undergone fundamental advancements for two decades because new technologies can only be tested on remote and rare submm telescopes. Thus, we are motivated to develop the Sky Noise Simulator (SNoS). Here we present how we use SNoS to produce a beam that consists of predominantly non-linearly polarized noise and a faint linearly polarized signal. This combined beam is then directed into the instrument under test (IUT). With SNoS, polarimeters can be conveniently tested in the laboratory without moving to telescopes.