ALMA and MUSE detect galactic fountain

A mere one billion light-years away in the nearby galaxy cluster known as Abell 2597, there lies a gargantuan galactic fountain. A massive black hole at the heart of a distant galaxy has been observed pumping a vast spout of cold molecular gas into space, which then rains back onto the black hole as an intergalactic deluge.

The in- and outflow of such a vast cosmic fountain has never before been observed in combination, and has its origin 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,” explained Grant Tremblay of the Harvard-Smithsonian Center for Astrophysics and former ESO Fellow, who led this study. “The supermassive black hole at the centre of this giant galaxy acts like a mechanical pump in a fountain.”

Tremblay and his team used ALMA to track the position and motion of molecules of carbon monoxide within the nebula. These cold molecules, with temperatures as low as minus 250-260°C, were found to be falling inwards to the black hole. The team also used data from the MUSE instrument on ESO's Very Large Telescope to track warmer gas — which is being launched out of the black hole in the form of 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.”

Together these two sets of data form a complete picture of the process; cold gas falls towards the black hole, igniting the black hole and causing it to launch fast-moving jets of incandescent plasma into the void. These jets then spout from the black hole in a spectacular galactic fountain. With no hope of escaping the galaxy's gravitational clutches, the plasma cools off, slows down, and eventually rains back down on the black hole, where the cycle begins anew.

This unprecedented observation could shed light on the life cycle of galaxies. The team speculates that this process may be not only common, but also essential to understanding galaxy formation. While the inflow and outflow of cold molecular gas have both previously been detected, this is the first time both have been detected within one system, and hence the first evidence that the two make up part of the same vast process.

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Abell 2597 is found in the constellation Aquarius, and is named for its inclusion in the Abell catalogue of rich clusters of galaxies. The catalogue also includes such clusters as the Fornax cluster, the Hercules cluster, and Pandora's cluster.

More information

This research was presented in a paper entitled “A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black Hole”, which appeared in The Astrophysical Journal.

The team was composed of G. R. Tremblay (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA; Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), F. Combes (LERMA, Observatoire de Paris, Sorbonne University, Paris, France), J. B. R. Oonk (ASTRON, Dwingeloo, the Netherlands; Leiden Observatory, the Netherlands), H. R. Russell (Institute of Astronomy, Cambridge University, UK), M. A. McDonald (Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, USA), M. Gaspari (Department of Astrophysical Sciences, Princeton University, USA), B. Husemann (Max-Planck-Institut für Astronomie, Heidelberg, Germany), P. E. J. Nulsen (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA; ICRAR, University of Western Australia, Crawley, Australia), B. R. McNamara (Physics & Astronomy Department, Waterloo University, Canada), S. L. Hamer (CRAL, Observatoire de Lyon, Université Lyon, France), C. P. O'Dea (Department of Physics & Astronomy, University of Manitoba, Winnipeg, Canada; School of Physics & Astronomy, Rochester Institute of Technology, USA), S. A. Baum (School of Physics & Astronomy, Rochester Institute of Technology, USA; Faculty of Science, University of Manitoba, Winnipeg, Canada), T. A. Davis (School of Physics & Astronomy, Cardiff University, UK), M. Donahue (Physics and Astronomy Department, Michigan State University, East Lansing, USA), G. M. Voit (Physics and Astronomy Department, Michigan State University, East Lansing, USA), A. C. Edge (Department of Physics, Durham University, UK), E. L. Blanton (Astronomy Department and Institute for Astrophysical Research, Boston University, USA), M. N. Bremer (H. W. Wills Physics Laboratory, University of Bristol, UK), E. Bulbul (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), T. E. Clarke (Naval Research Laboratory Remote Sensing Division, Washington, DC, USA), L. P. David (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), L. O. V. Edwards (Physics Department, California Polytechnic State University, San Luis Obispo, USA), D. Eggerman (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), A. C. Fabian (Institute of Astronomy, Cambridge University, UK), W. Forman (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), C. Jones (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), N. Kerman (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), R. P. Kraft (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), Y. Li (Center for Computational Astrophysics, Flatiron Institute, New York, USA; Department of Astronomy, University of Michigan, Ann Arbor, USA), M. Powell (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), S. W. Randall (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), P. Salomé (LERMA, Observatoire de Paris, Sorbonne University, Paris, France), A. Simionescu (Institute of Space and Astronautical Science [ISAS], Kanagawa, Japan), Y. Su (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), M. Sun (Department of Physics and Astronomy, University of Alabama in Huntsville, USA), C. M. Urry (Yale Center for Astronomy and Astrophysics, Yale University, New Haven, USA), A. N. Vantyghem (Physics & Astronomy Department, Waterloo University, Canada), B. J. Wilkes (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA) and J. A. ZuHone (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA).

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Links

• Research paper – http://iopscience.iop.org/article/10.3847/1538-4357/aad6dd
• Photos of ALMA – https://www.eso.org/public/images/archive/search/?adv=&subject_name=Atacama%20Large%20Millimeter/submillimeter%20Array
• Pictures of the VLT – https://www.eso.org/public/images/archive/search/?adv=&subject_name=Very%20Large%20Telescope

Contacts

Grant Tremblay
Harvard-Smithsonian Center for Astrophysics
Cambridge, USA
Tel: +1 207 504 4862
Email: grant.tremblay@cfa.harvard.edu

Francoise Combes
LERMA, Paris Observatory
Paris, France
Email: francoise.combes@obspm.fr

Calum Turner
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6670
Email: pio@eso.org

http://www.eso.org