The black hole at the centre of a nearby galaxy is growing exceptionally fast, and is producing a burst of radio emission that has never been observed before.

While most radio transients last only days or weeks, the spiral galaxy SDSS J110546.07+145202.4 has been shining very brightly in radio light for several years – the first source of its kind.

An international team led by Stefanie Komossa from the Max Planck Institute for Radio Astronomy (MPIfR) studied this unique galaxy using new observations and archival data, including those from our Australia Telescope Compact Array. The results were published in The Astrophysical Journal.

The intensity of the galaxy’s radio emission has increased more than 20-fold in a short period of time and shows no signs of weakening. For over eight years now, the galaxy has been shining exceptionally brightly in the radio regime, about ten quadrillion times as intensely as our Sun.

The source of the radiation is located near the black hole at the galaxy’s centre. This black hole has a comparatively low mass, which is increasing exceptionally fast, however, through the accretion of matter.

Luminous radio radiation from rapidly growing, lightweight black holes is rare. The transition into a long-lasting, radio bright state is even rarer: it has never been observed before. Follow-up observations with telescopes, such as the 100-meter Effelsberg telescope, ATCA, and satellites in space, all confirm the source’s unique properties.

Based on the extensive dataset, the team suspects that more matter has been falling into the black hole for several years, which in turn has triggered a jet. Why exactly more matter is falling into the black hole and why the outburst has lasted so long has not yet been conclusively determined.