Astronomy: Two more megamasers

The first detection of two previously undiscovered species of megamaser is reported online this week in Nature Communications. Since the late 1970s, only three types of molecules have been found to form megamasers: water, hydroxyl and formaldehyde.

Maser is an acronym for microwave amplification by stimulated emission of radiation and, in astronomy, describes a bright object that produces amplified electromagnetic waves. Megamasers are a million times more luminous than typical galactic masers and are often associated with active galactic nuclei, which are bright, compact areas at the centre of galaxies. Radiation from active galactic nuclei is currently thought to be indicative of the presence of a supermassive black hole. High-resolution observations of megamasers enable researchers to probe active galactic nuclei and estimate the masses of central supermassive black holes.

Junzhi Wang and colleagues report the detection of both silicone monoxide and methanol (SiO and CH3OH) megamasers near the centre of the Seyfert 2 galaxy, NGC1068, using the IRAM 30-meter telescope. Based on their observations they suggest that the SiO megamaser originated from a dust disk at the centre of the galaxy and that the CH3OH megamaser originated at the front of a shock wave. As these megamaser detections are preliminary, further confirmation will be required before information about host galaxies can be inferred.