help

How Do You Measure the Mass of a Black Hole with Radio Waves?

-- | May 8, 2016

Question: How can you measure the mass of a black hole with radio waves? What is the mass of a typical black hole? — Ray

Answer: One can measure the mass of a black hole by tracing the motion of the gas and dust near the black hole that is being pulled-on by the mass of the black hole. This can be done at many wavelengths, such as by measuring the positions of stars which orbit near a black hole at optical wavelengths. At radio wavelengths, we can measure the emission from a specific type of emission from the water (H2O) molecule, which occurs at radio wavelengths, to trace the motions of the gas circling the black hole. Recently, the mass of a black hole in a nearby elliptical galaxy was measured by tracing the velocities of gas traced by the carbon monoxide (CO) molecule using the Atacama Large Millimeter Array (ALMA) telescope in Chile.

Jeff Mangum

Facebook
Pinterest
Twitter
Linkedin

The National Radio Astronomy Observatory is a facility of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
	Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.
	The U.S. National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."
	AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.