In a first, scientists have detected stars forming within powerful winds of material blasted out from supermassive black holes at the cores of galaxies located about 600 million light-years from Earth. The discovery has many consequences for understanding galaxy properties and evolution.
Astronomers used the MUSE and X-shooter instruments on the Very Large Telescope (VLT) at European Southern Observatory (ESO)’s Paranal Observatory in Chile to study an ongoing collision between two galaxies, known collectively as IRAS F23128-5919, that lie around 600 million light-years from Earth.
The group observed the colossal winds of material – or outflows – that originate near the supermassive black hole at the heart of the pair’s southern galaxy, and have found the first clear evidence that stars are being born within them. Such galactic outflows are driven by the huge energy output from the active and turbulent centres of galaxies.
Supermassive black holes lurk in the cores of most galaxies, and when they gobble up matter they also heat the surrounding gas and expel it from the host galaxy in powerful, dense winds. “Astronomers have thought for a while that conditions within these outflows could be right for star formation, but no one has seen it actually happening as it’s a very difficult observation,” said Roberto Maiolino from the University of Cambridge in the UK.
“Our results are exciting because they show unambiguously that stars are being created inside these outflows,” said Maiolino. The group set out to study stars in the outflow directly, as well as the gas that surrounds them. By using two of the world-leading VLT spectroscopic instruments, MUSE and X-shooter, they could carry out a very detailed study of the properties of the emitted light to determine its source. The research was published in the journal Nature.