black hole
March 30, 2017

Black holes don’t just destroy stars– they create them

Supermassive black holes fire out powerful jets of material, and new research published in the journal Nature has revealed, for the first time, stars developing in this extreme environment.

The study team said their revelation has numerous repercussions for comprehending galactic properties and growth.

Using the Very Large Telescope (VLT) at the European Southern Observatory’s Paranal Observatory in Chile, the study team was able to observe a two-galaxy collision, known jointly as IRAS F23128-5919, about 600 million light-years from Earth. The group viewed the massive jets of material, or outflows, that appear close to the supermassive black hole in the middle of the pair’s southern galaxy, and have discovered the first distinct evidence of stars forming inside these jets.

Research has shown these massive jets are powered by the huge energy released from the energetic hearts of galaxies. Supermassive black holes sit in the centers of most galaxies, and when they eat up matter, they also warm up the nearby gas and discharge it in potent, lustrous 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,” study leader Roberto Maiolino, from the University of Cambridge in the United Kingdom, said in a news release. “Our results are exciting because they show unambiguously that stars are being created inside these outflows.”

Specialized Light-Sensing Equipment

Through the use of two VLT spectroscopic instruments, MUSE and X-shooter, the study team conducted a very comprehensive study of the qualities of the light being emitted from the colliding galaxies.

Radiation from young stars has been shown to make gas clouds in the area glow in a specific way, and the extraordinary sensitivity of X-shooter permitted the team to eliminate other causes of the light they saw, including gas jolts or the nucleus of the galaxy.

The group then made a direct identification of a very young stellar population in the jets. These stars are believed to be younger than a few tens of millions of years old, and initial investigation has indicated that they are warmer and more brilliant than stars established in less extreme conditions.

The scientists also established the direction and speed of these stars. The light from most of the region’s stars suggested they are moving quickly away from the galaxy center, which would make sense for items captured in a jet of fast-moving material.

“The stars that form in the wind close to the galaxy centre might slow down and even start heading back inwards, but the stars that form further out in the flow experience less deceleration and can even fly off out of the galaxy altogether,” said co-author Helen Russell, from the Institute of Astronomy at the University of Cambridge.

“If star formation is really occurring in most galactic outflows, as some theories predict, then this would provide a completely new scenario for our understanding of galaxy evolution,” added Maiolino.


Image credit: ESO/M. Kornmesser