Lasers and supermassive black holes

This image, captured by the NASA/ESA Hubble Space Telescope ’s Wide Field Camera 3 (WFC3), shows a galaxy named UGC 6093. As can be easily seen, UGC 6093 is something known as a barred spiral galaxy — it has beautiful arms that swirl outwards from a bar slicing through the galaxy’s centre. It is classified as an active galaxy, which means that it hosts an active galactic nucleus , or AGN: a compact region at a galaxy’s centre within which material is dragged towards a supermassive black hole . As this black hole devours the surrounding matter it emits intense radiation, causing it to shine brightly.

But UGC 6093 is more exotic still. The galaxy essentially acts as a giant astronomical laser that spews out light at microwave, not visible, wavelengths — this type of object is dubbed a megamaser (maser being the term for a microwave laser). Megamasers such as UGC 6093 can be some 100 million times brighter than masers found in galaxies like the Milky Way .

Hubble’s WFC3 observes light spanning a range wavelengths — from the near-infrared , through the visible range, to the near-ultraviolet . It has two channels that detect and process different light, allowing astronomers to study a remarkable range of astrophysical phenomena; for example, the UV-visible channel can study galaxies undergoing massive star formation, while the near-infrared channel can study redshifted light from galaxies in the distant Universe. Such multi-band imaging makes Hubble invaluable in studying megamaser galaxies, as it is able to untangle their intriguing complexity.