Mordred said:
Thought this article may spark some interest if it works out we may gain a better understand of BH's.
http://www.sciencedaily.com/releases/2013/01/130130132324.htm
Here is an earlier article by some of the same authors that might be interesting as background to the one you mention:
http://arxiv.org/abs/1102.4877
Using the radio frequency emitted by carbon monoxide molecules to measure rotation---the swirling of gas cloud around a central mass---the doppler shift of the gas coming towards versus the gas going from. It's an interesting business. I hope we can sometime get an online link to the Nature article. I don't have one.
Timothy A. Davis, Martin Bureau, Michele Cappellari, Marc Sarzi, Leo Blitz. A black-hole mass measurement from molecular gas kinematics in NGC4526. Nature, 2013
Here's another link to comment on the article:
http://arstechnica.com/science/2013/01/better-black-hole-mass-estimates-in-hours/
Here's a link to supplementary material:
http://www.nature.com/nature/journal/vaop/ncurrent/extref/nature11819-s1.pdf
Here's the abstract of the article just published in Nature (but not the full article):
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11819.html
==quote==
A black-hole mass measurement from molecular gas kinematics in NGC4526
...
...
The masses of the supermassive black holes found in galaxy bulges are correlated with a multitude of galaxy properties1, 2, leading to suggestions that galaxies and black holes may evolve together3. The number of reliably measured black-hole masses is small, and the number of methods for measuring them is limited4, holding back attempts to understand this co-evolution. Directly measuring black-hole masses is currently possible with stellar kinematics (in early-type galaxies), ionized-gas kinematics (in some spiral and early-type galaxies5, 6, 7) and in rare objects that have central maser emission8. Here we report that by modelling the effect of a black hole on the kinematics of molecular gas it is possible to fit interferometric observations of CO emission and thereby accurately estimate black-hole masses. We study the dynamics of the gas in the early-type galaxy NGC 4526, and obtain a best fit that requires the presence of a central dark object of 4.5
+4.2-3.1 × 10
8 solar masses (3σ confidence limit). With the next-generation millimetre-wavelength interferometers these observations could be reproduced in galaxies out to 75 megaparsecs in less than 5 hours of observing time. The use of molecular gas as a kinematic tracer should thus allow one to estimate black-hole masses in hundreds of galaxies in the local Universe, many more than are accessible with current techniques.
==endquote==