|J. B. Raymond Oonk
| On June 9th an international team of astronomers, including ASTRON astronomers Raymond Oonk and Michael Wise, reported witnessing a cosmic weather event in the form cold molecular gas clouds falling in towards the central supermassive black hole in the centrally dominant galaxy of the bright Abell 2597 galaxy cluster. This galaxy cluster is located at a distance of about 1 billion light-years from us.
These new ALMA (Atacama Large Millimeter/submillimeter Array) observations show for the first time unambiguous observational evidence for a chaotic, cold 'rain' feeding a supermassive black hole with a mass about 300 million times that of our Sun. The infalling clouds were revealed by narrow absorption features from carbon monoxide (CO) against the central line of sight towards the black hole.
The observed molecular cloud velocities, in combination with detailed very long baseline radio interferometric observations of cold atomic gas, place these clouds very the near (less than 300 lightyears) the black hole and on rapidly infalling orbits. Each of these clouds has a size of a few tens of light-years across and contains about a million solar masses of cold molecular gas. The discovered clouds are likely part of a much larger, centralized, clumpy distribution of cold clouds that provide the necessary fuel for the black hole regulating the thermal balance in the core of this galaxy cluster.
Image: The background image (blue) is from the NASA/ESA Hubble Space Telescope. The foreground (red) is ALMA data showing the distribution of carbon monoxide gas in and around the galaxy. The pull-out box shows the ALMA data of the "shadow" (black) produced by absorption of the millimetre-wavelength light emitted by electrons whizzing around powerful magnetic fields generated by the galaxy's supermassive black hole. The shadow indicates that cold clouds of molecular gas are raining in on the black hole. Credit: B. Saxton (NRAO/AUI/NSF)/G. Tremblay et al./NASA/ESA Hubble/ALMA (ESO/NAOJ/NRA)
The results have been published in Nature in a paper entitled "Cold, clumpy accretion onto an active supermassive black hole", by Grant R. Tremblay, J.B.R. Oonk et al. ( http://nature.com/articles/doi:10.1038/nature17969 ).
|Credit: B. Saxton (NRAO/AUI/NSF)/G. Tremblay et al./NASA/ESA Hubble/ALMA (ESO/NAOJ/NRA)