Astronomers spot black hole-powered ‘galactic fountain’

Astronomers have detected a vast “fountain” of cold molecular gas pumped into space by a central supermassive black hole that then rains back down on the galaxy in a cosmic deluge, fuelling repeated outflows. The fountain was found in the innermost 100,000 light years of the brightest galaxy in the Abell 2597 cluster. “This is possibly the first system in which we find clear evidence for both cold molecular gas inflow toward the black hole and outflow or uplift from the jets that the black hole launches,” said Grant Tremblay of the Harvard-Smithsonian Center for Astrophysics who led this study. “The supermassive black hole at the centre of this giant galaxy acts like a mechanical pump in a fountain.”

The team used the Atacama Large Millimetre Array, or ALMA, to track the motion of cold molecules within the nebula and the MUSE instrument on the European Southern Observatory’s Very Large Telescope to track the warmer material blasted away by the central black hole’s jets. “The unique aspect here is a very detailed coupled analysis of the source using data from ALMA and MUSE,” Tremblay explained. “The two facilities make for an incredibly powerful combination.”

A composite image of the Abell 2597 galaxy cluster shows warm gas (red) being pumped into space by a supermassive black hole with cooler gases (blue) raining back down on the originating galaxy. It is the first such “galactic fountain” observed with such visible outflows and subsequent outflows. Image: ALMA (ESO/NAOJ/NRAO), Tremblay et al.; NRAO/AUI/NSF, B. Saxton; NASA/Chandra; ESO/VLT