Thanks to the ultra-precise measurements of the Atacama Large Millimeter/submillimeter Array (ALMA), a network of 66 radio telescopes in Chile, scientists have “weighed” a black hole roughly 660 million times greater than our own sun.
The supermassive black hole, found in Galaxy NGC 1332 located about 73 million light-years from Earth, is a bewildering one, with its staggering mass and a giant disc of cold gas circling it at around 1.1 million mph. The disc is usually invisible, but shines with carbon monoxide emissions when viewed with ALMA, allowing scientists to determine its orbit speed and mass.
The given calculation comes with a measurement uncertainty of about 10 percent — the most accurate measurement ever taken, thanks to ALMA’s array of over 60 antennas able to observe space in the millimeter and submillimeter wavelengths.
ALMA, in fact, is capable of determining the masses of supermassive black holes through “resolving gas kinematics on small angular scales in galaxy nuclei,” said study researcher and Rutgers professor Dr. Andrew J. Baker.
According to Baker, understanding how black holes — believed to swirl at the center of every galaxy, including the Milky Way — supermassive black holes form lends insight into how they profoundly influence the formation of the galaxies in which they live.
Black holes form with matter that turns so dense that not even light can escape gravity’s pull. During the infancy of the universe, gas was so aplenty that many black holes grew into supermassive sizes by swallowing it up, emitting intense energy amounts.
These supermassive black holes appear like mega-bright quasars if one looks back in time at the distant universe. Yet, as one looks closer to our planet, the sight is of galaxies with little gas (already converting into stars) and no quasars.
And they may be more common than previously thought.
A supermassive black hole, for instance, has been spotted in an old galaxy known as NGC 1600, with barely any new star formation and is situated in a “relative desert” in the universe. The galaxy is an unlikely home for the monstrous black hole, so the abundance of its kind offers the possibility of far more gigantic black holes than ever imagined.
Measuring the mass of these supermassive black holes is deemed the first step to solving the longstanding mystery about how they and their galaxies have come into being and co-evolved — and what forces shape our own solar system.
Previous black hole measurements were primarily taken using the Hubble Space Telescope, using observations of hotter disks of gas. Hotter gas spells more chaos and instability, increasing the uncertainty of the measurements. With ALMA's unprecedented precision, its observations play a critical role here.
“To reveal the relation between the SMBH and the host galaxy, we need to derive more SMBH masses in various types of galaxies,” said doctoral student Kyoko Onishi in a separate study using ALMA’s high sensitivity to measure a supermassive black hole in Galaxy 1097. “ALMA will enable us to observe a large number of galaxies in a practical length of time.”
