Artist impression of an intermediate mass black hole
Credit: NASA

The Weight

Astronomers have a new method to weigh the mass of black holes. It involves determining the frequency of so-called quasi-periodic variations (QPOs). QPOs are nearly periodic variations in the X-ray brightness of the emission coming from the innermost regions of the disk of accreted material which swirls around the black hole before plunging out of existence. This new technique was invented by Nikolai Shaposhnikov and Lev Titarchuk at NASA's Goddard Space Flight Center (GSFC) and calibrated with observations of Cygnus X-1, a black hole whose mass is known since it's part of a binary system. Another group of GSFC scientists used this technique on a controversial object called NGC 5408 X-1. Using the XMM-Newton X-ray telescope, this group detected QPOs which they then used to determine the mass of the black hole in NGC 5408-X1, using the Shaposhnikov-Titarchuk technique. This new measure supports the idea that NGC 5408 X-1 is actually a member of the controversial class of intermediate mass black holes, similar to the one pictured in the artist's rendition above.

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Page Author: Dr. Michael F. Corcoran
Last modified Friday, 20-Apr-2012 15:20:51 EDT

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