ALMA Measures Mass of Black Hole with Extreme Precision

bystander · Post by **bystander** » Thu May 05, 2016 4:28 pm

ALMA Measures Mass of Black Hole with Extreme Precision
ALMA | NRAO | ESO | NAOJ | 2016 May 05

Combined image of NGC 1332 shows the central disk of gas surrounding the supermassive black hole at the center of the galaxy. New ALMA observations traced the motion of the disk, providing remarkably precise measurements of the black hole's mass: 660 million times the mass of our Sun. The red region in the ALMA image represents emission that has been redshifted by gas rotating away from us; the blue represents emission blue-shifted by gas rotating toward us. The range of colors represents rotational speeds up to 500 kilometers per second. (Credit: A. Barth (UCI), ALMA (NRAO/ESO/NAOJ); NASA/ESA Hubble; Carnegie-Irvine Galaxy Survey)
Supermassive black holes, some weighing millions to billions of times the mass of the Sun, dominate the centers of their host galaxies. To determine the actual mass of a supermassive black hole, astronomers must measure the strength of its gravitational pull on the stars and clouds of gas that swarm around it.

Using the Atacama Large Millimeter/submillimeter Array (ALMA), a team of astronomers has delved remarkably deep into the heart of a nearby elliptical galaxy to study the motion of a disk of cold interstellar gas encircling the supermassive black hole at its center. These observations provide one of the most accurate mass measurements to date for a black hole outside of our Galaxy, helping set the scale for these cosmic behemoths.

To obtain this result, Aaron Barth, ... and his team used ALMA to measure the speed of carbon monoxide gas in orbit around the black hole at the center of NGC 1332, a massive elliptical galaxy approximately 73 million light-years from Earth in the direction of the southern constellation Eridanus. ...

The ALMA observations reveal details of the disk's structure on the order of 16 light-years across. They also measure the disk's rotation well within the estimated 80 light-year radius of the black hole's "sphere of influence" – the region where the black hole's gravity is dominant. ...

Astronomers Determine Precise Mass of a Giant Black Hole
University of California, Irvine | 2016 May 05

Measurement of the Black Hole Mass in NGC 1332 from ALMA Observations at 0.044 Arcsecond Resolution - Aaron J. Barth et al

Astrophysical Journal Letters 822(2):L28 (10 May 2016) DOI: 10.3847/2041-8205/822/2/L28
arXiv.org > astro-ph > arXiv:1605.01346 > 04 May 2016