Title: Polarisation of submillimetre lines from interstellar medium,
Abstract: Magnetic fields play important roles in many astrophysical processes.
However, there is no universal diagnostic for the magnetic fields in the
interstellar medium (ISM) and each magnetic tracer has its limitation. Any new
detection method is thus valuable. Theoretical studies have shown that
submillimetre fine-structure lines are polarised due to atomic alignment by
Ultraviolet (UV) photon-excitation, which opens up a new avenue to probe
interstellar magnetic fields. We will, for the first time, perform synthetic
observations on the simulated three-dimensional ISM to demonstrate the
measurability of the polarisation of submillimetre atomic lines. The maximum
polarisation for different absorption and emission lines expected from various
sources, including Star-Forming Regions (SFRs) are provided. Our results
demonstrate that the polarisation of submillimetre atomic lines is a powerful
magnetic tracer and add great value to the observational studies of the
submilimetre astronomy.