From the University of Colorado Boulder: Researchers at the University of Colorado Boulder have completed an unprecedented "dissection" of twin galaxies in the final stages of the merger.
The new study, led by CU Boulder Research Associate Francisco Muller-Sánchez, explores a galaxy called NGC 6240. While most galaxies in the Universe have only one supermassive black hole at their center, NGC 6240 contains two – and they orbit each other in the last steps before they collide.  Research shows how gases ejected from these spiral black holes, in combination with gases ejected from stars in the galaxy, seem to block the production of new stars from NGC 6240. Müller-Sánchez & # 39; team also shows how these "winds" have helped create the galaxy's most intriguing feature: a massive gas cloud in the shape of a butterfly.
"We dissected the butterfly," said Müller-Sánchez of CU Boulder's Department of Astrophysical and Planetary Sciences (APS). "This is the first galaxy where we can simultaneously see the wind from the two supermassive black holes and the outflow of low ionization gas from star formation."
The team has partially tuned to NGC 6240 because galaxies with two supermassive black holes are relatively rare in their centers. Some experts also suspect that these twin hearts have caused the unusual appearance of the galaxy. Unlike the Milky Way, which forms a relatively clean disk, gas bubbles and gas jets of NGC 6240 discharge more than 30,000 light-years in space, resembling a butterfly in flight.
"Galaxies with a single supermassive black hole show such a phenomenal structure," said Müller-Sánchez.
In a study published in Nature on April 1
Those two winds cause the galaxy's gases to be evacuated by 100 times the Earth's mass of the Earth each year. This is a "very large number, comparable to the speed with which the galaxy generates stars in the core region," said Mueller-Sánchez.
Such an outflow can have a big impact on the galaxy itself. He explained that when two galaxies come together, they begin a feverish outburst of new star formation. Black hole and star winds, however, can slow down this process by clearing away the gases that make up fresh stars – much like a gust of wind can blow away the pile of leaves you just raked.
"NGC 6240 is in a unique phase of its evolution," said Julie Comerford, assistant professor at APS at CU Boulder and co-author of the new study. "It is now forming intense stars, so it needs the extra strong impact of two winds to slow down this star formation and evolve into a less active galaxy."
Other co-authors of the study are Rebecca Niven, a graduate student in APS at CU Boulder, Richard Davies at the Max Planck Institute for Extraterrestrial Physics in Germany, Ezequiel Treister at the Pontifical Catholic University of Chile and George Privon at the University of Florida
Photo credits: NGC 6240 as seen by the Hubble Space Telescope. Credit: NASA, ESA, Hubble Heritage (STScI / AURA) -ESA / Hubble Collaboration and A. Evans (University of Virginia, Charlottesville / NRAO / Stony Brook University)