OH masers in the Milky Way and Local Group galaxies in the SKA era

TL;DR

The paper discusses how SKA deep surveys will revolutionize the study of OH masers, enabling discoveries in the Milky Way and Local Group galaxies, and providing new insights into star formation, galactic structure, and magnetic fields.

Contribution

It predicts the detection of over 20,000 OH masers with SKA, including in Local Group galaxies, and highlights new applications and transitions for studying star formation and galactic environments.

Findings

Over 20,000 new OH masers expected from SKA surveys

First detection of large numbers of OH masers in Local Group galaxies

Access to additional maser transitions like excited OH and methanol

Abstract

The intense line emission of OH masers is a perfect tracer of regions where new stars are born aswell as of evolved stars, shedding large amounts of processed matter into the interstellar medium. From SKA deep surveys at 18 cm, where the maser lines from the ground-state of the OH molecule arise, we predict the discovery of more than 20000 sources of stellar and interstellar origin throughout the Galaxy. The study of this maser emission has many applications, including the determination of magnetic field strengths from polarisation measurements, studies of stellar kinematics using the precisely determined radial velocities, and distance determinations from VLBI astrometry. A new opportunity to study shocked gas in different galactic environments is expected to arise with the detection of lower luminosity masers. For the first time, larger numbers of OH masers will be detected in Local Group galaxies. New insights are expected in structure formation in galaxies by comparing maser populations in galaxies of different metallicity, as both their properties as well as their numbers depend on it. With the full capabilities of SKA, further maser transitions such as from excited OH and from methanol will be accessible, providing new tools to study the evolution of star-forming regions in particular.