New method of measuring the mass of supermassive black holes
In a letter to Nature, an international team of astronomers, including Marc Sarzi from the University of Hertfordshire, report the exciting discovery of a new way to measure the mass of supermassive black holes in galaxies. By measuring the speed with which carbon monoxide molecules orbit around such black holes, this new research opens the possibility of making these measurements in many more galaxies than ever before.
A black hole is an object so dense that its gravity prevents anything, including light, from escaping. Supermassive black holes can be as much as a million to a billion times more massive than our Sun, and it is believed that most, if not all galaxies including the Milky Way,contain supermassive black holes at their centres - suggesting that the evolution of black holes and galaxies is very tightly linked.
Understanding the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies is one of the most active research areas in astrophysics.
Marc Sarzi, from the University of Hertfordshire’s Centre for Astrophysics Research, said: “There is an intriguing link between the mass of supermassive black holes and the mass of their host galaxies, but this is based only on quite a small number of estimates. Until now only three methods were used to measure the mass of supermassive black holes and these only work on relatively nearby galaxies. With this new technique, we have been able to show that we can measure black hole masses much further out in the universe, which will help understanding the role that supermassive black holes played during the formation of galaxies.”
Tim Davis, lead author of the paper and from the European Southern Observatory, commented: “We observed carbon monoxide molecules in the galaxy we were monitoring using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) telescope. With its super-sharp images we were able to zoom right into the centre of the galaxy and observe the gas whizzing around the black hole. This gas moves at a speed which is determined by the black-hole’s mass, and the distance from it. By measuring the velocity of the gas at each position, we can measure the mass of the black hole.”
The CARMA observations were rather challenging, but the new ALMA (Atacama Large Millimeter/submillimeter Array) telescope currently being built in Chile will allow this new technique to be applied more routinely to hundreds of galaxies in the nearby Universe.
ENDS
For more information, please contact Julie Cooper, University of Hertfordshire Press Office on 01707 284095, Email: j.cooper5@herts.ac.uk
Notes to Editor
Embargo: 18:00 GMT 30 January 2013
“A Black-hole mass measurement from molecular gas kinematics in NGC4526” is published in Nature on 31 January 2013.
For further information and image resources please visit: http://www.eso.org/~tdavis/BH_nature.php
Image caption: Image of Galaxy NGC4526 - the purple areas show the cold molecular gas which coincides with the dusty disk
About the Research Team
The international research team consists of:
Timothy A. Davis is based at the European Southern Observatory, and acknowledges funding support from the European Community's Seventh Framework Programme (/FP7/2007-2013/) under grant agreement No 229517.
Martin Bureau is based at University of Oxford and is supported by the rolling grants ‘Astrophysics at Oxford’ and from the UK Research Councils.
Michele Cappellari is based at University of Oxford and acknowledges support from a Royal Society University Research Fellowship.
Marc Sarzi is based at the Centre for Astrophysics Research at the University of Hertfordshire and acknowledges support from a Science and Technology Facilities Council (STFC) Advanced Fellowship.
Leo Blitz is based at the Department of Astronomy, University of California.
Support for CARMA construction was derived from the states of California, Illinois, and Maryland, the James S. McDonnell Foundation, the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the University of Chicago, the Associates of the California Institute of Technology, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement, and by the CARMA partner universities.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international partnership of Europe, North America and East Asia in cooperation with the Republic of Chile, is the largest astronomical project in existence. ALMA will be a single telescope of revolutionary design, composed initially of 66 high precision antennas located on the Chajnantor plateau, 5000 meters altitude in northern Chile.
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