ALMA Weighs a Supermassive Black Hole 140 Million Times More Massive Than the Sun
Supermassive black holes can be found at the centers of every large galaxy. These massive objects can be millions to billions of times more massive than the sun. Now, ALMA has managed to "weigh" one of these supermassive black holes.
In this latest study, the researchers used ALMA to measure the mass of the supermassive black hole at the center of NGC 1097, a barred spiral galaxy located about 45 million light-years away in the direction of the constellation Fornax. The scientists determined that this galaxy harbors a black hole that's about 140 million times more massive than our sun. In comparison, the black hole at the center of the Milky Way has a mass that's just a few million times that of our sun.
But how did the researchers manage to measure this black hole? The scientists precisely measured the distribution and motion of two molecules-hydrogen cyanide (HCN) and formylium (HCO+)-near the central region of the galaxy. Then, they compared the ALMA observations to various mathematical models, each corresponding to a different mass of the supermassive black hole. The "best fit" for these observations corresponded to a black hole weighing in at about 140 million solar masses.
Previously, researchers used the CARMA telescope to measure the mass of the black hole at the center of the galaxy NGC 4526. This latest effort, though, had to employ different techniques.
"While NGC 4526 is a lenticular galaxy, NGC 1097 is a barred spiral galaxy," said Kyoko Onishi, one of the researchers, in a news release. "Recent observation results indicate the relationship between supermassive black hole mass and host galaxy properties varies depending on the type of galaxies, which makes it more important to derive accurate supermassive black hole masses in various types of galaxies."
The new measurement technique may shed light on the relationship between galaxies and their resident supermassive black holes.
The findings are published in The Astrophysical Journal.
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